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Fazzi E, Micheletti S, Calza S, Merabet L, Rossi A, Galli J. Early visual training and environmental adaptation for infants with visual impairment. Dev Med Child Neurol 2021; 63:1180-1193. [PMID: 34813110 PMCID: PMC8518055 DOI: 10.1111/dmcn.14865] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/23/2021] [Indexed: 12/04/2022]
Abstract
AIM To evaluate the effectiveness of early visual training and environmental adaptation on visual function and neurological development in infants with visual impairment. METHOD This was a pilot intervention clinical trial study. Thirty infants (mean age 5.9mo, SD 2.1mo, range 4-11mo; 16 males, 14 females) with peripheral visual impairment (PVI, n=15) or cerebral visual impairment (CVI, n=15) participated in a 6-month visual intervention programme. Thirty matched infants (mean age 6mo, SD 1.4mo, range 4-9mo; 18 males, 12 females) served as a comparison group. Primary outcome measures were visual acuity, contrast sensitivity, and qualitative ocular motor functions. Secondary outcomes were scores on the Griffiths Mental Developmental Scales (GMDS). RESULTS The treatment group showed a significant improvement in all the primary outcomes (p<0.01). The comparison group improved only in visual acuity and contrast sensitivity (p<0.01). The treatment group showed greater improvement than the comparison group in visual fixation (p=0.033) and smooth pursuit (p<0.01). The CVI subgroup showed greater improvement in visual acuity than the PVI subgroup (p<0.01). GMDS subscales of hand-eye coordination (p=0.01) and performance (p<0.01) increased in the treatment group, while the total score of the comparison group decreased, driven by language (p=0.039) and hand-eye coordination (p=0.025) subscales. INTERPRETATION Results suggest that, in infants with visual impairment, visual function and certain developmental outcomes improve in response to early visual training and environmental adaptation, in an interactive context. What this paper adds Early visual training and environmental adaptation are associated with enhanced visual acuity and smooth pursuit. Early visual training and environmental adaptation are associated with an improvement of neurological developmental outcome. Performance, hand-eye coordination, and language scores in Griffiths Mental Developmental Scales increase after visual training. After training, visual acuity improves more in infants with cerebral rather than anterior visual impairment. Type and complexity of visual impairment contribute to determine infants' response to training.
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Affiliation(s)
- Elisa Fazzi
- Department of Clinical and Experimental SciencesUniversity of BresciaBresciaItaly,Unit of Child Neurology and PsychiatryASST Spedali Civili of BresciaBresciaItaly
| | - Serena Micheletti
- Unit of Child Neurology and PsychiatryASST Spedali Civili of BresciaBresciaItaly
| | - Stefano Calza
- Unit of Biostatistics and BioinformaticsDepartment of Molecular and Translational MedicineUniversity of BresciaBresciaItaly
| | - Lotfi Merabet
- The Laboratory for Visual NeuroplasticityDepartment of OphthalmologyMassachusetts Eye and EarHarvard Medical SchoolBostonMAUSA
| | - Andrea Rossi
- Unit of Child Neurology and PsychiatryASST Spedali Civili of BresciaBresciaItaly
| | - Jessica Galli
- Department of Clinical and Experimental SciencesUniversity of BresciaBresciaItaly,Unit of Child Neurology and PsychiatryASST Spedali Civili of BresciaBresciaItaly
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Hoarau G, Merabet L, Knoeri J, Georgeon C, Poirier P, Borderie V, Brignole-Baudouin F, Bouheraoua N. Microsporidial keratoconjunctivitis: Report of two imported cases. J Fr Ophtalmol 2021; 44:e551-e554. [PMID: 34148704 DOI: 10.1016/j.jfo.2020.12.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 12/08/2020] [Indexed: 11/20/2022]
Affiliation(s)
- G Hoarau
- CHNO des Quinze-Vingts, Inserm-DGOS CIC 1423, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - L Merabet
- CHNO des Quinze-Vingts, Inserm-DGOS CIC 1423, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - J Knoeri
- CHNO des Quinze-Vingts, Inserm-DGOS CIC 1423, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - C Georgeon
- CHNO des Quinze-Vingts, Inserm-DGOS CIC 1423, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - P Poirier
- Laboratoire de parasitologie-mycologie, 3IHP, centre hospitalier universitaire Gabriel-Montpied, 58, rue Montalembert, 63000 Clermont-Ferrand, France; Université Clermont-Auvergne, CNRS UMR 6023, laboratoire Micro-organismes: génome et environnement, Clermont-Ferrand, France
| | - V Borderie
- CHNO des Quinze-Vingts, Inserm-DGOS CIC 1423, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France; Sorbonne université, Inserm, CNRS, Institut de la Vision, 17, rue Moreau, 75012 Paris, France
| | - F Brignole-Baudouin
- CHNO des Quinze-Vingts, Inserm-DGOS CIC 1423, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - N Bouheraoua
- CHNO des Quinze-Vingts, Inserm-DGOS CIC 1423, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France; Sorbonne université, Inserm, CNRS, Institut de la Vision, 17, rue Moreau, 75012 Paris, France.
