Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455.
eNeuro. 2017 Apr 11;4(2). doi: 10.1523/ENEURO.0036-17.2017. eCollection 2017 Mar-Apr.
Most hypotheses of cerebellar function emphasize a role in real-time control of movements. However, the cerebellum's use of current information to adjust future movements and its involvement in sequencing, working memory, and attention argues for predicting and maintaining information over extended time windows. The present study examines the time course of Purkinje cell discharge modulation in the monkey () during manual, pseudo-random tracking. Analysis of the simple spike firing from 183 Purkinje cells during tracking reveals modulation up to 2 s before and after kinematics and position error. Modulation significance was assessed against trial shuffled firing, which decoupled simple spike activity from behavior and abolished long-range encoding while preserving data statistics. Position, velocity, and position errors have the most frequent and strongest long-range feedforward and feedback modulations, with less common, weaker long-term correlations for speed and radial error. Position, velocity, and position errors can be decoded from the population simple spike firing with considerable accuracy for even the longest predictive (-2000 to -1500 ms) and feedback (1500 to 2000 ms) epochs. Separate analysis of the simple spike firing in the initial hold period preceding tracking shows similar long-range feedforward encoding of the upcoming movement and in the final hold period feedback encoding of the just completed movement, respectively. Complex spike analysis reveals little long-term modulation with behavior. We conclude that Purkinje cell simple spike discharge includes short- and long-range representations of both upcoming and preceding behavior that could underlie cerebellar involvement in error correction, working memory, and sequencing.
大多数小脑功能的假说都强调了其在实时运动控制中的作用。然而,小脑利用当前信息来调整未来运动,以及它在序列、工作记忆和注意力中的参与,表明其在扩展的时间窗口中具有预测和保持信息的能力。本研究考察了猴子在手动、伪随机跟踪过程中浦肯野细胞放电调制的时间进程。对 183 个浦肯野细胞在跟踪过程中的简单尖峰放电进行分析,结果显示在运动学和位置误差之前和之后长达 2 秒的时间内都存在调制。通过对试验随机化放电的分析,评估了调制的显著性,这种方法将简单尖峰活动与行为解耦,同时消除了长程编码,而保留了数据统计特性。位置、速度和位置误差具有最频繁和最强的长程前馈和反馈调制,而速度和径向误差的长程相关性则较少见且较弱。即使在最长的预测(-2000 到-1500ms)和反馈(1500 到 2000ms)时段,也可以从群体简单尖峰放电中相当准确地解码位置、速度和位置误差。在跟踪前的初始保持期内对简单尖峰放电的单独分析表明,即将到来的运动具有类似的长程前馈编码,而在刚刚完成的运动的最后保持期内则具有反馈编码。复杂尖峰分析显示与行为的调制很少。我们得出结论,浦肯野细胞简单尖峰放电包括即将到来和之前行为的短期和长期表示,这可能是小脑参与错误校正、工作记忆和序列的基础。