Frontiers in Systems Neuroscience Systems Neuroscience
The role of the perceptual task on attentional effects is investigated by studying extracellular responses of individual neurons in area MT of two macaque monkeys and it is found that the modulation of fi ring rates by spatial attention and feature-based attention did not depend on whether the monkeys were attending to the motion or the color signal.
Abstract
cortical areas and between neurons within the same cortical area. The reasons for this variability are not well understood. A potential source of variability could be the extent to which the tuning properties of the recorded neurons can represent the stimulus properties relevant for the behavioral task (Maunsell, 2004). Accordingly, neurons with tuning properties optimally suited to solve the task at hand should show the strongest attentional effects. We investigated the role of the perceptual task on attentional effects by studying extracellular responses of individual neurons in area MT of two macaque monkeys. The monkeys were trained to attend either to the color or to the direction of motion of a random dot pattern (RDP). MT neurons are highly selective for processing of motion direction and speed, rather than color (Ungerleider and Mishkin, 1982; Felleman and Van Essen, 1991). Therefore, if attentional effects were strongest for optimally suited neurons, we would expect a stronger modulation of fi ring rates when attention was directed to the motion signal as compared to when it was directed to the color. We found that the modulation of fi ring rates by spatial attention and feature-based attention did not depend on whether the monkeys were attending to the motion or the color signal. We conclude that, under our task conditions, the degree to which the properties of the recorded neurons match the perceptual task at hand is not a likely explanation for the variability in the size of attentional effects.