Delayed alternation performance and unit activity of the caudate head and medial orbitofrontal gyrus in the monkey

It was concluded that in the delayed alternation lever- Pressing performance the caudate units, together with the prefrontal cortical E units, were concerned with the initiation of lever-pressing and that in simple alternations without delay, they are also concerned with initiation of voluntary lever-presseding.

Abstract

Single unit activity was recorded from the rostral portion of the head and body of the caudate nucleus and from the posterior surfaces of the medial orbitofrontal gyrus during delayed and simple alternation lever-pressing performances in 12 macaque monkeys. Activity of 14 caudate units was correlated with the delayed task performance. These units discharged, on average, 200 msec before the onset of EMG activity of the upper arm. These units were also activated at a similar time before the onset of EMG activity, when monkeys pressed two levers alternately. No units were found which were active during the delay period. Seven orbitofrontal units either increased or decreased their rate of discharge during and after juice delivery (lever-pressing) in the delayed task, as well as in the simple task. It was concluded that in the delayed alternation lever-pressing performance the caudate units, together with the prefrontal cortical E units, were concerned with the initiation of lever-pressing and that in simple alternation lever-pressing without delay, they are also concerned with initiation of voluntary lever-pressing.