Excessive theta (θ) frequency oscillation and synchronization in the basal ganglia (BG) has been reported in elderly parkinsonian patients and animal models of levodopa (L-dopa)-induced dyskinesia (LID), particularly the θ oscillation recorded during periods when L-dopa is withdrawn (the off L-dopa state). To gain insight into processes underlying this activity, we explored the relationship between primary motor cortex (M1) oscillatory activity and BG output in LID. We recorded local field potentials in the substantia nigra pars reticulata (SNr) and M1 of awake, inattentive resting rats before and after L-dopa priming in Sham control, Parkinson disease model, and LID model groups. We found that chronic L-dopa increased θ synchronization and information flow between the SNr and M1 in off L-dopa state LID rats, with a SNr-to-M1 flow directionality. Compared with the on state, θ oscillational activity (θ synchronization and information flow) during the off state were more closely associated with abnormal involuntary movements. Our findings indicate that θ oscillation in M1 may be consequent to abnormal synchronous discharges in the BG and support the notion that M1 θ oscillation may participate in the induction of dyskinesia.

据报道，老年帕金森病患者和左旋多巴 (L-dopa) 引起的运动障碍 (LID) 动物模型中基底神经节 (BG) 存在过度的 θ (θ) 频率振荡和同步，特别是在 L- 期间记录的 θ 振荡多巴被撤回（左旋多巴关闭状态）。为了深入了解这一活动的过程，我们探索了初级运动皮层 (M1) 振荡活动与 LID 中 BG 输出之间的关系。我们记录了假手术对照组、帕金森病模型和 LID 模型组中清醒、注意力不集中的静息大鼠左旋多巴启动前后黑质网状部 (SNr) 和 M1 的局部场电位。我们发现，慢性左旋多巴增加了左旋多巴关闭状态 LID 大鼠中 SNr 和 M1 之间的 θ 同步和信息流，具有 SNr 到 M1 的流动方向性。与开启状态相比，关闭状态下的θ振荡活动（θ同步和信息流）与异常不自主运动的相关性更为密切。我们的研究结果表明，M1 中的 θ 振荡可能是 BG 中异常同步放电的结果，并支持 M1 θ 振荡可能参与运动障碍诱发的观点。