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Fahrenthold BK, Cavanaugh MR, Tamhankar M, Lam BL, Feldon SE, Johnson BA, Huxlin KR. Training in Cortically Blinded Fields Appears to Confer Patient-Specific Benefit Against Retinal Thinning. Invest Ophthalmol Vis Sci 2024; 65:29. [PMID: 38635245 PMCID: PMC11033601 DOI: 10.1167/iovs.65.4.29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 03/06/2024] [Indexed: 04/19/2024] Open
Abstract
Purpose Damage to the adult primary visual cortex (V1) causes vision loss in the contralateral hemifield, initiating a process of transsynaptic retrograde degeneration (TRD). Here, we examined retinal correlates of TRD using a new metric to account for global changes in inner retinal thickness and asked if perceptual training in the intact or blind field impacts its progression. Methods We performed a meta-analysis of optical coherence tomography data in 48 participants with unilateral V1 stroke and homonymous visual defects who completed clinical trial NCT03350919. After measuring the thickness of the macular ganglion cell and inner plexiform layer (GCL-IPL) and the peripapillary retinal nerve fiber layer (RNFL), we computed individual laterality indices (LI) at baseline and after ∼6 months of daily motion discrimination training in the intact or blind field. Increasingly positive LI denoted greater layer thinning in retinal regions affected versus unaffected by the cortical damage. Results Pretraining, the affected GCL-IPL and RNFL were thinner than their unaffected counterparts, generating LI values positively correlated with time since stroke. Participants trained in their intact field exhibited increased LIGCL-IPL. Those trained in their blind field had no significant change in LIGCL-IPL. LIRNFL did not change in either group. Conclusions Relative shrinkage of the affected versus unaffected macular GCL-IPL can be reliably measured at an individual level and increases with time post-V1 stroke. Relative thinning progressed during intact-field training but appeared to be halted by training within the blind field, suggesting a potentially neuroprotective effect of this simple behavioral intervention.
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Affiliation(s)
- Berkeley K. Fahrenthold
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Matthew R. Cavanaugh
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Madhura Tamhankar
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Byron L. Lam
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, United States
| | - Steven E. Feldon
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Brent A. Johnson
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, New York, United States
| | - Krystel R. Huxlin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
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Yang (杨菁艺) J, Saionz EL, Cavanaugh MR, Fahrenthold BK, Melnick MD, Tadin D, Briggs F, Carrasco M, Huxlin KR. Limited restoration of contrast sensitivity with training after V1 damage in humans. eNeuro 2024; 11:ENEURO.0020-24.2024. [PMID: 38395611 PMCID: PMC10941636 DOI: 10.1523/eneuro.0020-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/15/2024] [Indexed: 02/25/2024] Open
Abstract
Stroke damage to the primary visual cortex (V1) causes severe visual deficits, which benefit from perceptual retraining. However, whereas training with high-contrast stimuli can locally restore orientation and motion direction discrimination abilities at trained locations, it only partially restores luminance contrast sensitivity (CS). Recent work revealed that high-contrast discrimination abilities may be preserved in the blind field of some patients early after stroke. Here, we asked if CS for orientation and direction discrimination is similarly preserved inside the blind field, to what extent, and whether it could benefit from a visual training intervention. Thirteen subacute patients (<3 months post-V1-stroke) and 12 chronic patients (>6 months post-V1-stroke) were pre-tested, then trained to discriminate either orientation or motion direction of Gabor patches of progressively lower contrasts as their performance improved. At baseline, more subacute than chronic participants could correctly discriminate the orientation of high-contrast Gabors in their blind field, but all failed to perform this task at lower contrasts, even when 10Hz flicker or motion direction were added. Training improved CS in a greater portion of subacute than chronic participants, but no-one attained normal CS, even when stimuli contained flicker or motion. We conclude that, unlike the near-complete training-induced restoration of high-contrast orientation and motion direction discrimination abilities, V1 damage in adulthood may severely limit the residual visual system's ability to regain normal CS. Our results support the notion that CS involves different neural substrates and computations than those required for orientation and direction discrimination in V1-damaged visual systems.Significance statement Stroke-induced V1 damage in adult humans induces a rapid and severe impairment of contrast sensitivity for orientation and motion direction discrimination in the affected hemifield, although discrimination of high-contrast stimuli can persist for several months. Adaptive training with Gabor patches of progressively lower contrasts improves contrast sensitivity for both orientation and motion discriminations in the blind-field of subacute (<3 months post-stroke) and chronic (>6 months post-stroke) participants; however, it fails to restore normal contrast sensitivity. Nonetheless, more subacute than chronic stroke participants benefit from such training, particularly when discriminating the orientation of static, non-flickering targets. Thus, contrast sensitivity appears critically dependent on processing within V1, with perceptual training displaying limited potential to fully restore it after V1 damage.
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Affiliation(s)
- Jingyi Yang (杨菁艺)
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Department of Neuroscience, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Elizabeth L. Saionz
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Matthew R. Cavanaugh
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Berkeley K. Fahrenthold
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Michael D. Melnick
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, New York 14627
| | - Duje Tadin
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, New York 14627
| | - Farran Briggs
- Department of Neuroscience, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, New York 14627
| | - Marisa Carrasco
- Department of Psychology and Center for Neural Science, New York University, New York, New York 10003
| | - Krystel R. Huxlin
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Department of Neuroscience, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, New York 14627
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Fahrenthold BK, Cavanaugh MR, Tamhankar M, Lam BL, Feldon SE, Johnson BA, Huxlin KR. Training in cortically-blind fields confers patient-specific benefit against retinal thinning after occipital stroke. medRxiv 2023:2023.12.19.23298260. [PMID: 38196617 PMCID: PMC10775322 DOI: 10.1101/2023.12.19.23298260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
Purpose Damage to the adult primary visual cortex (V1) causes vision loss in the contralateral hemifield, initiating a process of trans-synaptic retrograde degeneration (TRD). Here, we examined retinal correlates of TRD using a new metric to account for global changes in inner retinal thickness, and asked if perceptual training in the intact or blind field impacts its progression. Methods We performed a meta-analysis of optical coherence tomography (OCT) data in 48 participants with unilateral V1 stroke and homonymous visual defects, who completed clinical trial NCT03350919. After measuring the thickness of the macular ganglion cell and inner plexiform layers (GCL-IPL), and the peripapillary retinal nerve fiber layer (RNFL), we computed individual laterality indices (LI) at baseline and after ~6 months of daily motion discrimination training in the intact- or blind-field. Increasingly positive LI denoted greater layer thinning in retinal regions affected versus unaffected by the cortical damage. Results Pre-training, the affected GCL-IPL and RNFL were thinner than their unaffected counterparts, generating LI values positively correlated with time since stroke. Participants trained in their intact-field exhibited increased LIGCL-IPL. Those trained in their blind-field had no significant change in LIGCL-IPL. LIRNFL did not change in either group. Conclusions Relative shrinkage of the affected versus unaffected macular GCL-IPL can be reliably measured at an individual level and increases with time post-V1 stroke. Relative thinning progressed during intact-field training, but appeared to be halted by training within the blind field, suggesting a potentially neuroprotective effect of this simple behavioral intervention.
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Affiliation(s)
- Berkeley K. Fahrenthold
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Matthew R. Cavanaugh
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Madhura Tamhankar
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Byron L. Lam
- Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
| | - Steven E. Feldon
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Brent A. Johnson
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, USA
| | - Krystel R. Huxlin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, USA
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Jeon KI, Kumar A, Callan CL, DeMagistris M, MacRae S, Nehrke K, Huxlin KR. Blocking Mitochondrial Pyruvate Transport Alters Corneal Myofibroblast Phenotype: A New Target for Treating Fibrosis. Invest Ophthalmol Vis Sci 2023; 64:36. [PMID: 37870848 PMCID: PMC10599161 DOI: 10.1167/iovs.64.13.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/21/2023] [Indexed: 10/24/2023] Open
Abstract
Purpose The purpose of this study was to critically test the hypothesis that mitochondrial pyruvate carrier (MPC) function is essential for maintenance of the corneal myofibroblast phenotype in vitro and in vivo. Methods Protein and mRNA for canonical profibrotic markers were assessed in cultured cat corneal myofibroblasts generated via transforming growth factor (TGF)-β1 stimulation and treated with either the thiazolidinedione (TZD) troglitazone or the MPC inhibitor alpha-cyano-beta-(1-phenylindol-3-yl) acrylate (UK-5099). RNA sequencing was used to gain insight into signaling modules related to instructive, permissive, or corollary changes in gene expression following treatment. A feline photorefractive keratectomy (PRK) model of corneal wounding was used to test the efficacy of topical troglitazone at reducing α-smooth muscle actin (SMA)-positive staining when applied 2 to 4 weeks postoperatively, during peak fibrosis. Results Troglitazone caused cultured myofibroblasts to adopt a fibroblast-like phenotype through a noncanonical, peroxisome proliferator-activated receptor (PPAR)-γ-independent mechanism. Direct MPC inhibition using UK-5099 recapitulated this effect, but classic inhibitors of oxidative phosphorylation (OXPHOS) did not. Gene Set Enrichment Analysis (GSEA) of RNA sequencing data converged on energy substrate utilization and the Mitochondrial Permeability Transition pore as key players in myofibroblast maintenance. Finally, troglitazone applied onto an established zone of active fibrosis post-PRK significantly reduced stromal α-SMA expression. Conclusions Our results provide empirical evidence that metabolic remodeling in myofibroblasts creates selective vulnerabilities beyond simply mitochondrial energy production, and that these are critical for maintenance of the myofibroblast phenotype. For the first time, we provide proof-of-concept data showing that this remodeling can be exploited to treat existing corneal fibrosis via inhibition of the MPC.
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Affiliation(s)
- Kye-Im Jeon
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Ankita Kumar
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Christine L Callan
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Margaret DeMagistris
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Scott MacRae
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Keith Nehrke
- Department of Medicine-Nephrology Division, University of Rochester, Rochester, New York, United States
| | - Krystel R Huxlin
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, United States
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Yang J, Saionz EL, Cavanaugh MR, Fahrenthold BK, Melnick MD, Tadin D, Briggs F, Carrasco M, Huxlin KR. Contrast sensitivity: a fundamental limit to vision restoration after V1 damage. medRxiv 2023:2023.08.31.23294827. [PMID: 37693553 PMCID: PMC10491352 DOI: 10.1101/2023.08.31.23294827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Stroke damage to the primary visual cortex (V1) causes severe visual deficits, which benefit from perceptual retraining. However, whereas training with high-contrast stimuli can locally restore orientation and direction discrimination abilities at trained locations, it only partially restores luminance contrast sensitivity (CS). Recent work revealed that high-contrast discrimination abilities may be preserved in the blind field of some patients early after stroke. Here, we asked if CS for orientation and direction discrimination is similarly preserved inside the blind field, to what extent, and whether it could benefit from a visual training intervention. Thirteen subacute (<3 months post-V1-stroke) and 12 chronic (>6 months post-V1-stroke) participants were pre-tested, then trained to discriminate either orientation or motion direction of Gabor patches of progressively lower contrasts. At baseline, more subacute than chronic participants could correctly discriminate the orientation of high-contrast Gabors in their blind field, but all failed to perform this task at lower contrasts, even when 10Hz flicker or motion direction were added. Training improved CS in a greater portion of subacute than chronic participants, but no-one attained normal CS, even when stimuli contained flicker or motion. We conclude that, unlike the near-complete training-induced restoration of high-contrast orientation and direction discrimination, there is limited capacity for restoring CS after V1 damage in adulthood. Our results suggest that CS involves different neural substrates and computations than those required for orientation and direction discrimination in V1-damaged visual systems.
