Dynamics of neuron activity levels in the monkey striatum associated with performance of a multistage behavioral program.

The levels of activity of monkey putamen neurons were studied during multistage behavior. Two groups of neuron activity patterns were identified. One was a pattern of low activity, less than twice the background level; the other was a pattern of high activity, exceeding the background by a greater factor. Neither type of pattern was linked with defined neurons, but both were associated with particular stages in the behavior. Low-activity patterns were recorded primarily at stages associated with the warning signal and receipt of the food reward at the stages completing the task. High-activity patterns were associated with the animal performing actions in response to the conditioned stimulus and with the decision-taking stage, when performance of the actions involved selection of the right or left hand. In addition, the number of these patterns increased significantly in relation to signals indicating correct performance of the task. Key moments in the behavior were found to be associated with increases in the numbers of high-activity patterns and simultaneous decreases in the number of low-activity patterns.