Abstract
It is well established that when humans plan a saccade, spatial attention is drawn to the target location. Furthermore, stimuli that appear with abrupt onsets also attract attention. The aims of this study were to show that in the monkey attention is linked to the location of a planned saccade and to see whether a task-irrelevant stimulus with an abrupt onset can effectively draw attention away before the saccade is made. Two macaque monkeys were trained to perform a memory guided saccade task. During the delay 4 rings appeared, one of which was a Landolt ring. The animal's task was to indicate the orientation of this disciminandum. In some trials an irrelevant distracter was flashed at or opposite to the target location 100, 600 or 1100 ms before the rings appeared. Luminance thresholds were measured to identify the spatial location of attention. When the discriminandum was placed in the saccade target location, thresholds were significantly better than when it was placed away from the target location. When the distracter was placed away from the saccade target location, enhanced performance was seen at that location and not at the target location. However, between 600–1100 ms after the distracter was flashed, attention returned to the saccade target location. Thus, we have confirmed that in the macaque, as in humans, attention is automatically allocated to a saccadic target, but we have also shown that this spotlight of attention can be transiently disengaged from the target location. These data correlate well to the responses of neurons in the lateral intraparietal area (LIP) to task-irrelevant stimuli flashed while a monkey planned a saccade elsewhere. Together these data support the contention that LIP is involved in spatial attention.
Supported by: National Eye Institute.