Center of Functionally Integrative Neuroscience (CFIN), Aarhus University, Aarhus C 8000, Denmark
Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus C 8000, Denmark.
eNeuro. 2024 Apr 29;11(4). doi: 10.1523/ENEURO.0070-24.2024. Print 2024 Apr.
The cerebellum has the reputation of being a primitive part of the brain that mostly is involved in motor coordination and motor control. Older lesion studies and more recent electrophysiological studies have, however, indicated that it is involved in temporal perception and temporal expectation building. An outstanding question is whether this temporal expectation building cerebellar activity has functional relevance. In this study, we collected magnetoencephalographic data from 30 healthy participants performing a detection task on at-threshold stimulation that was presented at the end of a sequence of temporally regular or irregular above-threshold stimulation. We found that behavioral detection rates depended on the degree of irregularity in the sequence preceding it. We also found cerebellar responses evoked by above-threshold and at-threshold stimulation. The evoked responses to at-threshold stimulation differed significantly, depending on whether it was preceded by a regular or an irregular sequence. Finally, we found that detection performance across participants correlated significantly with the differences in cerebellar evoked responses to the at-threshold stimulation, demonstrating the functional relevance of cerebellar activity in sensory expectation building. We furthermore found evidence of thalamic involvement, as indicated by responses in the beta band (14-30 Hz) and by significant modulations of cerebello-thalamic connectivity by the regularity of the sequence and the kind of stimulation terminating the sequence. These results provide evidence that the temporal expectation building mechanism of the cerebellum, what we and others have called an internal clock, shows functional relevance by regulating behavior and performance in sensory action that requires acting and integrating evidence over precise timescales.
小脑素有大脑原始部分之称，主要参与运动协调和运动控制。然而，早期的病变研究和最近的电生理学研究表明，它也参与时间知觉和时间预期的建立。一个悬而未决的问题是，这种时间预期建立的小脑活动是否具有功能相关性。在这项研究中，我们从 30 名健康参与者那里收集了脑磁图数据，他们在阈下刺激结束时，在时间规则或不规则的阈上刺激序列之后执行检测任务。我们发现，行为检测率取决于其前导序列的不规则程度。我们还发现了由阈上和阈下刺激引起的小脑反应。阈下刺激引起的诱发电应差异显著，这取决于其前导序列是规则序列还是不规则序列。最后，我们发现，参与者的检测性能与阈下刺激引起的小脑诱发电应的差异显著相关，证明了小脑活动在感觉预期建立中的功能相关性。我们还发现了丘脑参与的证据，表现为β频段（14-30Hz）的反应，以及序列规则和终止序列的刺激类型对小脑-丘脑连接的显著调制。这些结果提供了证据，表明小脑的时间预期建立机制，即我们和其他人所称的内部时钟，通过调节需要在精确时间尺度上进行行动和整合证据的感觉动作的行为和表现，显示出功能相关性。