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Keilty M, Houston KE, Collins C, Trehan R, Chen YT, Merabet L, Watts A, Pundlik S, Luo G. Inpatient Virtual Vision Clinic Improves Access to Vision Rehabilitation Before and During the COVID-19 Pandemic. Arch Rehabil Res Clin Transl 2021; 3:100100. [PMID: 33363279 PMCID: PMC7749728 DOI: 10.1016/j.arrct.2020.100100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE To describe and evaluate a secure video call system combined with a suite of iPad vision testing apps to improve access to vision rehabilitation assessment for inpatients. DESIGN Retrospective. SETTING Two acute care inpatient rehabilitation hospitals and 1 long-term acute care (LTAC) hospital. PARTICIPANTS Records of inpatients seen by the vision service. INTERVENTIONS Records from a 1-year telemedicine pilot performed at acute rehabilitation (AR) hospital 1 and then expanded to AR hospital 2 and LTAC hospital during coronavirus disease 2019 (COVID-19) were reviewed. In the virtual visits, an occupational therapist measured the patients' vision with the iPad applications and forwarded results to the off-site Doctor of Optometry (OD) for review prior to a video visit. The OD provided diagnosis and education, press-on prism application supervision, strategies and modifications, and follow-up recommendations. Providers completed the telehealth usability questionnaire (10-point scale). MAIN OUTCOME MEASURES Vision examinations per month at AR hospital 1 before and with telemedicine. RESULTS With telemedicine at AR hospital 1, mean visits per month significantly increased from 10.7±5 to 14.9±5 (P=.002). Prism was trialed in 40% of cases of which 83% were successful, similar to previously reported in-person success rates. COVID-19 caused only a marginal decrease in visits per month (P=.08) at AR1, whereas the site without an established program (AR hospital 2) had a 3-4 week gap in care while the program was initiated. Cases at the LTAC hospital tended to be more complex and difficult to manage virtually. The telehealth usability questionnaire median category scores were 7 for Ease of Use, 8 for Interface Quality, 6 for Reliability, and 9 for Satisfaction and Future Use. CONCLUSIONS The virtual vision clinic process improved inpatient access to eye and visual neurorehabilitation assessment before and during the COVID-19 quarantine and was well accepted by providers and patients.
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Key Words
- AR, acute rehabilitation
- COVID-19, coronavirus disease 2019
- EOM, extraocular movement
- IQR, interquartile range
- IRF, inpatient rehabilitation facility
- LTAC, long-term acute care
- OD, Doctor of Optometry
- OT, occupational therapist
- Pandemics
- Rehabilitation
- SARS-CoV-2, severe acute respiratory syndrome coronavirus 2
- Telemedicine
- Vision, ocular
- app, application
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Affiliation(s)
- Matthew Keilty
- Spaulding Rehabilitation Hospital Cape Cod, East Sandwich, Massachusetts
| | - Kevin E. Houston
- Spaulding Rehabilitation Hospital Cape Cod, East Sandwich, Massachusetts
- Spaulding Rehabilitation Hospital, Cambridge, Massachusetts
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, Massachusetts
- Optometry and Vision Rehabilitation Service, Massachusetts Eye and Ear, Boston, Massachusetts
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
- Schepens Eye Research Institute, Boston, Massachusetts
| | - Caroline Collins
- Spaulding Rehabilitation Hospital Cape Cod, East Sandwich, Massachusetts
| | - Ritika Trehan
- Spaulding Rehabilitation Hospital, Cambridge, Massachusetts
| | - Ya-Ting Chen
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, Massachusetts
| | - Lotfi Merabet
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, Massachusetts
- Optometry and Vision Rehabilitation Service, Massachusetts Eye and Ear, Boston, Massachusetts
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
- Schepens Eye Research Institute, Boston, Massachusetts
| | - Amy Watts
- Optometry and Vision Rehabilitation Service, Massachusetts Eye and Ear, Boston, Massachusetts
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
| | - Shrinivas Pundlik
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
- Schepens Eye Research Institute, Boston, Massachusetts
| | - Gang Luo
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
- Schepens Eye Research Institute, Boston, Massachusetts
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Duarte D, Bauer CCC, Pinto CB, Saleh Velez FG, Estudillo-Guerra MA, Pacheco-Barrios K, Gunduz ME, Crandell D, Merabet L, Fregni F. Cortical plasticity in phantom limb pain: A fMRI study on the neural correlates of behavioral clinical manifestations. Psychiatry Res Neuroimaging 2020; 304:111151. [PMID: 32738724 PMCID: PMC9394643 DOI: 10.1016/j.pscychresns.2020.111151] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 07/21/2020] [Accepted: 07/21/2020] [Indexed: 12/29/2022]
Abstract
The neural mechanism of phantom limb pain (PLP) is related to the intense brain reorganization process implicating plasticity after deafferentation mostly in sensorimotor system. There is a limited understanding of the association between the sensorimotor system and PLP. We used a novel task-based functional magnetic resonance imaging (fMRI) approach to (1) assess neural activation within a-priori selected regions-of-interested (motor cortex [M1], somatosensory cortex [S1], and visual cortex [V1]), (2) quantify the cortical representation shift in the affected M1, and (3) correlate these changes with baseline clinical characteristics. In a sample of 18 participants, we found a significantly increased activity in M1 and S1 as well as a shift in motor cortex representation that was not related to PLP intensity. In an exploratory analyses (not corrected for multiple comparisons), they were directly correlated with time since amputation; and there was an association between increased activity in M1 with a lack of itching sensation and V1 activation was negatively correlated with PLP. Longer periods of amputation lead to compensatory changes in sensory-motor areas; and itching seems to be a protective marker for less signal changes. We confirmed that PLP intensity is not associated with signal changes in M1 and S1 but in V1.
