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Musz E, Loiotile R, Chen J, Cusack R, Bedny M. Naturalistic stimuli reveal a sensitive period in cross modal responses of visual cortex: Evidence from adult-onset blindness. Neuropsychologia 2022; 172:108277. [PMID: 35636634 PMCID: PMC9648859 DOI: 10.1016/j.neuropsychologia.2022.108277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 04/28/2022] [Accepted: 05/25/2022] [Indexed: 01/31/2023]
Abstract
How do life experiences impact cortical function? In people who are born blind, the "visual" cortices are recruited during nonvisual tasks, such as Braille reading and sound localization. Do visual cortices have a latent capacity to respond to nonvisual information throughout the lifespan? Alternatively, is there a sensitive period of heightened plasticity that makes visual cortex repurposing especially possible during childhood? To gain insight into these questions, we leveraged meaningful naturalistic auditory stimuli to simultaneously engage a broad range of cognitive domains and quantify cross-modal responses across congenitally blind (n = 22), adult-onset blind (vision loss >18 years-of-age, n = 14) and sighted (n = 22) individuals. During fMRI scanning, participants listened to two types of meaningful naturalistic auditory stimuli: excerpts from movies and a spoken narrative. As controls, participants heard the same narrative with the sentences shuffled and the narrative played backwards (i.e., meaningless sounds). We correlated the voxel-wise timecourses of different participants within condition and group. For all groups, all stimulus conditions induced synchrony in auditory cortex while only the narrative stimuli synchronized responses in higher-cognitive fronto-parietal and temporal regions. As previously reported, inter-subject synchrony in visual cortices was higher in congenitally blind than sighted blindfolded participants and this between-group difference was particularly pronounced for meaningful stimuli (movies and narrative). Critically, visual cortex synchrony was no higher in adult-onset blind than sighted blindfolded participants and did not increase with blindness duration. Sensitive period plasticity enables cross-modal repurposing in visual cortices.
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Affiliation(s)
- Elizabeth Musz
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Rita Loiotile
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Janice Chen
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Rhodri Cusack
- Trinity College Institute of Neuroscience, School of Psychology, Trinity College Dublin, Dublin, Ireland
| | - Marina Bedny
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
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Ankeeta A, Senthil Kumaran S, Saxena R, Dwivedi SN, Jagannathan NR. Visual Cortex Alterations in Early and Late Blind Subjects During Tactile Perception. Perception 2021; 50:249-265. [PMID: 33593140 DOI: 10.1177/0301006621991953] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Involvement of visual cortex varies during tactile perception tasks in early blind (EB) and late blind (LB) human subjects. This study explored differences in sensory motor networks associated with tactile task in EB and LB subjects and between children and adolescents. A total of 40 EB subjects, 40 LB subjects, and 30 sighted controls were recruited in two subgroups: children (6-12 years) and adolescents (13-19 years). Data were acquired using a 3T MR scanner. Analyses of blood oxygen level dependent (BOLD), functional connectivity (FC), correlation, and post hoc test for multiple comparisons were carried out. Difference in BOLD activity was observed in EB and LB groups in visual cortex during tactile perception, with increased FC of visual with dorsal attention and sensory motor networks in EB. EB adolescents exhibited increased connectivity with default mode and salience networks when compared with LB. Functional results correlated with duration of training, suggestive of better performance in EB. Alteration in sensory and visual networks in EB and LB correlated with duration of tactile training. Age of onset of blindness has an effect in cross-modal reorganization of visual cortex in EB and multimodal in LB in children and adolescents.
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Affiliation(s)
- A Ankeeta
- 28730All India Institute of Medical Sciences, India
| | | | - Rohit Saxena
- 28730All India Institute of Medical Sciences, India
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Improvements and Degradation to Spatial Tactile Acuity Among Blind and Deaf Individuals. Neuroscience 2020; 451:51-59. [PMID: 33065233 DOI: 10.1016/j.neuroscience.2020.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 09/24/2020] [Accepted: 10/01/2020] [Indexed: 11/22/2022]
Abstract
Cross-modal reorganization takes place for sensory cortices when there is no more primary input. For instance, the visual cortex in blind individuals which receives no visual input starts responding to auditory and tactile stimuli. Reorganization may improve or degrade processing of other modality inputs, via bottom-up compensational processes and top-down updating. In two experiments, we measured the spatial tactile response in a large sample of early- (N = 49) and late-blind (N = 51) individuals with varying levels of Braille proficiencies, and early-deaf (N = 69) with varying levels of hearing devices against separate hearing and sighted controls. Spatial tactile responses were measured using a standard gradient orientation task on two locations, the finger and tongue. Experiments show limited to no advantage in passive tactile response for blind individuals and degradation for deaf individuals at the finger. However, the use of hearing devices decreased the tactile impairment in early-deaf individuals. Also, no differences in age-related decline in both sensory-impaired groups were shown. Results show less tactile acuity differences between blind and sighted than previously reported, but supports recent reports of tactile impairment among the early-deaf.
