Sensitive period for a multi-modal response in human MT/MST.

Bedny, Konkle, Pelphrey, Saxe, & Pascual-Leone.

The middle temporal complex (MT/MST) is a brain region specialized for the perception of motion in the visual modality [1-4]. However, this specialization is modified by visual experience: following longstanding blindness, MT/MST responds to sound [5]. Recent evidence also suggests that the auditory response of MT/MST is selective for motion [6, 7]. The developmental timecourse of this plasticity is not known. To test for a sensitive period in MT/MST development, we compared MT/MST function in congenitally blind, late blind and sighted adults using fMRI. MT/MST responded to sound in congenitally blind adults, but not in late blind or sighted adults, and not in an individual who lost his vision between ages of 2 and 3 years. All blind adults had reduced functional connectivity between MT/MST and other visual regions. Functional connectivity was increased between MT/MST and lateral prefrontal areas in congenitally blind relative to sighted and late blind adults. These data suggest that early blindness affects the function of feedback projections from prefrontal cortex to MT/MST. We conclude that there is a sensitive period for visual specialization in MT/MST. During typical development, early visual experience either maintains or creates a vision-dominated response. Once established, this response profile is not altered by longstanding blindness.

Bedny, M., Konkle, T. Pelphrey, K., Saxe, R., & Pascual-Leone, A. (in press). Sensitive period for a vision-dominated response in human MT/MST. Current Biology.