Goal-directed, serial and synchronous activation of neurons in the primate striatum

To study roles of cortico-basal ganglia loops in action planning, we examined interactions between the activities of simultaneously recorded neurons in the striatum of monkeys performing sequence motor tasks by cross-correlation analysis. Serial activation occurred between projection neurons in a motor sequence-dependent manner, and was in the direction of a neuron encoding an early event in the sequence to a neuron encoding the same event or later, but closer event to the reward. Synchronous activation occurred between pairs of interneurons. The serial activation seems to originate through the cortico-basal ganglia loops, because projection neurons are inhibitory. We propose that the task-dependent serial and synchronous activation of striate neurons may be a neural substrate for goal-directed planning through the basal ganglia.