Spinal cord stimulation alters the firing rate and rhythmicity of neuronal units in basal ganglia circuits. (A), Standardized neuronal firing rate response to different SCS frequencies in multiple structures of the basal ganglia circuits (neurons rank ordered according to responses). (B), The fraction of inhibitory responses increased with higher SCS frequencies. (C), Autocorrelograms of two single units in MI exemplifying beta-range rhythmic firing pattern in a parkinsonian animal (SCS OFF). (D), Autocorrelograms of the same two units showing that the rhythmic spiking is effectively interrupted by SCS. (E), The respective power spectra OFF/ON (black/red) for the units shown in C-D. Note the peak (arrow) in the beta-range during the OFF period, which disappears during the ON period. (F), Changes in power of rhythmic beta-firing plotted for all 183 units that presented significant beta oscillations either in the OFF or ON period. Colored circles represent the units with significant suppression in beta power during the ON period. Black line denotes equal power in ON and OFF conditions, thus units located to the right of the line display beta suppression.