Responses of MT and MST neurons to one and two moving objects in the
receptive field..
G. H. Recanzone, R.H. Wurtz and U. Schwarz.
Laboratory of Sensorimotor Research, National Eye Institute, National
Institutes of Health, Bethesda, MD 20892 and Center for Neuroscience and
Section of Neurobiology, Physiology & Behavior, University of California at
Davis, Davis, CA 95616.
APStracts 4:199N, 1997.
ABSTRACT
To test the effects of complex visual motion stimuli on the responses of
single neurons in areas MT and MST of the macaque monkey, we compared the
response elicited by one object in motion through the receptive field to the
response of two simultaneously presented objects moving in different
directions through the receptive field. There was an increased response to a
stimulus moving in a direction other than the best direction when it was
paired with a stimulus moving in the best direction. This increase was
significant for all directions of motion of the non-best stimulus, and the
magnitude of the difference increased as the difference in the directions of
the two stimuli increased. The magnitude of the increased response was
directly related to the relative responses of the neurons to the best and non-
best stimuli presented in isolation. Similarly, there was a decreased response
to a stimulus moving in a non-null direction when it was paired with a
stimulus moving in the null direction. This decreased response in MT did not
reach significance unless the second stimulus added to the null direction
moved in the best direction, whereas in MST the decrease was significant when
the second stimulus direction differed from the null by 90 degrees or more.
Further analysis showed that the two-object responses were better predicted by
taking the averaged response of the neuron to the two single-object stimuli
than by summation, multiplication, or vector addition of the responses to each
of the two single-object stimuli.
Received 14 April 1997; accepted in final form 22 August 1997.
APS Manuscript Number J303-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 28 August 1997