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Affiliation(s)
- D Duarte
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School. 96 13th Street, Charlestown, Boston, MA 02129, USA; Department of Psychiatry and Behavioural Neurosciences, McMaster University. 100 West 5th Street, Hamilton, ON L8N 3K7, Canada
| | - C C C Bauer
- McGovern Institute for Brain Research, MIT. 43 Vassar St, Cambridge, MA 02139, USA; Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM 3001, 76230 Juriquilla, Querétaro, 76230, México; Department of Psychology, Northeastern University, 805 Columbus Avenue, Boston, MA 02139, USA.
| | - C B Pinto
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School. 96 13th Street, Charlestown, Boston, MA 02129, USA
| | - F G Saleh Velez
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School. 96 13th Street, Charlestown, Boston, MA 02129, USA; University of Chicago Medical Center, Department of Neurology, University of Chicago. 5841 S Maryland Ave # C411, Chicago, IL 60637, USA
| | - M A Estudillo-Guerra
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School. 96 13th Street, Charlestown, Boston, MA 02129, USA
| | - K Pacheco-Barrios
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School. 96 13th Street, Charlestown, Boston, MA 02129, USA; Universidad San Ignacio de Loyola, Vicerrectorado de Investigación, Unidad de Investigación para la Generación y Síntesis de Evidencias en Salud. Lima, Peru. Av. La Fontana 750 Edificio El Cubo, La Molina - Perú
| | - M E Gunduz
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School. 96 13th Street, Charlestown, Boston, MA 02129, USA
| | - D Crandell
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School. 96 13th Street, Charlestown, Boston, MA 02129, USA
| | - L Merabet
- Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School. 243 Charles St, Boston, MA 02114, USA
| | - F Fregni
- Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School. 96 13th Street, Charlestown, Boston, MA 02129, USA; Massachusetts General Hospital, Harvard Medical School. 55 Fruit St, Boston, MA 02114, USA.
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Neil J, Kessal K, Merabet L, Kobal A, Bouhadiba S, Poilane C, Riancho L, Bury T, Baudouin C, Brignole-Baudouin F. IgE Ratio in Tears: A Predictive Tool of Ocular Allergic Inflammation. Ocul Immunol Inflamm 2020; 28:775-785. [PMID: 31411517 DOI: 10.1080/09273948.2019.1629462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [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: 10/26/2022]
Abstract
PURPOSE To demonstrate the tear IgE (measured/exuded) ratio (R) as a useful biological marker of ocular allergy in order to distinguish severe from less severe inflammatory status. METHODS Tear samples and sera from 78 ocular allergy patients and 19 control subjects were analyzed. Total IgE and albumin were measured for calculating the tear IgE-R defining two subgroups (SG) of samples: R ≥ 4-SG and R < 4-SG. Eosinophil cationic protein, Th1 and Th2 cytokines (IFN-γ, IL-4, -5, -6, -8 and -10) and protein electrophoretic profiles were also investigated in tears. RESULTS The R < 4-SG compared to the R ≥ 4-SG shows higher levels of tear albumin, eosinophil cationic protein, and Th1 and Th2 cytokines. Moreover, each subgroup presents a specific protein profile. CONCLUSION This study showed that an IgE-R lower than four must be carefully interpreted as a warning sign of a severe inflammatory context and should be also associated with an exploration of immunological profile.
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Affiliation(s)
- J Neil
- Medical Laboratory department, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DGOS CIC 1423 , Paris, France
| | - K Kessal
- Department of Ophthalmology III, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DHOS CIC 1423 , Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision , Paris, France
| | - L Merabet
- Medical Laboratory department, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DGOS CIC 1423 , Paris, France
| | - A Kobal
- Medical Laboratory department, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DGOS CIC 1423 , Paris, France
| | - S Bouhadiba
- Medical Laboratory department, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DGOS CIC 1423 , Paris, France
| | - C Poilane
- Medical Laboratory department, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DGOS CIC 1423 , Paris, France
| | - L Riancho
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision , Paris, France
| | - T Bury
- Department of Ophthalmology III, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DHOS CIC 1423 , Paris, France
| | - C Baudouin
- Department of Ophthalmology III, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DHOS CIC 1423 , Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision , Paris, France.,Department of Ophthalmology, Ambrroise paré Hospital, APHP, Boulogne-Billancourt, University of Versailles Saint-Quentin en Yvelines , Versailles, France
| | - F Brignole-Baudouin
- Medical Laboratory department, Quinze-Vingts National Ophthalmology Hospital, DHU Sight Restore, INSERM-DGOS CIC 1423 , Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision , Paris, France.,Faculté de Pharmacie de Paris, Université de Paris, Paris, France
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Kalia A, Yazzolino L, Merabet L, Sinha P. Top-Down Knowledge Improves Recognition of Noisy Haptic Patterns in the Blind and Sighted. J Vis 2016. [DOI: 10.1167/16.12.144] [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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Deer TR, Mekhail N, Petersen E, Krames E, Staats P, Pope J, Saweris Y, Lad SP, Diwan S, Falowski S, Feler C, Slavin K, Narouze S, Merabet L, Buvanendran A, Fregni F, Wellington J, Levy RM. The appropriate use of neurostimulation: stimulation of the intracranial and extracranial space and head for chronic pain. Neuromodulation Appropriateness Consensus Committee. Neuromodulation 2015; 17:551-70; discussion 570. [PMID: 25112890 DOI: 10.1111/ner.12215] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 04/17/2014] [Accepted: 05/13/2014] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The International Neuromodulation Society (INS) has identified a need for evaluation and analysis of the practice of neurostimulation of the brain and extracranial nerves of the head to treat chronic pain. METHODS The INS board of directors chose an expert panel, the Neuromodulation Appropriateness Consensus Committee (NACC), to evaluate the peer-reviewed literature, current research, and clinical experience and to give guidance for the appropriate use of these methods. The literature searches involved key word searches in PubMed, EMBASE, and Google Scholar dated 1970-2013, which were graded and evaluated by the authors. RESULTS The NACC found that evidence supports extracranial stimulation for facial pain, migraine, and scalp pain but is limited for intracranial neuromodulation. High cervical spinal cord stimulation is an evolving option for facial pain. Intracranial neurostimulation may be an excellent option to treat diseases of the nervous system, such as tremor and Parkinson's disease, and in the future, potentially Alzheimer's disease and traumatic brain injury, but current use of intracranial stimulation for pain should be seen as investigational. CONCLUSIONS The NACC concludes that extracranial nerve stimulation should be considered in the algorithmic treatment of migraine and other disorders of the head. We should strive to perfect targets outside the cranium when treating pain, if at all possible.
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Kalia A, Hopkins R, Jin D, Yazzolino L, Verma S, Merabet L, Phillips F, Sinha P. Perception of tactile graphics: embossings versus cutouts. Multisens Res 2014; 27:111-25. [PMID: 25296474 DOI: 10.1163/22134808-00002450] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Graphical information, such as illustrations, graphs, and diagrams, are an essential complement to text for conveying knowledge about the world. Although graphics can be communicated well via the visual modality, conveying this information via touch has proven to be challenging. The lack of easily comprehensible tactile graphics poses a problem for the blind. In this paper, we advance a hypothesis for the limited effectiveness of tactile graphics. The hypothesis contends that conventional graphics that rely upon embossings on two-dimensional surfaces do not allow the deployment of tactile exploratory procedures that are crucial for assessing global shape. Besides potentially accounting for some of the shortcomings of current approaches, this hypothesis also serves a prescriptive purpose by suggesting a different strategy for conveying graphical information via touch, one based on cutouts. We describe experiments demonstrating the greater effectiveness of this approach for conveying shape and identity information. These results hold the potential for creating more comprehensible tactile drawings for the visually impaired while also providing insights into shape estimation processes in the tactile modality.
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Bikson M, Rahman A, Datta A, Fregni F, Merabet L. High-resolution modeling assisted design of customized and individualized transcranial direct current stimulation protocols. Neuromodulation 2012; 15:306-15. [PMID: 22780230 DOI: 10.1111/j.1525-1403.2012.00481.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity currents facilitating or inhibiting spontaneous neuronal activity. tDCS is attractive since dose is readily adjustable by simply changing electrode number, position, size, shape, and current. In the recent past, computational models have been developed with increased precision with the goal to help customize tDCS dose. The aim of this review is to discuss the incorporation of high-resolution patient-specific computer modeling to guide and optimize tDCS. METHODS In this review, we discuss the following topics: 1) The clinical motivation and rationale for models of transcranial stimulation is considered pivotal in order to leverage the flexibility of neuromodulation; 2) the protocols and the workflow for developing high-resolution models; 3) the technical challenges and limitations of interpreting modeling predictions; and 4) real cases merging modeling and clinical data illustrating the impact of computational models on the rational design of rehabilitative electrotherapy. CONCLUSIONS Though modeling for noninvasive brain stimulation is still in its development phase, it is predicted that with increased validation, dissemination, simplification, and democratization of modeling tools, computational forward models of neuromodulation will become useful tools to guide the optimization of clinical electrotherapy.
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Affiliation(s)
- Marom Bikson
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY 10031, USA
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Brunoni AR, Nitsche MA, Bolognini N, Bikson M, Wagner T, Merabet L, Edwards DJ, Valero-Cabre A, Rotenberg A, Pascual-Leone A, Ferrucci R, Priori A, Boggio PS, Fregni F. Clinical research with transcranial direct current stimulation (tDCS): challenges and future directions. Brain Stimul 2012; 5:175-195. [PMID: 22037126 PMCID: PMC3270156 DOI: 10.1016/j.brs.2011.03.002] [Citation(s) in RCA: 885] [Impact Index Per Article: 73.8] [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: 11/07/2010] [Revised: 01/25/2011] [Accepted: 03/03/2011] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity, direct current to cortical areas facilitating or inhibiting spontaneous neuronal activity. In the past 10 years, tDCS physiologic mechanisms of action have been intensively investigated giving support for the investigation of its applications in clinical neuropsychiatry and rehabilitation. However, new methodologic, ethical, and regulatory issues emerge when translating the findings of preclinical and phase I studies into phase II and III clinical studies. The aim of this comprehensive review is to discuss the key challenges of this process and possible methods to address them. METHODS We convened a workgroup of researchers in the field to review, discuss, and provide updates and key challenges of tDCS use in clinical research. MAIN FINDINGS/DISCUSSION We reviewed several basic and clinical studies in the field and identified potential limitations, taking into account the particularities of the technique. We review and discuss the findings into four topics: (1) mechanisms of action of tDCS, parameters of use and computer-based human brain modeling investigating electric current fields and magnitude induced by tDCS; (2) methodologic aspects related to the clinical research of tDCS as divided according to study phase (ie, preclinical, phase I, phase II, and phase III studies); (3) ethical and regulatory concerns; and (4) future directions regarding novel approaches, novel devices, and future studies involving tDCS. Finally, we propose some alternative methods to facilitate clinical research on tDCS.
