Putamen neurons process both sensory and motor information during a complex task.

The putamen has classically been considered to be primarily a motor structure. It is involved in a broad range of roles and its neurons have been postulated to function as pattern classifiers of behaviourally significant events. However, its specific role in motor and sensory processing is still unclear. For the purpose of better categorizing putamen neurons, we trained two rhesus monkeys to perform multisensory operant tasks by using complex stimuli such as short videoclips. Trials involved image or soundtrack or both. Some stimuli required a motor response associated to reward, whereas others did not require response and produced no reward. We found that neurons in the putamen showed pure visual responses, action-related activity, and reward responses. Insofar as action-related activity, preparation of movement, movement execution, and withholding of movement involved three different putamen neuron populations. Moreover, our data suggest an involvement of putamen neurons in processing primary rewards and visual events in a complex task, which may contribute to reinforcement learning through stimulus-reward association.