Figure 4.

Effect of picrotoxin infusion into the VM thalamus on LFP oscillations in the MCx and SNpr of the dopamine cell-lesioned hemisphere during treadmill walking. A–C, Wavelet-based scalograms of LFP spectral power (left) in the MCx (A) and SNpr (C) and the MCx–SNpr FFT-based coherence (B). Recordings were made during baseline treadmill walking and after 10 min, 30 min, and up to 2 h after infusion of picrotoxin into the VM of the lesioned hemisphere (n = 7, 50 ng/0.5 μl). Bar graphs (middle) show MCx and SNpr LFP total normalized power and MCx–SNpr coherence (mean ± SEM) before and after picrotoxin infusion. The plots and scalograms indicate that infusion of picrotoxin into VM significantly reduces cortical and SNpr 30–36 Hz range LFP power and their coherence in the lesioned hemisphere (p < 0.05). LFP power and MCx–SNpr coherence show recovery to baseline levels within 1 h after picrotoxin infusion. Plots in the right panel represent averaged power spectra and MCx–SNpr coherence before and after picrotoxin infusion. D, E, Bar graphs representing step count ratios for the inner to outer hind limbs during ipsiversive (gray bars) and contraversive (green bars) walking before and after infusion of picrotoxin (D) or saline (E) into the VM. Infusion of picrotoxin significantly improved contraversive walking in the hemiparkinsonian rats within 30 min after treatment, as reflected by increases in contraversive step ratios at 10 and 30 min (p < 0.001). Saline injected into the left VM did not affect LFP activity in the MCx and SNpr (data not shown), nor did it significantly alter treadmill walking during the same time points (E). *Significant difference between the ratio of steps in contraversive relative to ipsiversive walking. †Significant difference from baseline.