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.

Synchronization to auditory and visual rhythms in hearing and deaf individuals

“…First, the results provide evidence that cross-modal plasticity effects are not limited to attentional changes in the visual periphery and are consistent with recent research showing enhanced visual “reactivity” in deaf individuals (Bottari et al, 2010; 2011). Second, the results show that auditory deprivation during childhood does not lead to impaired temporal processing of rhythmic visual stimuli.…”

“…On the one hand, auditory deprivation has been shown to enhance aspects of visual processing, e.g., visual motion detection (Bavelier et al, 2001), attention to the visual periphery (Proksch & Bavelier, 2002), and speed of reaction to visual stimuli (Bottari, Caclin, Giard, & Pavani, 2011). In particular, deaf individuals are faster and more accurate at detecting the direction of motion of a stimulus presented in the visual periphery (e.g., Neville & Lawson, 1987), although deaf and hearing groups do not differ in coherent motion discrimination thresholds (e.g., Bosworth & Dobkins, 2002).…”

“…In particular, deaf individuals are faster and more accurate at detecting the direction of motion of a stimulus presented in the visual periphery (e.g., Neville & Lawson, 1987), although deaf and hearing groups do not differ in coherent motion discrimination thresholds (e.g., Bosworth & Dobkins, 2002). Deaf individuals are also faster to detect abrupt visual onsets (Bottari et al, 2011; Bottari, Nava, Ley, & Pavani, 2010; Loke & Song, 1991). Several researchers have proposed that enhanced visual abilities in deaf individuals stem from selective changes in the “motion pathway” along dorsal visual stream (e.g., Armstrong, Neville, Hillyard, & Mitchell, 2002; Bavelier et al, 2006; Neville & Bavelier, 2002).…”

“…Several researchers have proposed that enhanced visual abilities in deaf individuals stem from selective changes in the “motion pathway” along dorsal visual stream (e.g., Armstrong, Neville, Hillyard, & Mitchell, 2002; Bavelier et al, 2006; Neville & Bavelier, 2002). Recent evidence has also suggested that behavioral changes in visual processing are associated with altered neural responses in striate cortex (Bottari et al, 2011) as well as in primary auditory cortex (Scott, Karns, Dow, Stevens, & Neville, 2014). It is possible that greater sensitivity to motion direction and to visual onsets could improve visuomotor rhythmic synchronization to a moving and/or a flashing visual stimulus, perhaps to the level of auditory synchronization observed for hearing individuals.…”

Enhanced audio–visual interactions in the auditory cortex of elderly cochlear-implant users

“…This reorganization may allow superior visual abilities in CI users. Likewise, cross-modal reorganization in the auditory cortex and enhanced RTs to visual stimuli have been reported in deaf individuals (Bottari et al, , 2011Finney et al, 2003Finney et al, , 2001Hauthal et al, 2013;Heimler and Pavani, 2014). Given that deafness is also experienced by CI users (before implantation), these individuals may develop specific compensatory strategies to overcome auditory deprivation.…”