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Affiliation(s)
- Andre Russowsky Brunoni
- Department of Neurosciences and Behavior, Institute of Psychology, University of São Paulo, São Paulo, Brazil
| | - Michael A Nitsche
- Department of Clinical Neurophysiology, Georg-August University, Goettingen, Germany
| | - Nadia Bolognini
- Department of Psychology, University of Milano-Bicocca, Milan, Italy; Neuropsychological Laboratory, IRCCS Instituto Auxologico Italiano, Milan, Italy
| | - Marom Bikson
- The City College of City University of New York, New York, New York
| | - Tim Wagner
- Massachusetts Institute of Technology, Boston, Massachusetts
| | - Lotfi Merabet
- Massachusets Eye and Ear Infirmary, Harvard University, Boston, Massachusetts
| | | | | | - Alexander Rotenberg
- Department of Neurology, Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Roberta Ferrucci
- Centro Clinico per la Neurostimolazione, le Neurotecnologie ed i Disordini del Movimento, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Università degli Studi di Milano Dipartimento di Scienze Neurologiche, Milan, Italy
| | - Alberto Priori
- Centro Clinico per la Neurostimolazione, le Neurotecnologie ed i Disordini del Movimento, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Università degli Studi di Milano Dipartimento di Scienze Neurologiche, Milan, Italy
| | - Paulo Sergio Boggio
- Social and Cognitive Neuroscience Laboratory and Developmental Disorders Program, Center for Health and Biological Sciences, Mackenzie Prebyterian University, Sao Paulo, Brazil
| | - Felipe Fregni
- Laboratory of Neuromodulation, Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
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Volz M, Suarez-Contreras V, Mendonca M, Santos Pinheiro F, Merabet L, Fregni F. Modulatory Effects of Somatosensory Tasks on Pain Thresholds and Cortical Excitability (P01.172). Neurology 2012. [DOI: 10.1212/wnl.78.1_meetingabstracts.p01.172] [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: 11/15/2022] Open
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Cattoir V, Merabet L, Djibo N, Rioux C, Legrand P, Girou E, Lesprit P. Clinical impact of a real-time PCR assay for rapid identification of Staphylococcus aureus and determination of methicillin resistance from positive blood cultures. Clin Microbiol Infect 2011; 17:425-31. [PMID: 20384710 DOI: 10.1111/j.1469-0691.2010.03233.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The full identification and susceptibility profile of staphylococci from positive blood cultures (BCs) generally takes 24-48 h using phenotypic methods. The aim of this prospective study was to evaluate the clinical impact of a real-time PCR strategy for rapid identification of staphylococci and determination of methicillin resistance directly from positive BCs. During a 12-month period, 250 episodes of positive BCs with organism morphology resembling staphylococci were enrolled. Two strategies were compared: conventional (n = 128) using standard phenotypic methods or rapid (n = 122) using a real-time PCR assay that is able to detect specific genes of Staphylococcus aureus (nuc and sa442) and the encoding gene for methicillin resistance (mecA). Overall, 97 episodes (39%) were clinical-significant bloodstream infections. The prevalence of methicillin resistance of S. aureus was 24%. A favorable outcome (defined as clinical cure with resolution of signs and no evidence of recurrence or relapse at 12 weeks follow-up) was observed in similar proportions of episodes with (58%) or without (60%) PCR testing (p 0.8). In multivariate analyses, age and infection due to methicillin-susceptible S. aureus (adjusted OR 0.96, 95% CI 0.93-0.99; and adjusted OR 3.11, 95% CI 1.12-8.65, respectively) were the unique factors independently associated with a favorable outcome. Among the 153 episodes of contaminated BCs, similar proportions received unjustified antibiotic therapy (PCR strategy: 17%, conventional testing: 10%; p 0.33). In a setting with a moderate level of methicillin-resistant S. aureus and relatively high contamination of BCs, real-time PCR testing was not beneficial compared to conventional methods.
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Affiliation(s)
- V Cattoir
- Department of Bacteriology-Virology Infection Control Unit, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris, Université Paris 12, Créteil, France
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14
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Sánchez J, Sáenz M, Pascual-Leone A, Merabet L. Navigation for the Blind through Audio-Based Virtual Environments. Ext Abstr Hum Factors Computing Syst 2010; 2010:3409-3414. [PMID: 25505795 DOI: 10.1145/1753846.1753993] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
We present the design, development and an initial study changes and adaptations related to navigation that take place in the brain, by incorporating an Audio-Based Environments Simulator (AbES) within a neuroimaging environment. This virtual environment enables a blind user to navigate through a virtual representation of a real space in order to train his/her orientation and mobility skills. Our initial results suggest that this kind of virtual environment could be highly efficient as a testing, training and rehabilitation platform for learning and navigation.
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Affiliation(s)
- Jaime Sánchez
- Department of Computer Science, Center for Advanced Research in Education (CARE), University of Chile, Blanco Encalada 2120., Santiago, Chile
| | - Mauricio Sáenz
- Department of Computer Science, Center for Advanced Research in Education (CARE), University of Chile, Blanco Encalada 2120., Santiago, Chile
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School
| | - Lotfi Merabet
- Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School
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15
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Amedi A, Camprodon J, Merabet L, Meijer P, Pascual-Leone A. Towards closing the gap between visual neuroprostheses and sighted restoration: Insights from studying vision, cross-modal plasticity and sensory substitution. J Vis 2010. [DOI: 10.1167/6.13.12] [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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16
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Sánchez J, Sáenz M, Pascual-Leone A, Merabet L. Enhancing Navigation Skills through Audio Gaming. Ext Abstr Hum Factors Computing Syst 2010; 2010:3991-3996. [PMID: 25505796 DOI: 10.1145/1753846.1754091] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
We present the design, development and initial cognitive evaluation of an Audio-based Environment Simulator (AbES). This software allows a blind user to navigate through a virtual representation of a real space for the purposes of training orientation and mobility skills. Our findings indicate that users feel satisfied and self-confident when interacting with the audio-based interface, and the embedded sounds allow them to correctly orient themselves and navigate within the virtual world. Furthermore, users are able to transfer spatial information acquired through virtual interactions into real world navigation and problem solving tasks.