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Affiliation(s)
- Jingyi Yang
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Department of Neuroscience, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Elizabeth L. Saionz
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Matthew R. Cavanaugh
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Berkeley K. Fahrenthold
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Michael D. Melnick
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, New York 14627
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Duje Tadin
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, New York 14627
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Farran Briggs
- Department of Neuroscience, University of Rochester Medical Center, Rochester, New York 14642
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, New York 14627
- Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Marisa Carrasco
- Department of Psychology and Center for Neural Science, New York University, NY, NY 10003
| | - Krystel R. Huxlin
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York 14642
- Department of Neuroscience, University of Rochester Medical Center, Rochester, New York 14642
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, New York 14627
- Center for Visual Science, University of Rochester, Rochester, New York 14627
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Willis HE, Ip IB, Watt A, Campbell J, Jbabdi S, Clarke WT, Cavanaugh MR, Huxlin KR, Watkins KE, Tamietto M, Bridge H. GABA and Glutamate in hMT+ Link to Individual Differences in Residual Visual Function After Occipital Stroke. Stroke 2023; 54:2286-2295. [PMID: 37477008 PMCID: PMC10453332 DOI: 10.1161/strokeaha.123.043269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 05/09/2023] [Accepted: 05/31/2023] [Indexed: 07/22/2023]
Abstract
BACKGROUND Damage to the primary visual cortex following an occipital stroke causes loss of conscious vision in the contralateral hemifield. Yet, some patients retain the ability to detect moving visual stimuli within their blind field. The present study asked whether such individual differences in blind field perception following loss of primary visual cortex could be explained by the concentration of neurotransmitters γ-aminobutyric acid (GABA) and glutamate or activity of the visual motion processing, human middle temporal complex (hMT+). METHODS We used magnetic resonance imaging in 19 patients with chronic occipital stroke to measure the concentration of neurotransmitters GABA and glutamate (proton magnetic resonance spectroscopy) and functional activity in hMT+ (functional magnetic resonance imaging). We also tested each participant on a 2-interval forced choice detection task using high-contrast, moving Gabor patches. We then measured and assessed the strength of relationships between participants' residual vision in their blind field and in vivo neurotransmitter concentrations, as well as visually evoked functional magnetic resonance imaging activity in their hMT+. Levels of GABA and glutamate were also measured in a sensorimotor region, which served as a control. RESULTS Magnetic resonance spectroscopy-derived GABA and glutamate concentrations in hMT+ (but not sensorimotor cortex) strongly predicted blind-field visual detection abilities. Performance was inversely related to levels of both inhibitory and excitatory neurotransmitters in hMT+ but, surprisingly, did not correlate with visually evoked blood oxygenation level-dependent signal change in this motion-sensitive region. CONCLUSIONS Levels of GABA and glutamate in hMT+ appear to provide superior information about motion detection capabilities inside perimetrically defined blind fields compared to blood oxygenation level-dependent signal changes-in essence, serving as biomarkers for the quality of residual visual processing in the blind-field. Whether they also reflect a potential for successful rehabilitation of visual function remains to be determined.
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Affiliation(s)
- Hanna E. Willis
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences (H.E.W., I.B.I., A.W., J.C., S.J., W.T.C., H.B.), University of Oxford, United Kingdom
| | - I. Betina Ip
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences (H.E.W., I.B.I., A.W., J.C., S.J., W.T.C., H.B.), University of Oxford, United Kingdom
| | - Archie Watt
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences (H.E.W., I.B.I., A.W., J.C., S.J., W.T.C., H.B.), University of Oxford, United Kingdom
| | - Jon Campbell
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences (H.E.W., I.B.I., A.W., J.C., S.J., W.T.C., H.B.), University of Oxford, United Kingdom
| | - Saad Jbabdi
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences (H.E.W., I.B.I., A.W., J.C., S.J., W.T.C., H.B.), University of Oxford, United Kingdom
| | - William T. Clarke
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences (H.E.W., I.B.I., A.W., J.C., S.J., W.T.C., H.B.), University of Oxford, United Kingdom
| | - Matthew R. Cavanaugh
- Flaum Eye Institute and Center for Visual Science, University of Rochester, NY (M.R.C., K.R.H.)
| | - Krystel R. Huxlin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, NY (M.R.C., K.R.H.)
| | - Kate E. Watkins
- Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology (K.E.W.), University of Oxford, United Kingdom
| | - Marco Tamietto
- Department of Psychology, University of Torino, Italy (M.T.)
- Department of Medical and Clinical Psychology, and CoRPS—Center of Research on Psychology in Somatic Diseases—Tilburg University, the Netherlands (M.T.)
| | - Holly Bridge
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences (H.E.W., I.B.I., A.W., J.C., S.J., W.T.C., H.B.), University of Oxford, United Kingdom
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Bevilacqua M, Huxlin KR, Hummel FC, Raffin E. Pathway and directional specificity of Hebbian plasticity in the cortical visual motion processing network. iScience 2023; 26:107064. [PMID: 37408682 PMCID: PMC10319215 DOI: 10.1016/j.isci.2023.107064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 02/14/2023] [Accepted: 06/02/2023] [Indexed: 07/07/2023] Open
Abstract
Cortico-cortical paired associative stimulation (ccPAS), which repeatedly pairs single-pulse transcranial magnetic stimulation (TMS) over two distant brain regions, is thought to modulate synaptic plasticity. We explored its spatial selectivity (pathway and direction specificity) and its nature (oscillatory signature and perceptual consequences) when applied along the ascending (Forward) and descending (Backward) motion discrimination pathway. We found unspecific connectivity increases in bottom-up inputs in the low gamma band, probably reflecting visual task exposure. A clear distinction in information transfer occurred in the re-entrant alpha signals, which were only modulated by Backward-ccPAS, and predictive of visual improvements in healthy participants. These results suggest a causal involvement of the re-entrant MT-to-V1 low-frequency inputs in motion discrimination and integration in healthy participants. Modulating re-entrant input activity could provide single-subject prediction scenarios for visual recovery. Visual recovery might indeed partly rely on these residual inputs projecting to spared V1 neurons.
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Affiliation(s)
- Michele Bevilacqua
- Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, EPFL, Geneva, Switzerland
- Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland
| | - Krystel R. Huxlin
- The Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Friedhelm C. Hummel
- Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, EPFL, Geneva, Switzerland
- Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland
- Clinical Neuroscience, University of Geneva Medical School, Geneva, Switzerland
| | - Estelle Raffin
- Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, EPFL, Geneva, Switzerland
- Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland
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Bevilacqua M, Zandvliet S, Menoud P, Windel F, Huxlin KR, Hummel FC, Raffin E. Cortico-cortical Paired Associative Stimulation can probe visual integrity in patients with visual field loss. Brain Stimul 2023. [DOI: 10.1016/j.brs.2023.01.705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
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Yang J, Saionz EL, Melnick MD, Fahrenthold BK, Cavanaugh MR, Briggs F, Tadin D, Huxlin KR. Relative efficacy of training with low-contrast Gabors in subacute versus chronic cortically-induced blindness. J Vis 2022. [DOI: 10.1167/jov.22.14.3444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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10
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Willis HE, Ip IB, Watt A, Jbabdi S, Clarke W, Cavanaugh MR, Huxlin KR, Watkins KE, Tamietto M, Bridge H. Neurochemistry in hMT+ underlies residual vision in visual loss after stroke. J Vis 2022. [DOI: 10.1167/jov.22.14.3990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Hanna E. Willis
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom, OX3 9DU
| | - I. Betina Ip
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom, OX3 9DU
| | - Archie Watt
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom, OX3 9DU
| | - Saad Jbabdi
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom, OX3 9DU
| | - William Clarke
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom, OX3 9DU
| | - Matthew R. Cavanaugh
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY 14642, USA
| | - Krystel R. Huxlin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY 14642, USA
| | - Kate E. Watkins
- Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom, OX2 6GG
| | - Marco Tamietto
- Department of Psychology, University of Torino, 10123 Torino, Italy
| | - Holly Bridge
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom, OX3 9DU
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Raffin E, Salamanca-Giron RF, Huxlin KR, Reynaud O, Mattera L, Martuzzi R, Hummel FC. TU-122. Adaptive brain changes to TMS Over V1 and V5 determined by concurrent TMS-fMRI. Clin Neurophysiol 2022. [DOI: 10.1016/j.clinph.2022.07.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kwon S, Fahrenthold BK, Cavanaugh MR, Huxlin KR, Mitchell JF. Perceptual restoration fails to recover unconscious processing for smooth eye movements after occipital stroke. eLife 2022; 11:67573. [PMID: 35730931 PMCID: PMC9255960 DOI: 10.7554/elife.67573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 06/21/2022] [Indexed: 11/28/2022] Open
Abstract
The visual pathways that guide actions do not necessarily mediate conscious perception. Patients with primary visual cortex (V1) damage lose conscious perception but often retain unconscious abilities (e.g. blindsight). Here, we asked if saccade accuracy and post-saccadic following responses (PFRs) that automatically track target motion upon saccade landing are retained when conscious perception is lost. We contrasted these behaviors in the blind and intact fields of 11 chronic V1-stroke patients, and in 8 visually intact controls. Saccade accuracy was relatively normal in all cases. Stroke patients also had normal PFR in their intact fields, but no PFR in their blind fields. Thus, V1 damage did not spare the unconscious visual processing necessary for automatic, post-saccadic smooth eye movements. Importantly, visual training that recovered motion perception in the blind field did not restore the PFR, suggesting a clear dissociation between pathways mediating perceptual restoration and automatic actions in the V1-damaged visual system.
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Affiliation(s)
- Sunwoo Kwon
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, United States
| | | | - Matthew R Cavanaugh
- Center for Visual Science, University of Rochester, Rochester, United States
| | - Krystel R Huxlin
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, United States
| | - Jude F Mitchell
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, United States
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13
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Cavanaugh MR, Tadin D, Carrasco M, Huxlin KR. Benefits of Endogenous Spatial Attention During Visual Double-Training in Cortically-Blinded Fields. Front Neurosci 2022; 16:771623. [PMID: 35495043 PMCID: PMC9046589 DOI: 10.3389/fnins.2022.771623] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 03/08/2022] [Indexed: 12/12/2022] Open
Abstract
Recovery of visual discrimination thresholds inside cortically-blinded (CB) fields is most commonly attained at a single, trained location at a time, with iterative progress deeper into the blind field as performance improves over several months. As such, training is slow, inefficient, burdensome, and often frustrating for patients. Here, we investigated whether double-location training, coupled with a covert spatial-attention (SA) pre-cue, could improve the efficiency of training. Nine CB participants completed a randomized, training assignment with either a spatial attention or neutral pre-cue. All trained for a similar length of time on a fine direction discrimination task at two blind field locations simultaneously. Training stimuli and tasks for both cohorts were identical, save for the presence of a central pre-cue, to manipulate endogenous (voluntary) SA, or a Neutral pre-cue. Participants in the SA training cohort demonstrated marked improvements in direction discrimination thresholds, albeit not to normal/intact-field levels; participants in the Neutral training cohort remained impaired. Thus, double-training within cortically blind fields, when coupled with SA pre-cues can significantly improve direction discrimination thresholds at two locations simultaneously, offering a new method to improve performance and reduce the training burden for CB patients. Double-training without SA pre-cues revealed a hitherto unrecognized limitation of cortically-blind visual systems’ ability to improve while processing two stimuli simultaneously. These data could potentially explain why exposure to the typically complex visual environments encountered in everyday life is insufficient to induce visual recovery in CB patients. It is hoped that these new insights will direct both research and therapeutic developments toward methods that can attain better, faster recovery of vision in CB fields.
