Responses of neurons in the medial superior temporal visual area to apparent motion stimuli in macaque monkeys

Churchland, A. K., Huang, X., Lisberger, S. G. (January 2007) Responses of neurons in the medial superior temporal visual area to apparent motion stimuli in macaque monkeys. Journal of Neurophysiology, 97 (1). pp. 272-282. ISSN 00223077 (ISSN)

DOI: 10.1152/jn.00941.2005


Monkeys fixated a stationary spot during presentation of dot textures that moved in apparent motion defined by the spatial and temporal separations, Δx and Δt, between successive flashes of each dot. For each neuron, we assessed the speed tuning for smooth motion (Δt = 2 or 4 ms) at speeds ≤128°/s and the effect of varying the value of Δt at speeds of 16 and 32°/s. Many medial superior temporal (MST) neurons, like middle temporal (MT) neurons, were tuned for the speed of smooth motion and showed decreases in firing rate as the value of Δt increased at a constant speed. A subset of MST neurons, however, showed monotonically increasing firing rates as a function of smooth stimulus speed and responses to apparent motion that paralleled a previously discovered illusion where estimates of target speed increase with the value of Δt. Opponent firing rate, defined as the difference between responses for motion in the preferred and opposite directions, peaked at values of Δt that were consistent with the behavioral illusion. Comparison with a new sample of MT neurons recorded with the same stimuli failed to reveal comparable effects. Attempts to map the population responses in MT and MST onto the behavioral illusion of increased speed succeeded by averaging the opponent response across MST neurons, but only by applying vector averaging to determine the preferred speed of the most active MT neurons. We suggest that a vector-averaging computation transforms MT's place code for target speed into the rate code of some MST neurons. Copyright © 2007 The American Physiological Society.

Item Type: Paper
Uncontrolled Keywords: animal cell animal experiment article brain nerve cell cell function cell motion cell population controlled study male monkey motoneuron nerve cell membrane potential nonhuman priority journal quantitative analysis stimulus response Action Potentials Animals Attention Macaca mulatta Motion Perception Neurons Orientation Photic Stimulation Psychomotor Performance Pursuit, Smooth Space Perception Temporal Lobe Time Factors Visual Cortex Visual Pathways
Subjects: organism description > animal behavior
organism description > animal > mammal > primates
organism description > animal behavior > vision
CSHL Authors:
Communities: CSHL labs > Churchland lab
Depositing User: CSHL Librarian
Date: January 2007
Date Deposited: 20 Mar 2012 15:05
Last Modified: 03 Dec 2014 15:04
PMCID: PMC2476927
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