Audio Cortical Processing in Blind Individuals

Abstract

This chapter focuses on the cortical processing of auditory spatial information in blindness. Research has demonstrated enhanced auditory processing in blind individuals, suggesting they compensate for lacking vision with greater sensitivity in other senses. A few years ago, we demonstrated severely impaired auditory precision in congenitally blind individuals when performing an auditory spatial metric task: participants’ thresholds for spatially bisecting three consecutive, spatially distributed sound sources were seriously compromised. Here we describe psychophysical and neural correlates of this deficit, and we show that the deficit disappears if blind individuals are presented with coherent spatio-temporal cues (short space associated with short time and vice versa). Instead, when the audio information presents incoherent spatio-temporal cues (short space associated with long time and vice versa), sighted individuals are unaffected by the perturbation while blind individuals are strongly attracted to the temporal cue. These results suggest that blind participants use temporal cues to make audio spatial estimations and that the visual cortex seems to have a functional role in these perceptual tasks. In the present chapter, we illustrate our hypothesis, suggesting that the lack of vision may drive construction of multisensory cortical network coding space based on temporal instead of spatial coordinates