Rest tremor is one of the most prominent clinical features of Parkinson’s disease (PD). Here, we hypothesized that cortico-basal ganglia (CBG) neurons tend to fire in a pattern that 34 matches PD tremor frequency, suggesting a resonance phenomenon. We recorded spiking 35 activity in the primary motor cortex (Ml) and Globus Pallidus external segment (GPe) of two 36 female non-human primates (NHPs), before and after parkinsonian state induction with 137 methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP). The NHP’s arm was passively rotated at 38 seven different frequencies surrounding and overlapping PD tremor frequency. We found 39 entrainment of the spiking activity to arm rotation and a significant sharpening of the tuning 40 curves in the MPTP state, with a peak response at frequencies that matched the frequency of PD 41 tremor. These results reveal increased sensitivity of the CBG network to tremor frequency and 42 could indicate that this network acts not only as a tremor switch but is involved in setting its 43 frequency.
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