Nucleus basalis of Meynert neuronal activity during a delayed response task in monkey.

A total of 183 nucleus basalis of Meynert (NBM) neurons were recorded in a monkey performing a delayed response task. Significant changes in discharge rate were detected in 74% of the NBM cells sampled with most responses occurring in the choice (64%) or the reward (67%) epochs of the task. Neuronal responses in the cueing epoch were less common (31%) and less robust than in the choice epoch, although the animal made essentially the same arm movement in both cases. Only 14% of the task-related NBM cells had significant changes in discharge rate in the delay period, and none of these responded differentially for the two positions indicated in the preceding cueing epoch. These findings do not support a role of the NBM in the differential responses of cortical neurons in delayed response tasks, but they provide further evidence for NBM involvement in aspects of reward acquisition.