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Affiliation(s)
- Matthew R. Cavanaugh
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, United States
| | - Duje Tadin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, United States
- Department of Brain and Cognitive Sciences and Center for Visual Science, University of Rochester, Rochester, NY, United States
| | - Marisa Carrasco
- Department of Psychology and Center for Neural Science, New York University, New York, NY, United States
| | - Krystel R. Huxlin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, United States
- Department of Brain and Cognitive Sciences and Center for Visual Science, University of Rochester, Rochester, NY, United States
- *Correspondence: Krystel R. Huxlin,
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14
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Huang R, Yu D, Savage D, Wozniak K, Zheleznyak L, Knox WH, Huxlin KR. Blue-LIRIC in the rabbit cornea: efficacy, tissue effects, and repetition rate scaling. Biomed Opt Express 2022; 13:2346-2363. [PMID: 35519279 PMCID: PMC9045900 DOI: 10.1364/boe.448286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/20/2022] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Laser-induced refractive index change (LIRIC) is being developed as a non-invasive way to alter optical properties of transparent, ophthalmic materials including corneas ex vivo and in vivo. This study examined the optical and biological effects of blue-LIRIC (wavelengths 400-405 nm) of ex-vivo rabbit corneas. Following LIRIC treatment at low and high repetition rates (8.3 MHz and 80 MHz, respectively), we interferometrically measured optical phase change, obtained transmission electron microscopy (TEM) micrographs, and stained histological sections with collagen hybridizing peptides (CHP) to assess the structural and organizational changes caused by LIRIC at different repetition rates. Finally, we performed power and scan speed scaling experiments at three different repetition rates (1 MHz, 8.3 MHz, and 80 MHz) to study their impact on LIRIC efficacy. Histologic co-localization of CHP and LIRIC-generated green autofluorescence signals suggested that collagen denaturation had occurred in the laser-irradiated region. TEM imaging showed different ultrastructural modifications for low and high repetition rate writing, with discrete homogenization of collagen fibrils at 80 MHz, as opposed to contiguous homogenization at 8.3 MHz. Overall, this study confirmed that LIRIC efficacy can be dramatically increased, while still avoiding tissue ablation, by lowering the repetition rate from 80 MHz to 8.3 MHz. Modeling suggests that this is due to a higher, single-pulse, energy density deposition at given laser powers during 8.3 MHz LIRIC.
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Affiliation(s)
- Ruiting Huang
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Dan Yu
- Materials Science Program, University of Rochester, Rochester, NY 14627, USA
| | - Daniel Savage
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | - Kaitlin Wozniak
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | | | - Wayne H. Knox
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Materials Science Program, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Krystel R. Huxlin
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
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15
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Jeon KI, Kumar A, Wozniak KT, Nehrke K, Huxlin KR. Defining the Role of Mitochondrial Fission in Corneal Myofibroblast Differentiation. Invest Ophthalmol Vis Sci 2022; 63:2. [PMID: 35377925 PMCID: PMC8994166 DOI: 10.1167/iovs.63.4.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Fibrosis caused by corneal wounding can lead to scar formation, impairing vision. Although preventing fibroblast-to-myofibroblast differentiation has therapeutic potential, effective mechanisms for doing so remain elusive. Recent work shows that mitochondria contribute to differentiation in several tissues. Here, we tested the hypothesis that mitochondrial dynamics, and specifically fission, are key for transforming growth factor (TGF)-β1-induced corneal myofibroblast differentiation. Methods Mitochondrial fission was inhibited pharmacologically in cultured primary cat corneal fibroblasts. We measured its impact on molecular markers of myofibroblast differentiation and assessed changes in mitochondrial morphology through fluorescence imaging. The phosphorylation status of established regulatory proteins, both of myofibroblast differentiation and mitochondrial fission, was assessed by Western analysis. Results Pharmacological inhibition of mitochondrial fission suppressed TGF-β1-induced increases in alpha-smooth muscle actin, collagen 1, and fibronectin expression, and prevented phosphorylation of c-Jun N-terminal kinase (JNK), but not small mothers against decapentaplegic 3, p38 mitogen-activated protein kinase (p38), extracellular signal-regulated kinase 1 (ERK1), or protein kinase B (AKT). TGF-β1 increased phosphorylation of dynamin-related protein 1 (DRP1), a mitochondrial fission regulator, and caused fragmentation of the mitochondrial network. Although inhibition of JNK, ERK1, or AKT prevented phosphorylation of DRP1, none sufficed to independently suppress TGF-β1-induced fragmentation. Conclusions Mitochondrial dynamics play a key role in early corneal fibrogenesis, acting together with profibrotic signaling. This is consistent with mitochondria's role as signaling hubs that coordinate metabolic decision-making. This suggests a feed-forward cascade through which mitochondria, at least in part through fission, reinforce noncanonical TGF-β1 signaling to attain corneal myofibroblast differentiation.
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Affiliation(s)
- Kye-Im Jeon
- Department of Ophthalmology, University of Rochester, Rochester, New York, United States.,Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Ankita Kumar
- Department of Ophthalmology, University of Rochester, Rochester, New York, United States
| | - Kaitlin T Wozniak
- Department of Ophthalmology, University of Rochester, Rochester, New York, United States.,Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Keith Nehrke
- Department of Medicine - Nephrology Division, University of Rochester, Rochester, New York, United States
| | - Krystel R Huxlin
- Department of Ophthalmology, University of Rochester, Rochester, New York, United States.,Center for Visual Science, University of Rochester, Rochester, New York, United States
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16
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Raffin E, Witon A, Salamanca-Giron RF, Huxlin KR, Hummel FC. Functional Segregation within the Dorsal Frontoparietal Network: A Multimodal Dynamic Causal Modeling Study. Cereb Cortex 2021; 32:3187-3205. [PMID: 34864941 DOI: 10.1093/cercor/bhab409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 10/12/2021] [Accepted: 10/15/2021] [Indexed: 12/27/2022] Open
Abstract
Discrimination and integration of motion direction requires the interplay of multiple brain areas. Theoretical accounts of perception suggest that stimulus-related (i.e., exogenous) and decision-related (i.e., endogenous) factors affect distributed neuronal processing at different levels of the visual hierarchy. To test these predictions, we measured brain activity of healthy participants during a motion discrimination task, using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). We independently modeled the impact of exogenous factors (task demand) and endogenous factors (perceptual decision-making) on the activity of the motion discrimination network and applied Dynamic Causal Modeling (DCM) to both modalities. DCM for event-related potentials (DCM-ERP) revealed that task demand impacted the reciprocal connections between the primary visual cortex (V1) and medial temporal areas (V5). With practice, higher visual areas were increasingly involved, as revealed by DCM-fMRI. Perceptual decision-making modulated higher levels (e.g., V5-to-Frontal Eye Fields, FEF), in a manner predictive of performance. Our data suggest that lower levels of the visual network support early, feature-based selection of responses, especially when learning strategies have not been implemented. In contrast, perceptual decision-making operates at higher levels of the visual hierarchy by integrating sensory information with the internal state of the subject.
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Affiliation(s)
- Estelle Raffin
- Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, EPFL, Geneva CH-1201, Switzerland.,Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion CH-1950, Switzerland
| | - Adrien Witon
- Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, EPFL, Geneva CH-1201, Switzerland.,Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion CH-1950, Switzerland.,Health IT, IT Department, Hôpital du Valais, Sion, Switzerland
| | - Roberto F Salamanca-Giron
- Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, EPFL, Geneva CH-1201, Switzerland.,Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion CH-1950, Switzerland
| | - Krystel R Huxlin
- The Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY-14642, USA
| | - Friedhelm C Hummel
- Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, EPFL, Geneva CH-1201, Switzerland.,Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion CH-1950, Switzerland.,Clinical Neuroscience, University of Geneva Medical School, Geneva CH-1205, Switzerland
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17
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Abstract
Supplemental Digital Content is available in the text. Background and Purpose: Damage to the adult primary visual cortex (V1) causes vision loss in the contralateral visual hemifield, initiating a process of trans-synaptic retrograde degeneration. The present study examined functional implications of this process, asking if degeneration impacted the amount of visual recovery attainable from visual restoration training in chronic patients, and if restoration training impacted optic tract (OT) shrinkage. Methods: Magnetic resonance imaging was used to measure OT volumes bilaterally in 36 patients with unilateral occipital stroke. From OT volumes, we computed laterality indices (LI), estimating the stroke-induced OT shrinkage in each case. A subset of these chronic patients (n=14, 13±6 months poststroke) underwent an average of nearly 1 year of daily visual restoration training, which repeatedly stimulated vision in their blind field. The amount of visual field recovery was quantified using Humphrey perimetry, and post training magnetic resonance imaging was used to assess the impact of training on OT shrinkage. Results: OT LI was correlated with time since stroke: it was close to 0 (no measurable OT shrinkage) in subacute participants (<6 months poststroke) while chronic participants (>6 months poststroke) exhibited LI >0, but with significant variability. Visual training did not systematically alter LI, but chronic patients with baseline LI≈0 (no OT shrinkage) exhibited greater visual field recovery than those with LI>0. Conclusions: Unilateral OT shrinkage becomes detectable with magnetic resonance imaging by ≈7 months poststroke, albeit with significant interindividual variability. Although visual restoration training did not alter the amount of degeneration already sustained, OT shrinkage appeared to serve as a biomarker of the potential for training-induced visual recovery in chronic cortically blind patients.
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Affiliation(s)
- Berkeley K. Fahrenthold
- Flaum Eye Institute (B.K.F., M.R.C., S.J., K.R.H.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | - Matthew R. Cavanaugh
- Flaum Eye Institute (B.K.F., M.R.C., S.J., K.R.H.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | - Subin Jang
- Flaum Eye Institute (B.K.F., M.R.C., S.J., K.R.H.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | - Allison J. Murphy
- Neuroscience Graduate Program (A.J.M.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | | | | | - Krystel R. Huxlin
- Flaum Eye Institute (B.K.F., M.R.C., S.J., K.R.H.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
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18
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Salamanca-Giron RF, Raffin E, Zandvliet SB, Seeber M, Michel CM, Sauseng P, Huxlin KR, Hummel FC. Enhancing visual motion discrimination by desynchronizing bifocal oscillatory activity. Neuroimage 2021; 240:118299. [PMID: 34171500 DOI: 10.1016/j.neuroimage.2021.118299] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 06/11/2021] [Accepted: 06/20/2021] [Indexed: 11/17/2022] Open
Abstract
Visual motion discrimination involves reciprocal interactions in the alpha band between the primary visual cortex (V1) and mediotemporal areas (V5/MT). We investigated whether modulating alpha phase synchronization using individualized multisite transcranial alternating current stimulation (tACS) over V5 and V1 regions would improve motion discrimination. We tested 3 groups of healthy subjects with the following conditions: (1) individualized In-Phase V1alpha-V5alpha tACS (0° lag), (2) individualized Anti-Phase V1alpha-V5alpha tACS (180° lag) and (3) sham tACS. Motion discrimination and EEG activity were recorded before, during and after tACS. Performance significantly improved in the Anti-Phase group compared to the In-Phase group 10 and 30 min after stimulation. This result was explained by decreases in bottom-up alpha-V1 gamma-V5 phase-amplitude coupling. One possible explanation of these results is that Anti-Phase V1alpha-V5alpha tACS might impose an optimal phase lag between stimulation sites due to the inherent speed of wave propagation, hereby supporting optimized neuronal communication.
