Spike rate modulation of locus coeruleus neurons associated with visual spatial attention in monkeys

We trained two rhesus monkeys to selectively attend one of two visual stimulus locations while performing a visual orientation change detection task. Once the animal fixated, two Gabor sample stimuli appeared for 200 ms, one in each hemifield.

After a brief delay (200-300 ms), a Gabor test stimulus appeared in one of the locations. The monkey had to report whether the test stimulus had a different orientation than the sample that had appeared in that location by making a saccade to one of two colored saccade targets after the fixation spot went off. The locations of the saccade targets were interchanged randomly across trials.