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Aldina A Reis, Catarina Mateus, João Castelhano, Eduardo Silva, Miguel Castelo-Branco; Patterns of Visual Cortical Responses Across Multiple Spatiotemporal Channels in Clinical and Pre-Clinical Models of Inherited Optic Neuropathies. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4124.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize neurophysiological responses across multiple spatiotemporal channels in clinical and pre-clinical stages of two inherited optic neuropathies, in order to investigate the impact of disease across multiple cortical locations, in central and paracentral vision.
We recorded high density visual evoked potentials with a SynAmps 2 system (Compumedics NeuroScan, Texas, USA) in two groups: 22 subjects from 13 families with Autosomal Dominant Optic Atrophy (ADOA) and 17 asymptomatic Leber Hereditary Optic Neuropathy (LHON) carriers of the same pedigree. An aged-matched control group was also included. Stimuli with distinct relative biases for the activation of magno or parvocellular pathways were presented mono and binocularly, in full-field or only in more peripheral visual locations. Parametric statistical analysis was performed using ANOVA (significance level: p ≤ 0.05). Paired t-Tests were used for within group analyses and Pearson coefficients used to assess correlation.
In visual cortex (occipital electrodes) of ADOA patients, evoked responses are considerably reduced for all types of stimulation as compared with controls (p ≤ 0.02), in particular for parvocellular responses. Interestingly, some binocular compensation could be found for paracentral parvo-biased stimuli in patients. Unlike in controls and in LHON carriers, response amplitudes differed into a lesser extent across posterior-anterior cortical regions.
Our results show cortical impairment of distinct spatiotemporal channels with distinct biases for parvo and magno driven responses with a distinct pattern of anterior visual response cortical preservation only in ADOA patients, suggesting either an anterior shift or compensation. Dominant impairment of parvo representations was partially compensated by binocular peripheral representations. Together, these findings suggest cortical reorganization of stimulus driven responses induced by visual impairment in this type of neuropathy.
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