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Affiliation(s)
- Roberto F Salamanca-Giron
- Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), Campus Biotech, Room H4.3.132.084, Chemin des Mines 9, Geneva, Switzerland; Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland
| | - Estelle Raffin
- Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), Campus Biotech, Room H4.3.132.084, Chemin des Mines 9, Geneva, Switzerland; Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland
| | - Sarah B Zandvliet
- Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), Campus Biotech, Room H4.3.132.084, Chemin des Mines 9, Geneva, Switzerland; Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland
| | - Martin Seeber
- Functional Brain Mapping Lab, Department of Fundamental Neurosciences, University of Geneva, Campus Biotech, Chemin des Mines 9, 1202, Geneva, Switzerland
| | - Christoph M Michel
- Functional Brain Mapping Lab, Department of Fundamental Neurosciences, University of Geneva, Campus Biotech, Chemin des Mines 9, 1202, Geneva, Switzerland; Lemanic Biomedical Imaging Centre (CIBM), Lausanne, Geneva, Switzerland
| | - Paul Sauseng
- Department of Psychology, LMU Munich, Leopoldstr. 13, Munich 80802, Germany
| | - Krystel R Huxlin
- The Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Friedhelm C Hummel
- Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), Campus Biotech, Room H4.3.132.084, Chemin des Mines 9, Geneva, Switzerland; Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland; Clinical Neuroscience, University of Geneva Medical School, Geneva, Switzerland.
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19
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Hagan MA, Chaplin TA, Huxlin KR, Rosa MGP, Lui LL. Altered Sensitivity to Motion of Area MT Neurons Following Long-Term V1 Lesions. Cereb Cortex 2021; 30:451-464. [PMID: 31211357 DOI: 10.1093/cercor/bhz096] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 04/16/2019] [Accepted: 04/16/2019] [Indexed: 02/04/2023] Open
Abstract
Primates with primary visual cortex (V1) damage often retain residual motion sensitivity, which is hypothesized to be mediated by middle temporal area (MT). MT neurons continue to respond to stimuli shortly after V1 lesions; however, experimental and clinical studies of lesion-induced plasticity have shown that lesion effects can take several months to stabilize. It is unknown what physiological changes occur in MT and whether neural responses persist long after V1 damage. We recorded neuronal responses in MT to moving dot patterns in adult marmoset monkeys 6-12 months after unilateral V1 lesions. In contrast to results obtained shortly after V1 lesions, we found that fewer MT neurons were direction selective, including neurons expected to still receive projections from remaining parts of V1. The firing rates of most cells increased with increases in motion strength, regardless of stimulus direction. Furthermore, firing rates were higher and more variable than in control MT cells. To test whether these observations could be mechanistically explained by underlying changes in neural circuitry, we created a network model of MT. We found that a local imbalance of inhibition and excitation explained the observed firing rate changes. These results provide the first insights into functional implications of long-term plasticity in MT following V1 lesions.
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Affiliation(s)
- Maureen A Hagan
- Department of Physiology, Monash University, Clayton, VIC 3800, Australia.,Neuroscience Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia.,Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Clayton, VIC 3800, Australia
| | - Tristan A Chaplin
- Department of Physiology, Monash University, Clayton, VIC 3800, Australia.,Neuroscience Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia.,Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Clayton, VIC 3800, Australia.,Sainsbury Wellcome Centre for Neural Circuits and Behaviour, University College London, 25 Howland Street, London W1T 4JG, United Kingdom
| | - Krystel R Huxlin
- Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA
| | - Marcello G P Rosa
- Department of Physiology, Monash University, Clayton, VIC 3800, Australia.,Neuroscience Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia.,Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Clayton, VIC 3800, Australia
| | - Leo L Lui
- Department of Physiology, Monash University, Clayton, VIC 3800, Australia.,Neuroscience Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia.,Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Clayton, VIC 3800, Australia
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20
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Barbot A, Park WJ, Ng CJ, Zhang RY, Huxlin KR, Tadin D, Yoon G. Functional reallocation of sensory processing resources caused by long-term neural adaptation to altered optics. eLife 2021; 10:58734. [PMID: 33616034 PMCID: PMC7963487 DOI: 10.7554/elife.58734] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 02/10/2021] [Indexed: 11/21/2022] Open
Abstract
The eye’s optics are a major determinant of visual perception. Elucidating how long-term exposure to optical defects affects visual processing is key to understanding the capacity for, and limits of, sensory plasticity. Here, we show evidence of functional reallocation of sensory processing resources following long-term exposure to poor optical quality. Using adaptive optics to bypass all optical defects, we assessed visual processing in neurotypically-developed adults with healthy eyes and with keratoconus – a corneal disease causing severe optical aberrations. Under fully-corrected optical conditions, keratoconus patients showed altered contrast sensitivity, with impaired sensitivity for fine spatial details and better-than-typical sensitivity for coarse spatial details. Both gains and losses in sensitivity were more pronounced in patients experiencing poorer optical quality in their daily life and mediated by changes in signal enhancement mechanisms. These findings show that adult neural processing adapts to better match the changes in sensory inputs caused by long-term exposure to altered optics.
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Affiliation(s)
- Antoine Barbot
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, United States.,Center for Visual Science, University of Rochester, Rochester, United States
| | - Woon Ju Park
- Brain and Cognitive Sciences, University of Rochester, Rochester, United States.,Department of Psychology, University of Washington, Seattle, United States
| | - Cherlyn J Ng
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, United States.,Center for Visual Science, University of Rochester, Rochester, United States
| | - Ru-Yuan Zhang
- Brain and Cognitive Sciences, University of Rochester, Rochester, United States.,Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Institute of Psychology and Behavioral Science, Shanghai Jiao Tong University, Shanghai, China
| | - Krystel R Huxlin
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, United States.,Center for Visual Science, University of Rochester, Rochester, United States.,Brain and Cognitive Sciences, University of Rochester, Rochester, United States.,Department of Neuroscience, University of Rochester, Rochester, United States
| | - Duje Tadin
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, United States.,Center for Visual Science, University of Rochester, Rochester, United States.,Brain and Cognitive Sciences, University of Rochester, Rochester, United States.,Department of Neuroscience, University of Rochester, Rochester, United States
| | - Geunyoung Yoon
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, United States.,Center for Visual Science, University of Rochester, Rochester, United States
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21
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Abstract
PURPOSE OF REVIEW Homonymous visual field defects are a common sequela of stroke, and are assumed to be permanent within a few weeks of the event. Because consensus about the efficacy of rehabilitation is lacking, visual therapy is rarely prescribed. Here, we review current rehabilitation options and strategies in the translational pipeline that could change these perspectives. RECENT FINDINGS The mainstays of available therapy for homonymous visual defects are compensation training and substitution, which allow patients to better use their spared vision. However, early clinical studies suggest that vision can partially recover following intensive training inside the blind field. Research into the relative efficacy of different restorative approaches continues, providing insights into neurophysiologic substrates of recovery and its limitations. This, in turn, has led to new work examining the possible benefits of earlier intervention, advanced training procedures, noninvasive brain stimulation, and pharmacological adjuvants, all of which remain to be vetted through properly powered, randomized, clinical trials. SUMMARY Research has uncovered substantial visual plasticity after occipital strokes, suggesting that rehabilitative strategies for this condition should be more aggressive. For maximal benefit, poststroke vision-restorative interventions should begin early, and in parallel with strategies that optimize everyday use of an expanding field of view.
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Affiliation(s)
| | - Steven E Feldon
- Flaum Eye Institute
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Krystel R Huxlin
- Flaum Eye Institute
- Center for Visual Science, University of Rochester, Rochester, NY, USA
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22
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Saionz EL, Tadin D, Melnick MD, Huxlin KR. Functional preservation and enhanced capacity for visual restoration in subacute occipital stroke. Brain 2021; 143:1857-1872. [PMID: 32428211 DOI: 10.1093/brain/awaa128] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/30/2020] [Accepted: 03/01/2020] [Indexed: 01/18/2023] Open
Abstract
Stroke damage to the primary visual cortex (V1) causes a loss of vision known as hemianopia or cortically-induced blindness. While perimetric visual field improvements can occur spontaneously in the first few months post-stroke, by 6 months post-stroke, the deficit is considered chronic and permanent. Despite evidence from sensorimotor stroke showing that early injury responses heighten neuroplastic potential, to date, visual rehabilitation research has focused on patients with chronic cortically-induced blindness. Consequently, little is known about the functional properties of the post-stroke visual system in the subacute period, nor do we know if these properties can be harnessed to enhance visual recovery. Here, for the first time, we show that 'conscious' visual discrimination abilities are often preserved inside subacute, perimetrically-defined blind fields, but they disappear by ∼6 months post-stroke. Complementing this discovery, we now show that training initiated subacutely can recover global motion discrimination and integration, as well as luminance detection perimetry, just as it does in chronic cortically-induced blindness. However, subacute recovery was attained six times faster; it also generalized to deeper, untrained regions of the blind field, and to other (untrained) aspects of motion perception, preventing their degradation upon reaching the chronic period. In contrast, untrained subacutes exhibited spontaneous improvements in luminance detection perimetry, but spontaneous recovery of motion discriminations was never observed. Thus, in cortically-induced blindness, the early post-stroke period appears characterized by gradual-rather than sudden-loss of visual processing. Subacute training stops this degradation, and is far more efficient at eliciting recovery than identical training in the chronic period. Finally, spontaneous visual improvements in subacutes were restricted to luminance detection; discrimination abilities only recovered following deliberate training. Our findings suggest that after V1 damage, rather than waiting for vision to stabilize, early training interventions may be key to maximize the system's potential for recovery.
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Affiliation(s)
- Elizabeth L Saionz
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA.,Medical Scientist Training Program, University of Rochester, Rochester, NY, USA
| | - Duje Tadin
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA.,Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA
| | - Michael D Melnick
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA.,Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA
| | - Krystel R Huxlin
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA.,Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA
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23
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Jeon KI, Huxlin KR. How scars shape the neural landscape: Key molecular mediators of TGF-β1's anti-neuritogenic effects. PLoS One 2020; 15:e0234950. [PMID: 33232327 PMCID: PMC7685464 DOI: 10.1371/journal.pone.0234950] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 11/02/2020] [Indexed: 01/19/2023] Open
Abstract
Following injury to the peripheral and central nervous systems, tissue levels of transforming growth factor (TGF)-β1 often increase, which is key for wound healing and scarring. However, active wound regions and scars appear to inhibit process outgrowth by regenerating neurons. We recently showed that corneal wound myofibroblasts block corneal nerve regeneration in vivo, and sensory neurite outgrowth in vitro in a manner that relies critically on TGF-β1. In turn, delayed, abnormal re-innervation contributes to long-term sensory dysfunctions of the ocular surface. Here, we exposed morphologically and biochemically-differentiated sensory neurons from the ND7/23 cell line to TGF-β1 to identify the intracellular signals regulating these anti-neuritogenic effects, contrasting them with those of Semaphorin(Sema)3A, a known inhibitor of neurite outgrowth. Neuronal morphology was quantified using phase-contrast imaging. Western blotting and specific inhibitors were then used to identify key molecular mediators. Differentiated ND7/23 cells expressed neuron-specific markers, including those involved in neurite extension and polarization. TGF-β1 increased phosphorylation of collapsin response mediator protein-2 (CRMP2), a molecule that is key for neurite extension. We now show that both glycogen synthase kinase (GSK)-3β and Smad3 modulate phosphorylation of CRMP2 after treatment with TGF-β1. GSK-3β appeared to exert a particularly strong effect, which could be explained by its ability to phosphorylate not only CRMP2, but also Smad3. In conclusion, TGF-β1's inhibition of neurite outgrowth in sensory neurons appears to be regulated through a highly-conserved signaling pathway, which involves the GSK-3β/CRMP-2 loop via both canonical and non-canonical mechanisms. It is hoped that by defining the signaling pathways that control neurite outgrowth in wound environments, it will become possible to identify optimal molecular targets to promote re-innervation following injury.