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Maurer D, Ghloum JK, Gibson LC, Watson MR, Chen LM, Akins K, Enns JT, Hensch TK, Werker JF. Reduced perceptual narrowing in synesthesia. Proc Natl Acad Sci U S A 2020; 117:10089-10096. [PMID: 32321833 PMCID: PMC7211996 DOI: 10.1073/pnas.1914668117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Synesthesia is a neurologic trait in which specific inducers, such as sounds, automatically elicit additional idiosyncratic percepts, such as color (thus "colored hearing"). One explanation for this trait-and the one tested here-is that synesthesia results from unusually weak pruning of cortical synaptic hyperconnectivity during early perceptual development. We tested the prediction from this hypothesis that synesthetes would be superior at making discriminations from nonnative categories that are normally weakened by experience-dependent pruning during a critical period early in development-namely, discrimination among nonnative phonemes (Hindi retroflex /d̪a/ and dental /ɖa/), among chimpanzee faces, and among inverted human faces. Like the superiority of 6-mo-old infants over older infants, the synesthetic groups were significantly better than control groups at making all the nonnative discriminations across five samples and three testing sites. The consistent superiority of the synesthetic groups in making discriminations that are normally eliminated during infancy suggests that residual cortical connectivity in synesthesia supports changes in perception that extend beyond the specific synesthetic percepts, consistent with the incomplete pruning hypothesis.
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Affiliation(s)
- Daphne Maurer
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, ON, Canada L8S 4K1;
| | - Julian K Ghloum
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Laura C Gibson
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Marcus R Watson
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - Lawrence M Chen
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - Kathleen Akins
- Department of Philosophy, Simon Fraser University, Burnaby, BC, Canada V5A 1S6
| | - James T Enns
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - Takao K Hensch
- Center for Brain Science, Department of Molecular Cellular Biology, Harvard University, Cambridge, MA 02138
- Canadian Institute for Advanced Research, Toronto, ON, Canada M5G 1M1
- International Research Center for Neurointelligence, University of Tokyo Institutes for Advanced Study, Bunkyo-ku, Tokyo, Japan 113-0033
| | - Janet F Werker
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
- Canadian Institute for Advanced Research, Toronto, ON, Canada M5G 1M1
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Naturalistic Audio-Movies and Narrative Synchronize "Visual" Cortices across Congenitally Blind But Not Sighted Individuals. J Neurosci 2019; 39:8940-8948. [PMID: 31548238 DOI: 10.1523/jneurosci.0298-19.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 08/26/2019] [Accepted: 08/27/2019] [Indexed: 01/06/2023] Open
Abstract
How does developmental experience, as opposed to intrinsic physiology, shape cortical function? Naturalistic stimuli were used to elicit neural synchrony in individuals blind from birth (n = 18) and those who grew up with sight (n = 18). Blind and blindfolded sighted participants passively listened to three audio-movie clips, an auditory narrative, a sentence shuffled version of the narrative (maintaining language but lacking a plotline), and a version of the narrative backward (lacking both language and plot). For both groups, early auditory cortices were synchronized to a similar degree across stimulus types, whereas higher-cognitive temporoparietal and prefrontal areas were more synchronized by meaningful, temporally extended stimuli (i.e., audio movies and narrative). "Visual" cortices were more synchronized across blind than sighted individuals, but only for audio-movies and narrative. In the blind group, visual cortex synchrony was low for backward speech and intermediate for sentence shuffle. Meaningful auditory stimuli synchronize visual cortices of people born blind.SIGNIFICANCE STATEMENT Naturalistic stimuli engage cognitive processing at many levels. Here, we harnessed this richness to investigate the effect of experience on cortical function. We find that listening to naturalistic audio movies and narrative drives synchronized activity across "visual" cortices of blind, more so than sighted, individuals. Visual cortex synchronization varies with meaningfulness and cognitive complexity. Higher synchrony is observed for temporally extended meaningful stimuli (e.g., movies/narrative), intermediate for shuffled sentences, lowest for time varying complex noise. By contrast, auditory cortex was synchronized equally by meaningful and meaningless stimuli. In congenitally blind individuals most of visual cortex is engaged by meaningful naturalistic stimuli.
