Figure 6. A–F, Effects of DBS frequency on neuronal oscillations quantified from power spectra of single-unit firing times in GPe (A–C) and SNr (D–F). A, D, Power spectra for healthy (A1, D1) and lesioned rats with and without stimulation at 30 Hz (A2, D2) and 130 Hz (A3, D3). Insets are zoomed views (5–15, 25–35, or 125–135 Hz) of wider frequency range (0–200 Hz). Peak centered at ∼9 Hz was present in both GPe (A2, A3) and SNr (D2, D3) in lesioned rats with no stimulation. Peak was not present in healthy condition (A1, D1), and HFS reduced these low-frequency oscillations in GPe (A3) and SNr (D3). Peaks in spectrum at the stimulation frequency increased in magnitude during DBS in both GPe (A2, A3) and SNr (D2, D3). Lines represent mean (colored) ± SE (shaded gray) (GPe: healthy, n = 91; postlesion, n = 62 and SNr: healthy, n = 70; postlesion, n = 51). B, C, E, F, Sum of spectral power over low-frequency (7–10 Hz) (B, E) and stimulation frequency (stimulation frequency ± 1 Hz) (C, F) bands in GPe (B, C) and SNr (E, F). HFS reduced low-frequency oscillations (B, E) and increased oscillatory activity at stimulation frequency (C, F) (p < 0.05, two-way repeated-measures ANOVA; Different letters indicate significant differences p < 0.05, post hoc Fisher's PLSD). Bars represent mean ± SE (GPe: healthy, n = 91; postlesion, n = 62 and SNr: healthy, n = 70; postlesion, n = 51). D, E, and F use the same figure legends as A–C. Gray boxes separate results by the neural regions analyzed.