Abstract
We recently showed that hMT+ responses to auditory motion after early blindness are associated with subjects' decisions about auditory motion (VSS, 2012). Using fMRI pattern classification, in sighted individuals the perceived direction of motion for both coherent and ambiguous auditory motion stimuli was accurately categorized based on BOLD responses within the right planum temporale (PT); whereas within early blind individuals auditory motion decisions were only successfully categorized based on responses within hMT+, and could not be categorized based on responses within the right PT. Here we examined auditory motion direction processing in sight recovery subject MM, who acquired vision during adulthood after becoming blind at age three. Despite severe losses in acuity, he has no known deficits in his ability to process visual motion and he shows normal hMT+ responses to visual motion localizer stimuli. More than a decade after MM receiving visual input as an adult, we found the same double dissociation in fMRI pattern classification performance in MM as for early blind subjects: we were able to classify the perceived direction of auditory motion based on BOLD responses within hMT+ but not within PT. Thus, cross-modal motion responses consequent on blindness are unlikely to be the result of short-term unmasking, and are more plausibly the result of long-term developmental alterations in the functional specialization of hMT+.
Meeting abstract presented at VSS 2014