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Sozzi S, Decortes F, Schmid M, Crisafulli O, Schieppati M. Balance in Blind Subjects: Cane and Fingertip Touch Induce Similar Extent and Promptness of Stance Stabilization. Front Neurosci 2018; 12:639. [PMID: 30254565 PMCID: PMC6141713 DOI: 10.3389/fnins.2018.00639] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 08/28/2018] [Indexed: 12/14/2022] Open
Abstract
Subjects with low vision often use a cane when standing and walking autonomously in everyday life. One aim of this study was to assess differences in the body stabilizing effect produced by the contact of the cane with the ground or by the fingertip touch of a firm surface. Another aim was to estimate the promptness of balance stabilization (or destabilization) on adding (or withdrawing) the haptic input from cane or fingertip. Twelve blind subjects and two subjects with severe visual impairment participated in two experimental protocols while maintaining the tandem Romberg posture on a force platform. In one protocol, subjects lowered the cane to a second platform on the ground and lifted it in sequence at their own pace. In the other protocol, they touched an instrumented pad with the index finger and withdrew the finger from the pad in sequence. In both protocols, subjects were asked to exert a force not granting mechanical stabilization. Under steady-state condition, the finger touch or the contact of the cane with the ground significantly reduced (to ∼78% and ∼86%, respectively) the amplitude of medio-lateral oscillation of the centre of foot pressure (CoP). Oscillation then increased when haptic information was removed. The delay to the change in body oscillation after the haptic shift was longer for addition than withdrawal of the haptic information (∼1.4 s and ∼0.7 s, respectively; p < 0.001), but was not different between the two haptic conditions (finger and cane). Similar stabilizing effects of input from cane on the ground and from fingertip touch, and similar latencies to integrate haptic cue from both sources, suggest that the process of integration of the input for balance control is initiated by the haptic stimulus at the interface cane-hand. Use of a tool is as helpful as the fingertip input, and does not produce different stabilization. Further, the latencies to haptic cue integration (from fingertip or cane) are similar to those previously found in a group of sighted subjects, suggesting that integration delays for automatic balance stabilization are not modified by visual impairment. Haptic input from a tool is easily exploited by the neural circuits subserving automatic balance stabilization in blind people, and its use should be enforced by sensory-enhancing devices and appropriate training.
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Affiliation(s)
- Stefania Sozzi
- Centro Studi Attività Motorie, Istituti Clinici Scientifici Maugeri, Pavia, Italy
| | - Francesco Decortes
- Centro di Riabilitazione Visiva, Istituti Clinici Scientifici Maugeri, Pavia, Italy
| | - Monica Schmid
- Centro di Riabilitazione Visiva, Istituti Clinici Scientifici Maugeri, Pavia, Italy
| | - Oscar Crisafulli
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics and Maternal Child Health, University of Genoa, Genoa, Italy
| | - Marco Schieppati
- Department of Exercise and Sport Science, LUNEX International University of Health, Exercise and Sports, Differdange, Luxembourg
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Hirtz R, Weiss T, Huonker R, Witte OW. Impact of transcranial direct current stimulation on structural plasticity of the somatosensory system. J Neurosci Res 2018; 96:1367-1379. [PMID: 29876962 DOI: 10.1002/jnr.24258] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 04/22/2018] [Accepted: 04/23/2018] [Indexed: 01/21/2023]
Abstract
While there is a growing body of evidence regarding the behavioral and neurofunctional changes in response to the longitudinal delivery of transcranial direct current stimulation (tDCS), there is limited evidence regarding its structural effects. Therefore, the present study was intended to investigate the effect of repeatedly applied anodal tDCS over the primary somatosensory cortex on the gray matter (GM) and white matter (WM) compartment of the brain. Structural tDCS effects were, moreover, related to effects evidenced by functional imaging and behavioral assessment. tDCS was applied over the course of 5 days in 25 subjects with concomitant assessment of tactile acuity of the right and left index finger as well as imaging at baseline, after the last delivery of tDCS and at follow-up 4 weeks thereafter. Irrespective of the stimulation condition (anodal vs. sham), voxel-based morphometry revealed a behaviorally relevant decrease of GM in the precuneus co-localized with a functional change of its activity. Moreover, there was a decrease in GM of the bilateral lingual gyrus and the right cerebellum. Diffusion tensor imaging analysis showed an increase of fractional anisotropy exclusively in the tDCSanodal condition in the left frontal cortex affecting the final stretch of a somatosensory decision making network comprising the middle and superior frontal gyrus as well as regions adjacent to the genu of the corpus callosum. Thus, this is the first study in humans to identify structural plasticity in the GM compartment and tDCS-specific changes in the WM compartment in response to somatosensory learning.
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Affiliation(s)
- Raphael Hirtz
- Hans Berger Department of Neurology, Jena University Hospital, Friedrich Schiller University, Jena, Germany
- Pediatric Endocrinology and Diabetology, Essen University Hospital, Essen, Germany
| | - Thomas Weiss
- Department of Biological and Clinical Psychology, Friedrich Schiller University, Jena, Germany
| | - Ralph Huonker
- Brain Imaging Center, Hans Berger Department of Neurology, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Otto W Witte
- Hans Berger Department of Neurology, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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