Department of Neuroscience, Physiology, and Pharmacology, University College London, London, UK.
University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France.
Nat Neurosci. 2021 Aug;24(8):1142-1150. doi: 10.1038/s41593-021-00873-x. Epub 2021 Jun 24.
In classical theories of cerebellar cortex, high-dimensional sensorimotor representations are used to separate neuronal activity patterns, improving associative learning and motor performance. Recent experimental studies suggest that cerebellar granule cell (GrC) population activity is low-dimensional. To examine sensorimotor representations from the point of view of downstream Purkinje cell 'decoders', we used three-dimensional acousto-optic lens two-photon microscopy to record from hundreds of GrC axons. Here we show that GrC axon population activity is high dimensional and distributed with little fine-scale spatial structure during spontaneous behaviors. Moreover, distinct behavioral states are represented along orthogonal dimensions in neuronal activity space. These results suggest that the cerebellar cortex supports high-dimensional representations and segregates behavioral state-dependent computations into orthogonal subspaces, as reported in the neocortex. Our findings match the predictions of cerebellar pattern separation theories and suggest that the cerebellum and neocortex use population codes with common features, despite their vastly different circuit structures.
在经典的小脑皮层理论中，高维感觉运动表现被用来分离神经元活动模式，从而提高联想学习和运动表现。最近的实验研究表明，小脑颗粒细胞（GrC）群体活动是低维的。为了从下游浦肯野细胞“解码器”的角度研究感觉运动表现，我们使用三维声光透镜双光子显微镜记录了数百个 GrC 轴突的活动。在这里，我们发现 GrC 轴突群体活动在自发行为期间具有高维性和分布性，几乎没有精细的空间结构。此外，不同的行为状态在神经元活动空间中沿着正交维度表示。这些结果表明，小脑皮层支持高维表示，并将行为状态相关的计算分离到正交子空间中，这与新皮层中的报告一致。我们的发现与小脑模式分离理论的预测相符，表明尽管小脑和新皮层的电路结构有很大的不同，但它们都使用具有共同特征的群体代码。
