Responses in area hMT+ reflect tuning for both auditory frequency and motion after blindness early in life

Abstract

Significance When individuals lose a sense early in life, widespread neural reorganization occurs. This extraordinary plasticity plays a critical role in allowing blind and deaf individuals to make better use of their remaining senses. Here, we show that area hMT+, selective for visual motion in sighted individuals, responds to auditory frequency as well as auditory motion after early blindness. Remarkably, auditory frequency tuning persisted in two adult sight-recovery subjects, despite their recovered ability to see visual motion. Thus, auditory frequency selectivity coexists with the neural architecture required for visual motion processing. In blind individuals, selectivity for auditory motion and frequency seems to exist within a conserved neural architecture capable of supporting analogous computations in the visual domain should vision be restored. Previous studies report that human middle temporal complex (hMT+) is sensitive to auditory motion in early-blind individuals. Here, we show that hMT+ also develops selectivity for auditory frequency after early blindness, and that this selectivity is maintained after sight recovery in adulthood. Frequency selectivity was assessed using both moving band-pass and stationary pure-tone stimuli. As expected, within primary auditory cortex, both moving and stationary stimuli successfully elicited frequency-selective responses, organized in a tonotopic map, for all subjects. In early-blind and sight-recovery subjects, we saw evidence for frequency selectivity within hMT+ for the auditory stimulus that contained motion. We did not find frequency-tuned responses within hMT+ when using the stationary stimulus in either early-blind or sight-recovery subjects. We saw no evidence for auditory frequency selectivity in hMT+ in sighted subjects using either stimulus. Thus, after early blindness, hMT+ can exhibit selectivity for auditory frequency. Remarkably, this auditory frequency tuning persists in two adult sight-recovery subjects, showing that, in these subjects, auditory frequency-tuned responses can coexist with visually driven responses in hMT+.