title: Changes in early cortical visual processing predict enhanced reactivity in deaf individuals.
abstract: Individuals with profound deafness rely critically on vision to interact with their environment. Improvement of visual performance as a consequence of auditory deprivation is assumed to result from cross-modal changes occurring in late stages of visual processing. Here we measured reaction times and event-related potentials (ERPs) in profoundly deaf adults and hearing controls during a speeded visual detection task, to assess to what extent the enhanced reactivity of deaf individuals could reflect plastic changes in the early cortical processing of the stimulus. We found that deaf subjects were faster than hearing controls at detecting the visual targets, regardless of their location in the visual field (peripheral or peri-foveal). This behavioural facilitation was associated with ERP changes starting from the first detectable response in the striate cortex (C1 component) at about 80 ms after stimulus onset, and in the P1 complex (100-150 ms). In addition, we found that P1 peak amplitudes predicted the response times in deaf subjects, whereas in hearing individuals visual reactivity and ERP amplitudes correlated only at later stages of processing. These findings show that long-term auditory deprivation can profoundly alter visual processing from the earliest cortical stages. Furthermore, our results provide the first evidence of a co-variation between modified brain activity (cortical plasticity) and behavioural enhancement in this sensory-deprived population.
authors: Department of Cognitive Sciences and Education, University of Trento, Trento, Italy. davidebottari@gmail.com
authors: Davide
authors: D
authors: Bottari
authors: Anne
authors: A
authors: Caclin
authors: Marie-Hélène
authors: MH
authors: Giard
authors: Francesco
authors: F
authors: Pavani
mesh_terms: D000293:Adolescent; D000328:Adult; D001519:Behavior / Q000502:physiology; D003638:Deafness / Q000503:physiopathology*; D005074:Evoked Potentials, Visual; D005260:Female; D006309:Hearing / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult