Effect of microstimulation of the inferior temporal cortex on color judgment behavior

Within the anterior inferior temporal cortex (AIT) there is a cluster of color selective neurons whose activities correlate with color discrimination behavior. To examine the causal relationship between the activities of these neurons and behavior, we applied electrical microstimulation to modulate neuronal activities within the AIT. We trained monkeys to perform a color judgment task and evaluated the effect of microstimulation in terms of the horizontal shift of the psychometric function. We found large effects of microstimulation on color discrimination behavior, predominantly within a subregion of the AIT. The cortical extent where microstimulation modulated behavior correlated with the presence of color-selective neurons. Unexpectedly, the direction of the modulation of color judgment evoked by microstimulation correlated negatively with the preference of the neurons around the stimulation site. These results support the existence of an anterior inferior temporal color-selective area (AITC) and its causal relationship with the color perception of these animals.