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Affiliation(s)
- Kye-Im Jeon
- The Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
- The Center for Visual Science, University of Rochester, Rochester, NY, United States of America
| | - Krystel R. Huxlin
- The Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
- The Center for Visual Science, University of Rochester, Rochester, NY, United States of America
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24
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Fromm CA, Murphy KE, Polonenko MJ, Maddox RK, Huxlin KR, Diaz GJ. The effect of auditory cues on visual learning in multisensory perceptual training in virtual reality. J Vis 2020. [DOI: 10.1167/jov.20.11.867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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25
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Dhakal KR, Walters S, McGregor JE, Schwarz C, Strazzeri JM, Aboualizadeh E, Bateman B, Huxlin KR, Hunter JJ, Williams DR, Merigan WH. Localized Photoreceptor Ablation Using Femtosecond Pulses Focused With Adaptive Optics. Transl Vis Sci Technol 2020; 9:16. [PMID: 32832223 PMCID: PMC7414617 DOI: 10.1167/tvst.9.7.16] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 04/09/2020] [Indexed: 02/03/2023] Open
Abstract
Purpose The development of new approaches to human vision restoration could be greatly accelerated with the use of nonhuman primate models; however, there is a paucity of primate models of outer retina degeneration with good spatial localization. To limit ablation to the photoreceptors, we developed a new approach that uses a near-infrared ultrafast laser, focused using adaptive optics, to concentrate light in a small focal volume within the retina. Methods In the eyes of eight anesthetized macaques, 187 locations were exposed to laser powers from 50 to 210 mW. Laser exposure locations were monitored for up to 18 months using fluorescein angiography (FA), optical coherence tomography (OCT), scanning laser ophthalmoscopy (SLO), adaptive optics scanning laser ophthalmoscope (AOSLO) reflectance imaging, two-photon excited fluorescence (TPEF) ophthalmoscopy, histology, and calcium responses of retinal ganglion cells. Results This method produced localized photoreceptor loss with minimal axial spread of damage to other retinal layers, verified by in-vivo structural imaging and histologic examination, although in some cases evidence of altered autofluorescence was found in the adjacent retinal pigment epithelium (RPE). Functional assessment using blood flow imaging of the retinal plexus and calcium imaging of the response of ganglion cells above the photoreceptor loss shows that inner retinal circuitry was preserved. Conclusions Although different from a genetic model of retinal degeneration, this model of localized photoreceptor loss may provide a useful testbed for vision restoration studies in nonhuman primates. Translational Relevance With this model, a variety of vision restoration methods can be tested in the non-human primate.
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Affiliation(s)
- Kamal R Dhakal
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Sarah Walters
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,The Institute of Optics, University of Rochester, Rochester, NY, USA
| | | | - Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | | | | | - Brittany Bateman
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Krystel R Huxlin
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,The Institute of Optics, University of Rochester, Rochester, NY, USA.,Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,The Institute of Optics, University of Rochester, Rochester, NY, USA.,Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - David R Williams
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - William H Merigan
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,Flaum Eye Institute, University of Rochester, Rochester, NY, USA
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26
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Jeon KI, Nehrke K, Huxlin KR. Semaphorin 3A potentiates the profibrotic effects of transforming growth factor-β1 in the cornea. Biochem Biophys Res Commun 2020; 521:333-339. [PMID: 31668808 DOI: 10.1016/j.bbrc.2019.10.107] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 10/12/2019] [Indexed: 11/16/2022]
Abstract
Corneal scarring is a major cause of blindness worldwide with few effective therapeutic options. Finding a treatment would be of tremendous public health benefit, but requires a thorough understanding of the complex interactions that underlie this phenomenon. Here, we tested the hypothesis that the large increase in expression of Semaphorin 3A (SEMA3A) in corneal wounds contributes to the development of stromal fibrosis. We first verified this increased expression in vivo, in a cat model of photorefractive keratectomy-induced corneal wounding. We then examined the impact of adding exogenous SEMA3A to cultured corneal fibroblasts, and assessed how this affected the ability of transforming growth factor-beta1 (TGF-β1) to induce their differentiation into myofibroblasts. Finally, we examined how siRNA knockdown of endogenous SEMA3A affected these same phenomena. We found exogenous SEMA3A to significantly potentiate TGF-β1's profibrotic effects, with only a minimal contribution from cell-intrinsic SEMA3A. Our results suggest a previously unrecognized interaction between SEMA3A and TGF-β1 in the wounded cornea, and a possible contribution of SEMA3A to the regulation of tissue fibrosis and remodeling in this transparent organ.
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Affiliation(s)
| | - Keith Nehrke
- Department of Medicine, University of Rochester, Rochester, NY, USA
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27
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Fahrenthold BK, Cavanaugh MR, Murphy A, Ajina S, Sahraie A, Bridge H, Huxlin KR. Effect of Visual Training on Optic Tract Degeneration after V1 Lesions. J Vis 2019. [DOI: 10.1167/19.15.35] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
| | | | - Allison Murphy
- Department of Neuroscience, University of Rochester Medical Center
| | - Sara Ajina
- Nuffield Department of Clinical Neurosciences, University of Oxford
| | | | - Holly Bridge
- Nuffield Department of Clinical Neurosciences, University of Oxford
| | - Krystel R. Huxlin
- Flaum Eye Institute, Center for Visual Science, University of Rochester Medical Center
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28
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Saionz EL, Melnick MD, Tadin D, Huxlin KR. Use it before you lose it: greater efficacy of visual training for recovering contrast sensitivity in subacute cortical blindness. J Vis 2019. [DOI: 10.1167/19.15.33] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Elizabeth L. Saionz
- Translational Biomedical Science Program, University of Rochester
- Medical Scientist Training Program, University of Rochester
- Flaum Eye Institute, University of Rochester
| | - Michael D. Melnick
- Dept. Brain and Cognitive Sciences, University of Rochester
- Flaum Eye Institute, University of Rochester
| | - Duje Tadin
- Dept. Brain and Cognitive Sciences, University of Rochester
- Flaum Eye Institute, University of Rochester
- Center for Visual Science; University of Rochester
| | - Krystel R. Huxlin
- Dept. Brain and Cognitive Sciences, University of Rochester
- Flaum Eye Institute, University of Rochester
- Center for Visual Science; University of Rochester
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29
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Heffer AM, Proaño J, Roztocil E, Phipps RP, Feldon SE, Huxlin KR, Sime PJ, Libby RT, Woeller CF, Kuriyan AE. The polyether ionophore salinomycin targets multiple cellular pathways to block proliferative vitreoretinopathy pathology. PLoS One 2019; 14:e0222596. [PMID: 31527897 PMCID: PMC6748436 DOI: 10.1371/journal.pone.0222596] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 09/02/2019] [Indexed: 11/21/2022] Open
Abstract
Proliferative vitreoretinopathy (PVR) is characterized by membranes that form in the vitreous cavity and on both surfaces of the retina, which results in the formation of tractional membranes that can cause retinal detachment and intrinsic fibrosis of the retina, leading to retina foreshortening. Currently, there are no pharmacologic therapies that are effective in inhibiting or preventing PVR formation. One of the key aspects of PVR pathogenesis is retinal pigment epithelial (RPE) cell epithelial mesenchymal transition (EMT). Here we show that the polyether ionophore compound salinomycin (SNC) effectively inhibits TGFβ-induced EMT of RPE cells. SNC blocks the activation of TGFβ-induced downstream targets alpha smooth muscle actin (αSMA) and collagen 1 (Col1A1). Additionally, SNC inhibits TGFβ-induced RPE cell migration and contraction. We show that SNC functions to inhibit RPE EMT by targeting both the pTAK1/p38 and Smad2 signaling pathways upon TGFβ stimulation. Additionally, SNC is able to inhibit αSMA and Col1A1 expression in RPE cells that have already undergone TGFβ-induced EMT. Together, these results suggest that SNC could be an effective therapeutic compound in both the prevention and treatment of PVR.
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Affiliation(s)
- Alison M. Heffer
- Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
- * E-mail: (AH); (AK); (CFW)
| | - Jacob Proaño
- Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
| | - Elisa Roztocil
- Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
| | - Richard P. Phipps
- Department of Environmental Medicine, University of Rochester, Rochester, NY, United States of America
| | - Steven E. Feldon
- Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
- Center for Visual Sciences, University of Rochester, Rochester, NY, United States of America
| | - Krystel R. Huxlin
- Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
- Center for Visual Sciences, University of Rochester, Rochester, NY, United States of America
| | - Patricia J. Sime
- Department of Medicine, University of Rochester, Rochester, NY, United States of America
| | - Richard T. Libby
- Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
- Center for Visual Sciences, University of Rochester, Rochester, NY, United States of America
| | - Collynn F. Woeller
- Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
- * E-mail: (AH); (AK); (CFW)
| | - Ajay E. Kuriyan
- Flaum Eye Institute, University of Rochester, Rochester, NY, United States of America
- Center for Visual Sciences, University of Rochester, Rochester, NY, United States of America
- * E-mail: (AH); (AK); (CFW)
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30
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Huxlin KR, Cavanaugh MR. Author response: Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness. Neurology 2019; 90:437. [PMID: 29483319 DOI: 10.1212/wnl.0000000000005024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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31
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Hindman HB, DeMagistris M, Callan C, McDaniel T, Bubel T, Huxlin KR. Impact of topical anti-fibrotics on corneal nerve regeneration in vivo. Exp Eye Res 2019; 181:49-60. [PMID: 30660507 PMCID: PMC6443430 DOI: 10.1016/j.exer.2019.01.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 01/11/2019] [Accepted: 01/14/2019] [Indexed: 12/12/2022]
Abstract
Recent work in vitro has shown that fibroblasts and myofibroblasts have opposing effects on neurite outgrowth by peripheral sensory neurons. Here, we tested a prediction from this work that dampening the fibrotic response in the early phases of corneal wound healing in vivo could enhance reinnervation after a large, deep corneal injury such as that induced by photorefractive keratectomy (PRK). Since topical steroids and Mitomycin C (MMC) are often used clinically for mitigating corneal inflammation and scarring after PRK, they were ideal to test this prediction. Twenty adult cats underwent bilateral, myopic PRK over a 6 mm optical zone followed by either: (1) intraoperative MMC (n = 12 eyes), (2) intraoperative prednisolone acetate (PA) followed by twice daily topical application for 14 days (n = 12 eyes), or (3) no post-operative treatment (n = 16 eyes). Anti-fibrotic effects of MMC and PA were verified optically and histologically. First, optical coherence tomography (OCT) performed pre-operatively and 2, 4 and 12 weeks post-PRK was used to assess changes in corneal backscatter reflectivity. Post-mortem immunohistochemistry was then performed at 2, 4 and 12 weeks post-PRK, using antibodies against α-smooth muscle actin (α-SMA). Finally, immunohistochemistry with antibodies against βIII-tubulin (Tuj-1) was performed in the same corneas to quantify changes in nerve distribution relative to unoperated, control cat corneas. Two weeks after PRK, untreated corneas exhibited the greatest amount of staining for α-SMA, followed by PA-treated and MMC-treated eyes. This was matched by higher OCT-based stromal reflectivity values in untreated, than PA- and MMC-treated eyes. PA treatment appeared to slow epithelial healing and although normal epithelial thickness was restored by 12 weeks-post-PRK, intra-epithelial nerve length only reached ∼1/6 normal values in PA-treated eyes. Even peripheral cornea (outside the ablation zone) exhibited depressed intra-epithelial nerve densities after PA treatment. Stromal nerves were abundant under the α-SMA zone, but appeared to largely avoid it, creating an area of sub-epithelial stroma devoid of nerve trunks. In turn, this may have led to the lack of sub-basal and intra-epithelial nerves in the ablation zone of PA-treated eyes 4 weeks after PRK, and their continuing paucity 12 weeks after PRK. Intra-operative MMC, which sharply decreased α-SMA staining, was followed by rapid restoration of nerve densities in all corneal layers post-PRK compared to untreated corneas. Curiously, stromal nerves appeared unaffected by the development of large, stromal, acellular zones in MMC-treated corneas. Overall, it appears that post-PRK treatments that were most effective at reducing α-SMA-positive cells in the early post-operative period benefited nerve regeneration the most, resulting in more rapid restoration of nerve densities in all corneal layers of the ablation zone and of the corneal periphery.
