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.