How MT cells compute pattern motion

Tony Movshon, NYU

Neurons in MT (V5) are selective for the direction of visual motion.
In addition, many MT neurons are selective for the motion of complex
patterns independent of their component orientations, a behavior not
seen in earlier visual areas. Using a novel mutlicomponent
"hyperplaid" stimulus, we show that the responses of MT cells can be
captured by a linear model that operates not on the visual stimulus,
but on the afferent responses of a population of nonlinear V1 complex
cells. We fit this cascade model to responses of individual MT
neurons and show that it robustly predicts the separately-measured
responses of MT cells to gratings and plaids. The model captures the
full range of pattern motion selectivity found in MT. Cells that
signal pattern motion are distinguished by having broadly tuned
excitatory input from V1, strong motion opponent suppression, and a
tuned normalization at the V1 stage that may correspond to surround
suppression.