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Affiliation(s)
- Holly B Hindman
- The Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA; Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
| | | | - Christine Callan
- The Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
| | - Thurma McDaniel
- The Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
| | - Tracy Bubel
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
| | - Krystel R Huxlin
- The Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA; Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA.
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32
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Yu D, Brown EB, Huxlin KR, Knox WH. Tissue effects of intra-tissue refractive index shaping (IRIS): insights from two-photon autofluorescence and second harmonic generation microscopy. Biomed Opt Express 2019; 10:855-867. [PMID: 30800519 PMCID: PMC6377903 DOI: 10.1364/boe.10.000855] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 12/29/2018] [Accepted: 01/02/2019] [Indexed: 05/05/2023]
Abstract
Intra-tissue refractive index shaping (IRIS) is a novel, non-ablative form of vision correction by which femtosecond laser pulses are tightly focused into ocular tissues to induce localized refractive index (RI) change via nonlinear absorption. Here, we examined the effects of Blue-IRIS on corneal microstructure to gain insights into underlying mechanisms. Three-layer grating patterns were inscribed with IRIS ~180 µm below the epithelial surface of ex vivo rabbit globes using a 400 nm femtosecond laser. Keeping laser power constant at 82 mW in the focal volume, multiple patterns were written at different scan speeds. The largest RI change induced in this study was + 0.011 at 20 mm/s. After measuring the phase change profile of each inscribed pattern, two-photon excited autofluorescence (TPEF) and second harmonic generation (SHG) microscopy were used to quantify changes in stromal structure. While TPEF increased significantly with induced RI change, there was a noticeable suppression of SHG signal in IRIS treated regions. We posit that enhancement of TPEF was due to the formation of new fluorophores, while decreases in SHG were most likely due to degradation of collagen triple helices. All in all, the changes observed suggest that IRIS works by inducing a localized, photochemical change in collagen structure.
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Affiliation(s)
- Dan Yu
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Materials Science Program, University of Rochester, Rochester, NY 14627, USA
| | - Edward B. Brown
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Krystel R. Huxlin
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Wayne H. Knox
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Materials Science Program, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
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33
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Cavanaugh MR, Barbot A, Carrasco M, Huxlin KR. Feature-based attention potentiates recovery of fine direction discrimination in cortically blind patients. Neuropsychologia 2017; 128:315-324. [PMID: 29237554 DOI: 10.1016/j.neuropsychologia.2017.12.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 12/02/2017] [Accepted: 12/04/2017] [Indexed: 01/23/2023]
Abstract
Training chronic, cortically-blind (CB) patients on a coarse [left-right] direction discrimination and integration (CDDI) task recovers performance on this task at trained, blind field locations. However, fine direction difference (FDD) thresholds remain elevated at these locations, limiting the usefulness of recovered vision in daily life. Here, we asked if this FDD impairment can be overcome by training CB subjects with endogenous, feature-based attention (FBA) cues. Ten CB subjects were recruited and trained on CDDI and FDD with an FBA cue or FDD with a neutral cue. After completion of each training protocol, FDD thresholds were re-measured with both neutral and FBA cues at trained, blind-field locations and at corresponding, intact-field locations. In intact portions of the visual field, FDD thresholds were lower when tested with FBA than neutral cues. Training subjects in the blind field on the CDDI task improved FDD performance to the point that a threshold could be measured, but these locations remained impaired relative to the intact field. FDD training with neutral cues resulted in better blind field FDD thresholds than CDDI training, but thresholds remained impaired relative to intact field levels, regardless of testing cue condition. Importantly, training FDD in the blind field with FBA lowered FDD thresholds relative to CDDI training, and allowed the blind field to reach thresholds similar to the intact field, even when FBA trained subjects were tested with a neutral rather than FBA cue. Finally, FDD training appeared to also recover normal integration thresholds at trained, blind-field locations, providing an interesting double dissociation with respect to CDDI training. In summary, mechanisms governing FBA appear to function normally in both intact and impaired regions of the visual field following V1 damage. Our results mark the first time that FDD thresholds in CB fields have been seen to reach intact field levels of performance. Moreover, FBA can be leveraged during visual training to recover normal, fine direction discrimination and integration performance at trained, blind-field locations, potentiating visual recovery of more complex and precise aspects of motion perception in cortically-blinded fields.
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Affiliation(s)
- Matthew R Cavanaugh
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY 14642, USA; Neuroscience Graduate Program, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Antoine Barbot
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY 14642, USA
| | - Marisa Carrasco
- Department of Psychology and Center for Neural Science, New York University, New York, NY 10003, USA
| | - Krystel R Huxlin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY 14642, USA
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34
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Wozniak KT, Elkins N, Brooks DR, Savage DE, MacRae S, Ellis JD, Knox WH, Huxlin KR. Contrasting cellular damage after Blue-IRIS and Femto-LASIK in cat cornea. Exp Eye Res 2017; 165:20-28. [PMID: 28866013 DOI: 10.1016/j.exer.2017.08.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/17/2017] [Accepted: 08/28/2017] [Indexed: 11/25/2022]
Abstract
Blue-intra-tissue refractive index shaping (Blue-IRIS) is a new approach to laser refractive correction of optical aberrations in the eye, which alters the refractive index of the cornea rather than changing its shape. Before it can be implemented in humans, it is critical to establish whether and to what extent, Blue-IRIS damages the cornea. Here, we contrasted the impact of -1.5 D cylinder refractive corrections inscribed using either Blue-IRIS or femtosecond laser in-situ keratomileusis (femto-LASIK) on corneal cell viability. Blue-IRIS was used to write a -1.5 D cylinder gradient index (GRIN) lens over a 2.5 mm by 2.5 mm area into the mid-stromal region of the cornea in six freshly-enucleated feline eyes. The same correction (-1.5 D cylinder) was inscribed into another four cat eyes using femto-LASIK. Six hours later, all corneas were processed for histology and stained for terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) and p-γ-H2AX to label damaged cells. In Blue-IRIS-treated corneas, no tissue was removed and TUNEL-stained cells were confined to the laser focal zone in the stroma. In femto-LASIK, photoablation removed 14 μm of anterior stroma, but in addition, TUNEL-positive cells clustered across the femto-flap, the epithelium at the flap edges and the stroma below the ablation zone. Keratocytes positive for p-γ-H2AX were seen adjacent to all Blue-IRIS focal zones, but were completely absent from femto-LASIK-treated corneas. Unlike femto-LASIK, Blue-IRIS attains refractive correction in the cornea without tissue removal and only causes minimal, localized keratocyte death within the laser focal zones. In addition, Blue-IRIS induced DNA modifications associated with phosphorylation of γ-H2AX in keratocytes adjacent to the laser focal zones. We posit that this p-γ-H2AX response is related to alterations in chromatin structure caused by localized changes in osmolarity, a possible mechanism for the induced refractive index changes.
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Affiliation(s)
- Kaitlin T Wozniak
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Noah Elkins
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Daniel R Brooks
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Daniel E Savage
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA; Center for Visual Science, University of Rochester, Rochester, NY 14627, USA; Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | - Scott MacRae
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA; Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | - Jonathan D Ellis
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA; Department of Mechanical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Wayne H Knox
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA; Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Krystel R Huxlin
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA; Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA.
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Jeon KI, Phipps RP, Sime PJ, Huxlin KR. Antifibrotic Actions of Peroxisome Proliferator-Activated Receptor γ Ligands in Corneal Fibroblasts Are Mediated by β-Catenin-Regulated Pathways. Am J Pathol 2017; 187:1660-1669. [PMID: 28606794 DOI: 10.1016/j.ajpath.2017.04.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 03/30/2017] [Accepted: 04/05/2017] [Indexed: 01/08/2023]
Abstract
Wound healing after corneal injury typically involves fibrosis, with transforming growth factor β1 (TGF-β1) as one of its strongest mediators. A class of small molecules-peroxisome proliferator-activated receptor γ (PPARγ) ligands-exert potent antifibrotic effects in the cornea by blocking phosphorylation of p38 mitogen-activated protein kinase (MAPK). However, why this blocks fibrosis remains unknown. Herein, we show that PPARγ ligands (rosiglitazone, troglitazone, and 15-deoxy-Δ12,14-prostaglandin J2) decrease levels of β-catenin. We also show that β-catenin siRNA and the Wingless/integrated (Wnt) inhibitor pyrvinium block the ability of corneal fibroblasts to up-regulate synthesis of α-smooth muscle actin (α-SMA), collagen 1 (COL1), and fibronectin (FN) in response to TGF-β1. Activation of TGF-β receptors and p38 MAPK increased glycogen synthase kinase 3β (GSK3β) phosphorylation, whereas a chemical inhibitor of p38 MAPK (SB203580) reduced the phosphorylation of GSK3β, decreasing active β-catenin levels in both cytoplasmic and nuclear fractions. Finally, lithium chloride, a GSK3 inhibitor, also attenuated the TGF-β1-induced increase in α-SMA, COL1, and FN expression. All in all, our results suggest that TGF-β1 stimulation increases active β-catenin concentration in cultured corneal fibroblasts through p38 MAPK regulation of canonical Wnt/β-catenin signaling, increasing α-SMA, COL1, and FN synthesis. Thus, PPARγ ligands, by blocking TGF-β1-induced p38 MAPK phosphorylation, prevent increases in both total and active β-catenin through p38 MAPK-GSK3β signaling.
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Affiliation(s)
- Kye-Im Jeon
- Flaum Eye Institute, University of Rochester, Rochester, New York
| | - Richard P Phipps
- Flaum Eye Institute, University of Rochester, Rochester, New York; Department of Medicine, University of Rochester, Rochester, New York; Department of Environmental Medicine, University of Rochester, Rochester, New York
| | - Patricia J Sime
- Department of Medicine, University of Rochester, Rochester, New York; Department of Environmental Medicine, University of Rochester, Rochester, New York
| | - Krystel R Huxlin
- Flaum Eye Institute, University of Rochester, Rochester, New York; Center for Visual Science, University of Rochester, Rochester, New York.