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Affiliation(s)
- Jaime Sánchez
- Department of Computer Science, Center for Advanced Research in Education (CARE), University of Chile, Blanco Encalada 2120. Santiago, Chile
| | - Mauricio Sáenz
- Department of Computer Science, Center for Advanced Research in Education (CARE), University of Chile, Blanco Encalada 2120. Santiago, Chile
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School
| | - Lotfi Merabet
- Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School
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17
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Boggio PS, Sultani N, Fecteau S, Merabet L, Mecca T, Pascual-Leone A, Basaglia A, Fregni F. Prefrontal cortex modulation using transcranial DC stimulation reduces alcohol craving: a double-blind, sham-controlled study. Drug Alcohol Depend 2008; 92:55-60. [PMID: 17640830 DOI: 10.1016/j.drugalcdep.2007.06.011] [Citation(s) in RCA: 222] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 06/03/2007] [Accepted: 06/11/2007] [Indexed: 01/18/2023]
Abstract
BACKGROUND Functional neuroimaging studies have shown that specific brain areas are associated with alcohol craving including the dorsolateral prefrontal cortex (DLPFC). We tested whether modulation of DLPFC using transcranial direct current stimulation (tDCS) could alter alcohol craving in patients with alcohol dependence while being exposed to alcohol cues. METHODS We performed a randomized sham-controlled study in which 13 subjects received sham and active bilateral tDCS delivered to DLPFC (anodal left/cathodal right and anodal right/cathodal left). For sham stimulation, the electrodes were placed at the same positions as in active stimulation; however, the stimulator was turned off after 30s of stimulation. Subjects were presented videos depicting alcohol consumption to increase alcohol craving. RESULTS Our results showed that both anodal left/cathodal right and anodal right/cathodal left significantly decreased alcohol craving compared to sham stimulation (p<0.0001). In addition, we found that following treatment, craving could not be further increased by alcohol cues. CONCLUSIONS Our findings showed that tDCS treatment to DLPFC can reduce alcohol craving. These findings extend the results of previous studies using noninvasive brain stimulation to reduce craving in humans. Given the relatively rapid suppressive effect of tDCS and the highly fluctuating nature of alcohol craving, this technique may prove to be a valuable treatment strategy within the clinical setting.
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Affiliation(s)
- Paulo S Boggio
- Nucleo de Neurociencias, Mackenzie University, Sao Paulo, SP, Brazil
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18
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Amedi A, Stern WM, Camprodon JA, Bermpohl F, Merabet L, Rotman S, Hemond C, Meijer P, Pascual-Leone A. Shape conveyed by visual-to-auditory sensory substitution activates the lateral occipital complex. Nat Neurosci 2007; 10:687-9. [PMID: 17515898 DOI: 10.1038/nn1912] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 04/27/2007] [Indexed: 11/08/2022]
Abstract
The lateral-occipital tactile-visual area (LOtv) is activated when objects are recognized by vision or touch. We report here that the LOtv is also activated in sighted and blind humans who recognize objects by extracting shape information from visual-to-auditory sensory substitution soundscapes. Recognizing objects by their typical sounds or learning to associate specific soundscapes with specific objects do not activate this region. This suggests that LOtv is driven by the presence of shape information.
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Affiliation(s)
- Amir Amedi
- Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, Massachusetts 02115, USA.
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19
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Abstract
We report a patient with long-standing blindness experiencing both simple and complex visual hallucinations secondary to a cortical arteriovenous malformation (AVM). The hallucinations were located in the right visual field corresponding to the contra-lateral site of cortical damage. This case contributes to our understanding of neurophysiological mechanisms underlying visual hallucinations and ongoing research investigating the phenomenology of hallucinations with respect to the cause and localization of neural damage.
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Affiliation(s)
- Arantxa Alfaro
- Servicio de Neurología, Hospital General Universitario, Alicante, Spain
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20
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Fernández E, Pelayo F, Romero S, Bongard M, Marin C, Alfaro A, Merabet L. Development of a cortical visual neuroprosthesis for the blind: the relevance of neuroplasticity. J Neural Eng 2005; 2:R1-12. [PMID: 16317227 DOI: 10.1088/1741-2560/2/4/r01] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Clinical applications such as artificial vision require extraordinary, diverse, lengthy and intimate collaborations among basic scientists, engineers and clinicians. In this review, we present the state of research on a visual neuroprosthesis designed to interface with the occipital visual cortex as a means through which a limited, but useful, visual sense could be restored in profoundly blind individuals. We review the most important physiological principles regarding this neuroprosthetic approach and emphasize the role of neural plasticity in order to achieve desired behavioral outcomes. While full restoration of fine detailed vision with current technology is unlikely in the immediate near future, the discrimination of shapes and the localization of objects should be possible allowing blind subjects to navigate in a unfamiliar environment and perhaps even to read enlarged text. Continued research and development in neuroprosthesis technology will likely result in a substantial improvement in the quality of life of blind and visually impaired individuals.
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Affiliation(s)
- E Fernández
- Instituto de Bioingeniería, Universidad Miguel Hernández, Elche, Spain.
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21
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Théoret H, Merabet L, Pascual-Leone A. Behavioral and neuroplastic changes in the blind: evidence for functionally relevant cross-modal interactions. ACTA ACUST UNITED AC 2005; 98:221-33. [PMID: 15477034 DOI: 10.1016/j.jphysparis.2004.03.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The study of blind individuals provides insight into the brain re-organization and behavioral compensations that occur following sensory deprivation. While behavioral studies have yielded conflicting results in terms of performance levels within the remaining senses, deafferentation of visual cortical areas through peripheral blindness results in clear neuroplastic changes. Most striking is the activation of occipital cortex in response to auditory and tactile stimulation. Indeed, parts of the "unimodal" visual cortex are recruited by other sensory modalities to process sensory information in a functionally relevant manner. In addition, a larger area of the sensorimotor cortex is devoted to the representation of the reading finger in blind Braille readers. The "visual" function of the deafferented occipital cortex is also altered, where transcranial magnetic stimulation-induced phosphenes can be elicited in only 20% of blind subjects. The neural mechanisms underlying these changes remain elusive but recent data showing rapid cross-modal plasticity in blindfolded, sighted subjects argue against the establishment of new connections to explain cross-modal interactions in the blind. Rather, latent pathways that participate in multisensory percepts in sighted subjects might be unmasked and may be potentiated in the event of complete loss of visual input. These issues have important implications for the development of visual prosthesis aimed at restoring some degree of vision in the blind.
