Abstract
In normal vision, shifts of attention are usually followed by saccadic eye movements. Visual attention typically produces enhanced perceptual processing at the locus or object to which it is directed. Neurones in several regions of the visual cortex are modulated by attention but also respond in relation to visually guided saccadic eye movements. A central issue regarding attentive processing is what happens with the information across saccades. Specifically, how can attention be maintained on a visual object, even if its representation in retinotopically organised visual areas is drastically changed by an eye movement? In order to address this issue, we studied the relation between attention and saccades in striate cortex of monkeys trained to perform a curve-tracing task. In this task, the monkey has to segregate a target curve from a distractor curve. On some trials, a segment of a target or distractor curve appeared in the receptive field (RF) due to the stimulus onset (onset condition). On other trials, the curves were remote from the RF at stimulus onset, but after a delay, an eye movement was made that brought the RF onto a segment of the target or distractor curve (saccade condition). Responses to the target curve were enhanced relative to the responses to the distractor curve. In the onset condition, attentional modulation occurred at a latency of 138 ms after stimulus onset. In the condition where a saccade dragged the RF over a curve the latency of attentional modulation was significantly reduced, by 72 ms. Note, however, that in this condition the curve segment that falls on the RF could have been assigned to either the target or distractor curve during the fixation period before the eye movement was made. Thus, the early occurrence of attentional modulation after a saccade may result from a mechanism that remaps attended objects in retinotopic coordinates. Such a mechanism may be essential for integrating information across eye movements.