Involvement of striatum (putamen) neurons in motor and nonmotor behavior fragments in monkeys.

Putamen neuron spike activity associated with motor and nonmotor functions was studied in monkeys trained to behavioral programs consisting of a series of sequential actions. In general, each putamen neuron was activated during particular behavior fragments. The association of each individual neostriatal neuron with particular behavioral fragments was not constant. When the animal performed a different version of the same program (using different conditioned signals, right- or left-sided tasks, correct or erroneous performance), the neuron could lose its association with the animal's action and become involved in a different action to which it had previously produced no response. Thus, putamen neurons could demonstrate different functional modalities in different versions of the same actions. The use of additional versions of the given program always led to increases in the numbers of behavior fragments during which there were changes in the spike activity of the neurons of interest. This effect was significantly stronger in motor fragments of the program than in nonmotor fragments. These results show that putamen neurons do not have any defined specialization and have different functional modalities when the animal performs different versions of the same action. The nature of putamen neuron involvement in sensory-cognitive processes was more stable than in the organization of motor responses.