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Saionz EL, Sahin B, Williams Z, Huxlin KR. Can training in the subacute post-stroke period generate greater visual recovery after V1 damage? J Vis 2017. [DOI: 10.1167/17.7.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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37
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Cavanaugh M, Barbot A, Carrasco M, Huxlin KR. Attentional cues potentiate full recovery of fine motion discrimination in cortical blindness. J Vis 2017. [DOI: 10.1167/17.7.57] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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38
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Barbot A, Huxlin KR, Tadin D, Yoon G. Neural compensation mechanisms following long-term adaptation to severe optical defects. J Vis 2017. [DOI: 10.1167/17.7.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Antoine Barbot
- Flaum Eye Institute, University of Rochester2Center for Visual Science, University of Rochester
| | - Krystel R Huxlin
- Flaum Eye Institute, University of Rochester2Center for Visual Science, University of Rochester3Brain and Cognitive Sciences, University of Rochester
| | - Duje Tadin
- Flaum Eye Institute, University of Rochester2Center for Visual Science, University of Rochester3Brain and Cognitive Sciences, University of Rochester
| | - Geunyoung Yoon
- Flaum Eye Institute, University of Rochester2Center for Visual Science, University of Rochester
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Wozniak KT, Gearhart SM, Savage DE, Ellis JD, Knox WH, Huxlin KR. Comparable change in stromal refractive index of cat and human corneas following blue-IRIS. J Biomed Opt 2017; 22:55007. [PMID: 28538957 PMCID: PMC5443415 DOI: 10.1117/1.jbo.22.5.055007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 05/08/2017] [Indexed: 06/07/2023]
Abstract
Blue intratissue refractive index shaping (blue-IRIS) is a method with potential to correct ocular refraction noninvasively in humans. To date, blue-IRIS has only ever been applied to cat corneas and hydrogels. To test the comparability of refractive index change achievable in cat and human tissues, we used blue-IRIS to write identical phase gratings in ex vivo feline and human corneas. Femtosecond pulses (400 nm) were focused ? 300 ?? ? m below the epithelial surface of excised cat and human corneas and scanned to write phase gratings with lines ? 1 ?? ? m wide, spaced 5 ?? ? m apart, using a scan speed of 5 ?? mm / s . Additional cat corneas were used to test writing at 3 and 7 ?? mm / s in order to document speed dependence of the refractive index change magnitude. The first-order diffraction efficiency was immediately measured and used to calculate the refractive index change attained. Our data show that blue-IRIS induces comparable refractive index changes in feline and human corneas, an essential requirement for further developing its use as a clinical vision correction technique.
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Affiliation(s)
- Kaitlin T. Wozniak
- University of Rochester, Institute of Optics, Rochester, New York, United States
| | - Sara M. Gearhart
- University of Rochester, Institute of Optics, Rochester, New York, United States
| | - Daniel E. Savage
- University of Rochester, Institute of Optics, Rochester, New York, United States
- University of Rochester, Center for Visual Science, Rochester, New York, United States
- University of Rochester, Flaum Eye Institute, Rochester, New York, United States
| | - Jonathan D. Ellis
- University of Rochester, Institute of Optics, Rochester, New York, United States
- University of Rochester, Department of Mechanical Engineering, Rochester, New York, United States
| | - Wayne H. Knox
- University of Rochester, Institute of Optics, Rochester, New York, United States
- University of Rochester, Center for Visual Science, Rochester, New York, United States
- University of Rochester, Flaum Eye Institute, Rochester, New York, United States
| | - Krystel R. Huxlin
- University of Rochester, Center for Visual Science, Rochester, New York, United States
- University of Rochester, Flaum Eye Institute, Rochester, New York, United States
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Cavanaugh MR, Huxlin KR. Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness. Neurology 2017; 88:1856-1864. [PMID: 28404802 PMCID: PMC5419988 DOI: 10.1212/wnl.0000000000003921] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/01/2017] [Indexed: 11/25/2022] Open
Abstract
Objective: To assess if visual discrimination training improves performance on visual perimetry tests in chronic stroke patients with visual cortex involvement. Methods: 24-2 and 10-2 Humphrey visual fields were analyzed for 17 chronic cortically blind stroke patients prior to and following visual discrimination training, as well as in 5 untrained, cortically blind controls. Trained patients practiced direction discrimination, orientation discrimination, or both, at nonoverlapping, blind field locations. All pretraining and posttraining discrimination performance and Humphrey fields were collected with online eye tracking, ensuring gaze-contingent stimulus presentation. Results: Trained patients recovered ∼108 degrees2 of vision on average, while untrained patients spontaneously improved over an area of ∼16 degrees2. Improvement was not affected by patient age, time since lesion, size of initial deficit, or training type, but was proportional to the amount of training performed. Untrained patients counterbalanced their improvements with worsening of sensitivity over ∼9 degrees2 of their visual field. Worsening was minimal in trained patients. Finally, although discrimination performance improved at all trained locations, changes in Humphrey sensitivity occurred both within trained regions and beyond, extending over a larger area along the blind field border. Conclusions: In adults with chronic cortical visual impairment, the blind field border appears to have enhanced plastic potential, which can be recruited by gaze-controlled visual discrimination training to expand the visible field. Our findings underscore a critical need for future studies to measure the effects of vision restoration approaches on perimetry in larger cohorts of patients.
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Abstract
The incidence of cortically induced blindness is increasing as our population ages. The major cause of cortically induced blindness is stroke affecting the primary visual cortex. While the impact of this form of vision loss is devastating to quality of life, the development of principled, effective rehabilitation strategies for this condition lags far behind those used to treat motor stroke victims. Here we summarize recent developments in the still emerging field of visual restitution therapy, and compare the relative effectiveness of different approaches. We also draw insights into the properties of recovered vision, its limitations and likely neural substrates. We hope that these insights will guide future research and bring us closer to the goal of providing much-needed rehabilitation solutions for this patient population.
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Affiliation(s)
- Michael D Melnick
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, NY, USA
| | - Duje Tadin
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, NY, USA The Flaum Eye Institute, University of Rochester, Rochester, NY, USA The Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Krystel R Huxlin
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, NY, USA The Flaum Eye Institute, University of Rochester, Rochester, NY, USA The Center for Visual Science, University of Rochester, Rochester, NY, USA
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Cavanaugh MR, Zhang R, Melnick MD, Das A, Roberts M, Tadin D, Carrasco M, Huxlin KR. Visual recovery in cortical blindness is limited by high internal noise. J Vis 2015; 15:9. [PMID: 26389544 DOI: 10.1167/15.10.9] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Damage to the primary visual cortex typically causes cortical blindness (CB) in the hemifield contralateral to the damaged hemisphere. Recent evidence indicates that visual training can partially reverse CB at trained locations. Whereas training induces near-complete recovery of coarse direction and orientation discriminations, deficits in fine motion processing remain. Here, we systematically disentangle components of the perceptual inefficiencies present in CB fields before and after coarse direction discrimination training. In seven human CB subjects, we measured threshold versus noise functions before and after coarse direction discrimination training in the blind field and at corresponding intact field locations. Threshold versus noise functions were analyzed within the framework of the linear amplifier model and the perceptual template model. Linear amplifier model analysis identified internal noise as a key factor differentiating motion processing across the tested areas, with visual training reducing internal noise in the blind field. Differences in internal noise also explained residual perceptual deficits at retrained locations. These findings were confirmed with perceptual template model analysis, which further revealed that the major residual deficits between retrained and intact field locations could be explained by differences in internal additive noise. There were no significant differences in multiplicative noise or the ability to process external noise. Together, these results highlight the critical role of altered internal noise processing in mediating training-induced visual recovery in CB fields, and may explain residual perceptual deficits relative to intact regions of the visual field.
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Abstract
Many studies have shown that training and testing conditions modulate specificity of visual learning to trained stimuli and tasks. In visually impaired populations, generalizability of visual learning to untrained stimuli/tasks is almost always reported, with contrast sensitivity (CS) featuring prominently among these collaterally-improved functions. To understand factors underlying this difference, we measured CS for direction and orientation discrimination in the visual periphery of three groups of visually-intact subjects. Group 1 trained on an orientation discrimination task with static Gabors whose luminance contrast was decreased as performance improved. Group 2 trained on a global direction discrimination task using high-contrast random dot stimuli previously used to recover motion perception in cortically blind patients. Group 3 underwent no training. Both forms of training improved CS with some degree of specificity for basic attributes of the trained stimulus/task. Group 1's largest enhancement was in CS around the trained spatial/temporal frequencies; similarly, Group 2's largest improvements occurred in CS for discriminating moving and flickering stimuli. Group 3 saw no significant CS changes. These results indicate that CS improvements may be a natural consequence of multiple forms of visual training in visually intact humans, albeit with some specificity to the trained visual domain(s).
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Abstract
While we know that humans are extremely sensitive to optic flow information about direction of heading, we do not know how they integrate information across the visual field. We adapted the standard cue perturbation paradigm to investigate how young adult observers integrate optic flow information from different regions of the visual field to judge direction of heading. First, subjects judged direction of heading when viewing a three-dimensional field of random dots simulating linear translation through the world. We independently perturbed the flow in one visual field quadrant to indicate a different direction of heading relative to the other three quadrants. We then used subjects' judgments of direction of heading to estimate the relative influence of flow information in each quadrant on perception. Human subjects behaved similarly to the ideal observer in terms of integrating motion information across the visual field with one exception: Subjects overweighted information in the upper half of the visual field. The upper-field bias was robust under several different stimulus conditions, suggesting that it may represent a physiological adaptation to the uneven distribution of task-relevant motion information in our visual world.
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Jeon KI, Phipps RP, Sime PJ, Huxlin KR. Inhibitory effects of PPARγ ligands on TGF-β1-induced CTGF expression in cat corneal fibroblasts. Exp Eye Res 2015; 138:52-8. [PMID: 26142957 DOI: 10.1016/j.exer.2015.06.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/24/2015] [Accepted: 06/30/2015] [Indexed: 12/16/2022]
Abstract
Ligands of Peroxisome Proliferator Activated Receptor gamma (PPARγ) possess strong anti-fibrotic properties in the cornea and several other body tissues. In the cornea, we recently showed this class of molecules to prevent stromal myofibroblast differentiation partially by blocking the actions of p38 mitogen-activated protein kinase (MAPK). However, given the important role assigned to connective tissue growth factor (CTGF) in mediating corneal fibrosis, here we asked whether PPARγ ligands also act by affecting transforming growth factor-β (TGF-β) 1-induced expression of CTGF in cultured corneal fibroblasts. Corneal keratocytes were isolated from young, adult cats and early passage cells were exposed to TGF-β1 with or without the PPARγ ligands Rosiglitazone, Troglitazone and 15d-PGJ2. Western blots were used to assay levels of CTGF and alpha smooth muscle actin (αSMA), a marker of myofibroblast differentiation. CTGF siRNA demonstrated a critical role for CTGF in TGF-β1-mediated myofibroblast differentiation, while exogenously applied CTGF potentiated the pro-fibrogenic effects of TGF-β1. TGF-β1-mediated increases in CTGF and αSMA expression were strongly inhibited by all three PPARγ ligands tested, and by a c-jun N-terminal kinase (JNK) inhibitor. However, while extracellular signal-regulated kinase (ERK) 1/2, protein kinase B (AKT) and p38 MAPK inhibitors also blocked TGF-β1-induced αSMA induction, they did not dampen TGF-β1-induced increases in levels of CTGF. Thus, we conclude that PPARγ ligands block TGF-β1-induced increases in CTGF levels in cat corneal fibroblasts. They appear to do this in addition to their anti-fibrotic effect on p38 MAPK, providing a second intracellular pathway by which PPARγ ligands block αSMA induction.
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Affiliation(s)
- Kye-Im Jeon
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Richard P Phipps
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA; Department of Environmental Medicine, University of Rochester, Rochester, NY, USA; Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Patricia J Sime
- Department of Environmental Medicine, University of Rochester, Rochester, NY, USA; Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Krystel R Huxlin
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA; Center for Visual Science, University of Rochester, Rochester, NY, USA.
