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Behavioral/Systems/Cognitive Recent History of Stimulus Speeds Affects the Speed Tuning

Summary: Behavioral/Systems/Cognitive
Recent History of Stimulus Speeds Affects the Speed Tuning
of Neurons in Area MT
Anja Schlack,1 Bart Krekelberg,2 and Thomas D. Albright1
1Systems Neurobiology Laboratories, The Salk Institute for Biological Studies, La Jolla, California 92037, and 2Center for Molecular and Behavioral
Neuroscience, Rutgers University, Newark, New Jersey 07102
Visual motion processing plays a key role in enabling primates' successful interaction with their dynamic environments. Although in
natural environments the speed of visual stimuli continuously varies, speed tuning of neurons in the prototypical motion area MT has
traditionally been assessed with stimuli that moved at constant speeds. We investigated whether the representation of speed in a
continuously varying stimulus context differs from the representation of constant speeds. We recorded from individual MT neurons of
fixating macaques while stimuli moved either at a constant speed or in a linearly accelerating or decelerating manner. We found clear
tuning width of the speed tuning curves. These acceleration-dependent changes in response lead to an accurate representation of the
based on the constant speed response profiles. This model incorporated each cell's speed tuning and response adaptation dynamics and
accurately predicted the response to constant speeds as well as accelerating and decelerating stimuli. Because the response of the model
neurons had no explicit acceleration dependence, we conclude that speed-dependent adaptation creates a strong influence of temporal
context on the MT response and thereby results in the representation of acceleration signals.
Key words: adaptation; speed; acceleration; motion processing; area MT; tuning


Source: Albright, Tom - Vision Center Laboratory, Salk Institute for Biological Studies


Collections: Biology and Medicine