Abstract
Directing attention to one of two stimuli placed within a neuron's classical receptive field (CRF) biases the neuron's response to more closely resemble the response evoked when the attended stimulus appears alone. It is not known, however, how attention modulates responses when one stimulus is positioned in the center of the neuron's CRF and the other is positioned within the surround. To examine this question we trained two monkeys to attentively track 2 out of 4 square wave gratings as they moved along separate trajectories through the visual field. In the middle of each trial the stimuli paused, with one grating in the CRF center, one in the surround, and the other two in the opposite hemifield. We have previously found that with attention directed away (to stimuli in the opposite hemifield), the surround stimulus strongly suppresses the response to the center stimulus. Here we report evidence that this suppression can be modulated by attention. We find that, in some neurons, directing attention to the surround stimulus can magnify surround suppression, and that attention to the center stimulus can reduce surround suppression.
Support Contributed By: NSF graduate research fellowship (K.S.), NIH training grant in cognitive neuroscience (J.M.), NEI 5Ro1EY13802 (J.R.)