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Kavcic V, Triplett RL, Das A, Martin T, Huxlin KR. Role of inter-hemispheric transfer in generating visual evoked potentials in V1-damaged brain hemispheres. Neuropsychologia 2015; 68:82-93. [PMID: 25575450 DOI: 10.1016/j.neuropsychologia.2015.01.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 12/11/2014] [Accepted: 01/05/2015] [Indexed: 11/16/2022]
Abstract
Partial cortical blindness is a visual deficit caused by unilateral damage to the primary visual cortex, a condition previously considered beyond hopes of rehabilitation. However, recent data demonstrate that patients may recover both simple and global motion discrimination following intensive training in their blind field. The present experiments characterized motion-induced neural activity of cortically blind (CB) subjects prior to the onset of visual rehabilitation. This was done to provide information about visual processing capabilities available to mediate training-induced visual improvements. Visual Evoked Potentials (VEPs) were recorded from two experimental groups consisting of 9 CB subjects and 9 age-matched, visually-intact controls. VEPs were collected following lateralized stimulus presentation to each of the 4 visual field quadrants. VEP waveforms were examined for both stimulus-onset (SO) and motion-onset (MO) related components in postero-lateral electrodes. While stimulus presentation to intact regions of the visual field elicited normal SO-P1, SO-N1, SO-P2 and MO-N2 amplitudes and latencies in contralateral brain regions of CB subjects, these components were not observed contralateral to stimulus presentation in blind quadrants of the visual field. In damaged brain hemispheres, SO-VEPs were only recorded following stimulus presentation to intact visual field quadrants, via inter-hemispheric transfer. MO-VEPs were only recorded from damaged left brain hemispheres, possibly reflecting a native left/right asymmetry in inter-hemispheric connections. The present findings suggest that damaged brain hemispheres contain areas capable of responding to visual stimulation. However, in the absence of training or rehabilitation, these areas only generate detectable VEPs in response to stimulation of the intact hemifield of vision.
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Affiliation(s)
- Voyko Kavcic
- Institute of Gerontology, Wayne State University, Detroit, USA
| | - Regina L Triplett
- Hobart and William Smith Colleges, Geneva, NY, USA; Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Anasuya Das
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Tim Martin
- Dept. Psychology, Kennesaw State University, Kennesaw, GA, USA
| | - Krystel R Huxlin
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA; Center for Visual Science, University of Rochester, Rochester, NY, USA.
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Das A, Tadin D, Huxlin KR. Beyond blindsight: properties of visual relearning in cortically blind fields. J Neurosci 2014; 34:11652-64. [PMID: 25164661 PMCID: PMC4145170 DOI: 10.1523/jneurosci.1076-14.2014] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 06/13/2014] [Accepted: 07/07/2014] [Indexed: 11/21/2022] Open
Abstract
Damage to the primary visual cortex (V1) or its immediate afferents results in a dense scotoma, termed cortical blindness (CB). CB subjects have residual visual abilities, or blindsight, which allow them to detect and sometimes discriminate stimuli with high temporal and low spatial frequency content. Recent work showed that with training, discriminations in the blind field can become more reliable, and even reach consciousness. However, the narrow spatiotemporal bandwidth of blindsight limits its functional usefulness in everyday vision. Here, we asked whether visual training can induce recovery outside the spatiotemporal bandwidth of blindsight. Specifically, could human CB subjects learn to discriminate static, nonflickering stimuli? Can such learning transfer to untrained stimuli and tasks, and does double training with moving and static stimuli provide additional advantages relative to static training alone? We found CB subjects capable of relearning static orientation discriminations following single as well as double training. However, double training with complex, moving stimuli in a separate location was necessary to recover complex motion thresholds at locations trained with static stimuli. Subjects trained on static stimuli alone could only discriminate simple motion. Finally, both groups had approximately equivalent, incomplete recovery of fine orientation and direction discrimination thresholds, as well as contrast sensitivity. These results support two conclusions: (1) from a practical perspective, complex moving stimuli and double training may be superior training tools for inducing visual recovery in CB, and (2) the cortically blind visual system can relearn to perform a wider range of visual discriminations than predicted by blindsight alone.
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Affiliation(s)
- Anasuya Das
- University of Rochester Flaum Eye Institute, Rochester, New York 14642, Neuroscience Graduate Program, University of Rochester Medical Center, Rochester, New York 14642
| | - Duje Tadin
- University of Rochester Flaum Eye Institute, Rochester, New York 14642, Department of Brain & Cognitive Sciences and Center for Visual Science, University of Rochester, Rochester, New York 14627
| | - Krystel R Huxlin
- University of Rochester Flaum Eye Institute, Rochester, New York 14642, Department of Brain & Cognitive Sciences and Center for Visual Science, University of Rochester, Rochester, New York 14627
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Savage DE, Brooks DR, DeMagistris M, Xu L, MacRae S, Ellis JD, Knox WH, Huxlin KR. First demonstration of ocular refractive change using blue-IRIS in live cats. Invest Ophthalmol Vis Sci 2014; 55:4603-12. [PMID: 24985471 DOI: 10.1167/iovs.14-14373] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To determine the efficacy of intratissue refractive index shaping (IRIS) using 400-nm femtosecond laser pulses (blue light) for writing refractive structures directly into live cat corneas in vivo, and to assess the longevity of these structures in the eyes of living cats. METHODS Four eyes from two adult cats underwent Blue-IRIS. Light at 400 nm with 100-femtosecond (fs) pulses were tightly focused into the corneal stroma of each eye at an 80-MHz repetition rate. These pulses locally increased the refractive index of the corneal stroma via an endogenous, two-photon absorption process and were used to inscribe three-layered, gradient index patterns into the cat corneas. The optical effects of the patterns were then tracked using optical coherence tomography (OCT) and Shack-Hartmann wavefront sensing. RESULTS Blue-IRIS patterns locally changed ocular cylinder by -1.4 ± 0.3 diopters (D), defocus by -2.0 ± 0.5 D, and higher-order root mean square (HORMS) by 0.31 ± 0.04 μm at 1 month post-IRIS, without significant changes in corneal thickness or curvature. Refractive changes were maintained for the duration they were tracked, 12 months post-IRIS in one eye, and just more than 3 months in the remaining three eyes. CONCLUSIONS Blue-IRIS can be used to inscribe refractive structures into live cat cornea in vivo that are stable for at least 12 months, and are not associated with significant alterations in corneal thicknesses or radii of curvature. This result is a critical step toward establishing Blue-IRIS as a promising technique for noninvasive vision correction.
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Affiliation(s)
- Daniel E Savage
- The Institute of Optics, University of Rochester, Rochester, New York, United States Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Daniel R Brooks
- The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Margaret DeMagistris
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - Lisen Xu
- The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Scott MacRae
- Center for Visual Science, University of Rochester, Rochester, New York, United States Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - Jonathan D Ellis
- The Institute of Optics, University of Rochester, Rochester, New York, United States Department of Mechanical Engineering, University of Rochester, Rochester, New York, United States
| | - Wayne H Knox
- The Institute of Optics, University of Rochester, Rochester, New York, United States Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Krystel R Huxlin
- Center for Visual Science, University of Rochester, Rochester, New York, United States Flaum Eye Institute, University of Rochester, Rochester, New York, United States
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49
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Jeon KI, Kulkarni A, Woeller CF, Phipps RP, Sime PJ, Hindman HB, Huxlin KR. Inhibitory effects of PPARγ ligands on TGF-β1-induced corneal myofibroblast transformation. Am J Pathol 2014; 184:1429-45. [PMID: 24650561 DOI: 10.1016/j.ajpath.2014.01.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 01/08/2014] [Accepted: 01/16/2014] [Indexed: 01/11/2023]
Abstract
Corneal scarring, whether caused by trauma, laser refractive surgery, or infection, remains a significant problem for humans. Certain ligands for peroxisome proliferator-activated receptor gamma (PPARγ) have shown promise as antiscarring agents in a variety of body tissues. In the cornea, their relative effectiveness and mechanisms of action are still poorly understood. Here, we contrasted the antifibrotic effects of three different PPARγ ligands (15-deoxy-Δ12,14-prostaglandin J2, troglitazone, and rosiglitazone) in cat corneal fibroblasts. Western blot analyses revealed that all three compounds reduced transforming growth factor (TGF)-β1-driven myofibroblast differentiation and up-regulation of α-smooth muscle actin, type I collagen, and fibronectin expression. Because these effects were independent of PPARγ, we ascertained whether they occurred by altering phosphorylation of Smads 2/3, p38 mitogen-activated protein kinase, stress-activated protein kinase, protein kinase B, extracellular signal-regulated kinase, and/or myosin light chain 2. Only p38 mitogen-activated protein kinase phosphorylation was significantly inhibited by all three PPARγ ligands. Finally, we tested the antifibrotic potential of troglitazone in a cat model of photorefractive keratectomy-induced corneal injury. Topical application of troglitazone significantly reduced α-smooth muscle actin expression and haze in the stromal ablation zone. Thus, the PPARγ ligands tested here showed great promise as antifibrotics, both in vitro and in vivo. Our results also provided new evidence for the signaling pathways that may underlie these antifibrotic actions in corneal fibroblasts.
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Affiliation(s)
- Kye-Im Jeon
- Flaum Eye Institute, University of Rochester, Rochester, New York
| | - Ajit Kulkarni
- Department of Medicine, University of Rochester, Rochester, New York
| | - Collynn F Woeller
- Department of Environmental Medicine, University of Rochester, Rochester, New York
| | - Richard P Phipps
- Flaum Eye Institute, University of Rochester, Rochester, New York; Department of Medicine, University of Rochester, Rochester, New York; Department of Environmental Medicine, University of Rochester, Rochester, New York
| | - Patricia J Sime
- Department of Medicine, University of Rochester, Rochester, New York; Department of Environmental Medicine, University of Rochester, Rochester, New York
| | - Holly B Hindman
- Flaum Eye Institute, University of Rochester, Rochester, New York; Center for Visual Science, University of Rochester, Rochester, New York
| | - Krystel R Huxlin
- Flaum Eye Institute, University of Rochester, Rochester, New York; Center for Visual Science, University of Rochester, Rochester, New York.
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Weis AJ, Huxlin KR, Callan CL, DeMagistris MA, Hindman HB. Keratocyte apoptosis and not myofibroblast differentiation mark the graft/host interface at early time-points post-DSAEK in a cat model. PLoS One 2013; 8:e75623. [PMID: 24098706 PMCID: PMC3787047 DOI: 10.1371/journal.pone.0075623] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 08/16/2013] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To evaluate myofibroblast differentiation as an etiology of haze at the graft-host interface in a cat model of Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK). METHODS DSAEK was performed on 10 eyes of 5 adult domestic short-hair cats. In vivo corneal imaging with slit lamp, confocal, and optical coherence tomography (OCT) were performed twice weekly. Cats were sacrificed and corneas harvested 4 hours, and 2, 4, 6, and 9 days post-DSAEK. Corneal sections were stained with the TUNEL method and immunohistochemistry was performed for α-smooth muscle actin (α-SMA) and fibronectin with DAPI counterstain. RESULTS At all in vivo imaging time-points, corneal OCT revealed an increase in backscatter of light and confocal imaging revealed an acellular zone at the graft-host interface. At all post-mortem time-points, immunohistochemistry revealed a complete absence of α-SMA staining at the graft-host interface. At 4 hours, extracellular fibronectin staining was identified along the graft-host interface and both fibronectin and TUNEL assay were positive within adjacent cells extending into the host stroma. By day 2, fibronectin and TUNEL staining diminished and a distinct acellular zone was present in the region of previously TUNEL-positive cells. CONCLUSIONS OCT imaging consistently showed increased reflectivity at the graft-host interface in cat corneas in the days post-DSAEK. This was not associated with myofibroblast differentiation at the graft-host interface, but rather with apoptosis and the development of a subsequent acellular zone. The roles of extracellular matrix changes and keratocyte cell death and repopulation should be investigated further as potential contributors to the interface optical changes.
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Affiliation(s)
- Adam J Weis
- University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
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