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Affiliation(s)
- Hugo Théoret
- Laboratory for Magnetic Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
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22
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Théoret H, Kobayashi M, Merabet L, Wagner T, Tormos JM, Pascual-Leone A. Modulation of right motor cortex excitability without awareness following presentation of masked self-images. ACTA ACUST UNITED AC 2004; 20:54-7. [PMID: 15130589 DOI: 10.1016/j.cogbrainres.2004.01.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2004] [Indexed: 11/20/2022]
Abstract
The neural substrates of self-awareness have been studied with a variety of neurophysiological and behavioral tools. In the present study, unconscious modulation of corticospinal excitability following presentation of self-images was probed with transcranial magnetic stimulation (TMS). TMS-induced motor evoked potentials (MEP) were collected from the contralateral first dorsal interosseus (FDI) muscle while subjects viewed masked pictures of their own face. MEP amplitudes were compared to those obtained when pictures of strangers were masked. Masked self-images induced a relative increase in corticospinal excitability when TMS was applied to the right primary motor cortex. These results demonstrate the utility of TMS to probe unconscious processing and support the notion of hemispheric asymmetry in the processing of self-images.
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Affiliation(s)
- Hugo Théoret
- Laboratory for Magnetic Brain Stimulation, Behavioral Neurology Unit, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA.
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23
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Merabet L, Thut G, Murray B, Andrews J, Hsiao S, Pascual-Leone A. Feeling by sight or seeing by touch? Neuron 2004; 42:173-9. [PMID: 15066274 DOI: 10.1016/s0896-6273(04)00147-3] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2003] [Revised: 12/30/2003] [Accepted: 03/02/2004] [Indexed: 11/21/2022]
Abstract
We have addressed the role of occipital and somatosensory cortex in a tactile discrimination task. Sight-ed and congenitally blind subjects rated the roughness and distance spacing for a series of raised dot patterns. When judging roughness, intermediate dot spacings were perceived as being the most rough, while distance judgments generated a linear relation. Low-frequency rTMS applied to somatosensory cortex disrupted roughness without affecting distance judgments, while rTMS to occipital cortex disrupted distance but not roughness judgments. We also tested an early blind patient with bilateral occipital cortex damage. Her performance on the roughness determination task was normal; however, she was greatly impaired with distance judgments. The findings suggest a double-dissociation effect in which roughness and distance are primarily processed in somatosensory and occipital cortex, respectively. The differential effect of rTMS on task performance and corroborative clinical evidence suggest that occipital cortex is engaged in tactile tasks requiring fine spatial discrimination.
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Affiliation(s)
- Lotfi Merabet
- Laboratory for Magnetic Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
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24
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Affiliation(s)
- Felipe Fregni
- Laboratory for Magnetic Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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25
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Théoret H, Halligan E, Kobayashi M, Merabet L, Pascual-Leone A. Unconscious modulation of motor cortex excitability revealed with transcranial magnetic stimulation. Exp Brain Res 2004; 155:261-4. [PMID: 14745468 DOI: 10.1007/s00221-003-1820-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2003] [Accepted: 12/09/2003] [Indexed: 11/30/2022]
Abstract
The neuronal effects of sensory events that do not enter conscious awareness have been reported in numerous pathological conditions and in normal subjects. In the present study, unconscious modulation of corticospinal excitability was probed in healthy volunteers with transcranial magnetic stimulation (TMS). TMS-induced motor evoked potentials (MEPs) were collected from the first dorsal interosseus muscle while subjects performed a masked semantic priming task that has been shown to elicit covert motor cortex activations. Our data show that the amplitude of the MEPs is modulated by an unseen prime, in line with temporal patterns revealed with event related potentials. These data confirm previous reports showing specific motor neural responses associated with an unseen visual stimulus and establish TMS as a valuable tool in the study of the neural correlates of consciousness.
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Affiliation(s)
- Hugo Théoret
- Laboratory for Magnetic Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
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26
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Abstract
Thalamic nuclei have long been considered as passive relay stations for sensory signals en route to the cerebral cortex, where higher level processing occurs. In recent years, it has been proposed that thalamic nuclei may actively participate in the processing of specific information in conjunction with cortical areas. In support of this hypothesis, we recently discovered that neurons in the main extrageniculate visual nucleus, the pulvinar, exhibit higher-order visual properties that were, until now, only associated with higher-order cortical areas. Pulvinar neurons can indeed code the veridical direction of a moving plaid pattern, indicating that these cells can integrate ambiguous signals into a coherent percept. This finding as well as our demonstration that there are cortico-thalamo-cortical loops involved in complex motion analysis open promising avenues in unraveling the function of the pulvinar complex in normal vision.
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Affiliation(s)
- C Casanova
- Laboratoire des neurosciences de la vision, Ecole d'optométrie, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, PQ, H3C 3J7 Canada.
