Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Technical Medical Center, University of Twente, Enschede, the Netherlands.
PLoS Biol. 2020 Oct 13;18(10):e3000829. doi: 10.1371/journal.pbio.3000829. eCollection 2020 Oct.
Task-related activity in the ventral thalamus, a major target of basal ganglia output, is often assumed to be permitted or triggered by changes in basal ganglia activity through gating- or rebound-like mechanisms. To test those hypotheses, we sampled single-unit activity from connected basal ganglia output and thalamic nuclei (globus pallidus-internus [GPi] and ventrolateral anterior nucleus [VLa]) in monkeys performing a reaching task. Rate increases were the most common peri-movement change in both nuclei. Moreover, peri-movement changes generally began earlier in VLa than in GPi. Simultaneously recorded GPi-VLa pairs rarely showed short-time-scale spike-to-spike correlations or slow across-trials covariations, and both were equally positive and negative. Finally, spontaneous GPi bursts and pauses were both followed by small, slow reductions in VLa rate. These results appear incompatible with standard gating and rebound models. Still, gating or rebound may be possible in other physiological situations: simulations show how GPi-VLa communication can scale with GPi synchrony and GPi-to-VLa convergence, illuminating how synchrony of basal ganglia output during motor learning or in pathological conditions may render this pathway effective. Thus, in the healthy state, basal ganglia-thalamic communication during learned movement is more subtle than expected, with changes in firing rates possibly being dominated by a common external source.
腹侧丘脑是基底神经节输出的主要靶点，其活动通常被认为是通过门控或反弹样机制，随基底神经节活动的变化而允许或触发。为了检验这些假设，我们在猴子执行伸臂任务时，从相连的基底神经节输出核和丘脑核（苍白球 internus [GPi] 和腹外侧前核 [VLa]）中采样了单个单元的活动。在这两个核中，活动率增加是最常见的运动前变化。此外，运动前变化通常在 VLa 中比在 GPi 中更早开始。同时记录的 GPi-VLa 对很少显示短时间尺度的尖峰到尖峰相关性或跨试验的缓慢协变，并且两者都是正相关和负相关。最后，自发的 GPi 爆发和暂停都伴随着 VLa 率的小而缓慢的降低。这些结果似乎与标准的门控和反弹模型不兼容。尽管如此，门控或反弹在其他生理情况下仍然是可能的：模拟表明 GPi-VLa 通信如何与 GPi 同步和 GPi 到 VLa 的收敛相适应，说明了在运动学习或病理条件下基底神经节输出的同步性如何使该途径有效。因此，在健康状态下，学习运动过程中基底神经节-丘脑的通信比预期的更为微妙，可能由共同的外部源主导放电率的变化。
