Temporal delays, not underactivation of detection processes may be responsible for neglect

Abstract

We have shown that FEF lesion-induced extinction could be compensated for by changing the relative temporal onsets of two targets presented on either side of the midline. Monkeys were trained to make saccades to either of two identical visual stimuli presented with various stimulus onset asynchronies (SOA). In intact animals the targets were chosen with equal probability when they appeared simultaneously. After unilateral FEF lesions an SOA of 67–116 msec had to be introduced, with the contralesional target appearing first, to obtain equal probability choice. With a smaller target separation, averaging saccades occurred with highest frequency at similar SOAs. Our findings suggest that neglect may be attributable to more time being required in the damaged hemisphere for converting sensory information into motor responses.