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27
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Abstract
The posteromedial lateral suprasylvian cortex represents a point of convergence between the geniculostriate and extrageniculostriate visual pathways. Given its purported role in motion analysis and the conflicting reports regarding the texture sensitivity of this area, we have investigated the response properties of cells in PMLS to moving texture patterns ("visual noise"). In contrast to previous reports, we have found that a large majority of cells (80.1%) responds to the motion of a texture pattern with sustained discharges. In general, responses to noise were more broadly tuned for direction compared to gratings; however, direction selectivity appeared more pronounced in response to noise. The majority of cells was selective for drift velocity of the noise pattern (mean optimal velocity: 26.7 degrees /s). Velocity tuning was comparable to that of its principal thalamic input, the lateral posterior pulvinar nucleus. In general, responsiveness of cells in the posteromedial lateral suprasylvian cortex increased with increasing texture element size, although some units were tuned to smaller element sizes than the largest presented. Finally, the magnitude of these noise responses was dependent on the area of the visual field stimulated. In general, a stimulus corresponding to roughly twice the size of the receptive field was required to elicit an equivalent half-maximal response to that for gratings. The results of this study indicate that the majority of cells in the posteromedial lateral suprasylvian cortex can be driven by the motion of a fine texture field, and highlight the importance of this area in motion analysis.
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Affiliation(s)
- L Merabet
- Ecole d'optométrie, Université de Montréal, CP 6128, succ. Centre-ville, Québec, H3C 3J7, Montréal, Canada
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28
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Abstract
Thalamic nuclei have long been regarded as passive relay stations for sensory information en route to higher level processing in the cerebral cortex. Recently, physiological and theoretical studies have reassessed the role of the thalamus and it has been proposed that thalamic nuclei may actively participate with cortical areas in processing specific information. In support of this idea, we now show that a subset of neurons in an extrageniculate visual nucleus, the lateral-posterior pulvinar complex, can signal the true direction of motion of a plaid pattern, indicating that thalamic cells can integrate different motion signals into a coherent moving percept. This is the first time that these computations have been found to occur outside the higher-order cortical areas. Our findings implicate extrageniculate cortico-thalamo-cortical loops in the dynamic processing of image motion, and, more generally, as basic computational modules involved in analysing specific features of complex visual scenes.
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Affiliation(s)
- L Merabet
- Visual Neuroscience Laboratory, School of Optometry, University of Montreal, Quebec, Canada
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29
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Merabet L, de Gasparo M, Casanova C. Dose-dependent inhibitory effects of angiotensin II on visual responses of the rat superior colliculus: AT1 and AT2 receptor contributions. Neuropeptides 1997; 31:469-81. [PMID: 9413025 DOI: 10.1016/s0143-4179(97)90042-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Angiotensin II (Ang II) has traditionally been regarded as a peripherally circulating and acting hormone involved in fluid homeostasis and blood pressure regulation. With the rather recent localization of Ang II receptors within the mammalian brain, renewed interest has emerged in the hope of elucidating the central impact and function of this hormone. One region that has been clearly demonstrated to express Ang II receptors is the superior colliculus (SC). This mesencephalic structure plays an important role in sensory visuomotor integration. Receptors for Ang II (of both the AT1 and AT2 subtypes) have been localized within the superficial layers of this structure, i.e. the areas that are visually responsive. In the hopes of characterizing the role of Ang II in the SC, we have attempted to physiologically activate these receptors in vivo and observe the effects of Ang II on visually evoked responses. In the attempt to identify the receptor subtype(s) responsible in mediating these effects, Ang II was injected concomitantly with selective receptor ligands. Experiments were performed on adult rats prepared in classical fashion for electrophysiological studies. Through microinjection of Ang II, and the simultaneous recording of visually evoked potentials to flash stimulation, we have observed that this peptide yields a strong suppressive effect on visual neuronal activity. By injecting Ang II at various concentrations (10(-3)-10(-10) M), we have further observed that the effects of this peptide express a dose-related dependency. Injection of Ang II in progressively more ventral layers yielded less pronounced effects, demonstrating physiologically the discrete localization of these receptors in the stratum griseum superficiale. Coinjection of Ang II with Losartan yielded a near complete blockade of Ang II suppressive effects, suggesting that AT1 receptors play a prominent role in mediating these responses. However, coinjection of Ang II with PD 123,319 yielded a slight, yet significant partial blockade. Coinjection of Ang II with both the AT1 and AT2 receptor antagonists yielded a complete blockade of the Ang II effect. Finally, some of the results suggest that the AT2 receptor ligand CGP 42,112 may possess agonist properties. Taken together, these findings suggest that the AT1 receptor is predominantly involved in mediating Ang II responses in the SC and there also appears to be some indication of AT2 receptor involvement. However, the underlying mechanisms (such as receptor interactions), the exact specificity of the ligands used, and the possibility of other receptor subtype implication have yet to be explored fully.
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Affiliation(s)
- L Merabet
- Département d'ophtalmologie, Faculté de médecine, Université de Sherbrooke, Québec, Canada
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30
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Abstract
Recent autoradiographic studies have revealed the presence of both AT1 and AT2 angiotensin II (AngII) receptor subtypes in the superficial layers of the rat superior colliculus (SC). We have investigated the effects of activating these receptors on visually evoked potentials (VEP) in the SC of adult rats. A recording injecting microelectrode filled with AngII was lowered into the superficial layers of the SC. AngII was injected at concentrations varying from 10(-4) to 10(-10) M. Injection of the peptide yielded a reduction in the amplitude of the VEP. This reduction usually occurred within 2-3 min following AngII injection with a 50% recovery of most of the signal 20-30 min thereafter. AngII did not modify the signal when injected in collicular layers ventral to the stratum opticum. Furthermore, concomitant injection of AngII with the specific AT, receptor antagonist Losartan failed to reduce the evoked response suggesting that the effects of AngII in the SC are likely mediated by AT1 receptors.
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Affiliation(s)
- L Merabet
- Department of Surgery-Ophthalmology, Faculty of Medicine, University of Sherbrooke, Quebec, Canada
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