β oscillations in the basal ganglia have been associated with interval timing. We recorded the putaminal local field potentials (LFPs) from monkeys performing a synchronization-continuation task (SCT) and a serial reaction-time task (RTT), where the animals produced regularly and irregularly paced tapping sequences, respectively. We compared the activation profile of β oscillations between tasks and found transient bursts of β activity in both the RTT and SCT. During the RTT, β power was higher at the beginning of the task, especially when LFPs were aligned to the stimuli. During the SCT, β was higher during the internally driven continuation phase, especially for tap-aligned LFPs. Interestingly, a set of LFPs showed an initial burst of β at the beginning of the SCT, similar to the RTT, followed by a decrease in β oscillations during the synchronization phase, to finally rebound during the continuation phase. The rebound during the continuation phase of the SCT suggests that the corticostriatal circuit is involved in the control of internally driven motor sequences. In turn, the transient bursts of β activity at the beginning of both tasks suggest that the basal ganglia produce a general initiation signal that engages the motor system in different sequential behaviors.
Keywords: interval timing; putamen; rhesus monkeys; sequential behavior; β band oscillations.
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