Cerebellar Cortex 4-12 Hz Oscillations and Unit Phase Relation in the Awake Rat.

Maxime Lévesque,Richard Courtemanche,Hongying Gao,J M Pierre Langlois,Clément Léna,Carla Southward

doi:10.3389/fnsys.2020.475948

Abstract

Oscillations in the granule cell layer (GCL) of the cerebellar cortex have been related to behavior and could facilitate communication with the cerebral cortex. These local field potential (LFP) oscillations, strong at 4–12 Hz in the rodent cerebellar cortex during awake immobility, should also be an indicator of an underlying influence on the patterns of the cerebellar cortex neuronal firing during rest. To address this hypothesis, cerebellar cortex LFPs and simultaneous single-neuron activity were collected during LFP oscillatory periods in the GCL of awake resting rats. During these oscillatory episodes, different types of units across the GCL and Purkinje cell layers showed variable phase-relation with the oscillatory cycles. Overall, 74% of the Golgi cell firing and 54% of the Purkinje cell simple spike (SS) firing were phase-locked with the oscillations, displaying a clear phase relationship. Despite this tendency, fewer Golgi cells (50%) and Purkinje cell’s SSs (25%) showed an oscillatory firing pattern. Oscillatory phase-locked spikes for the Golgi and Purkinje cells occurred towards the peak of the LFP cycle. GCL LFP oscillations had a strong capacity to predict the timing of Golgi cell spiking activity, indicating a strong influence of this oscillatory phenomenon over the GCL. Phase-locking was not as prominent for the Purkinje cell SS firing, indicating a weaker influence over the Purkinje cell layer, yet a similar phase relation. Overall, synaptic activity underlying GCL LFP oscillations likely exert an influence on neuronal population firing patterns in the cerebellar cortex in the awake resting state and could have a preparatory neural network shaping capacity serving as a neural baseline for upcoming cerebellar operations.

Highlights

With its systematic structure, the cerebellum possesses inherent modularity supporting the flow of information (Voogd and Glickstein, 1998; Llinás et al, 2004; Ito, 2010), and its coding capacity has been the object of multiple decades of neurophysiological inquiry (Eccles et al, 1967; Ito, 2006; Heck, 2015)
LFP3 was recorded in a different plane, at a similar depth as the lesion, yet in the cerebellar cortex from the neighboring multiunit activity, likely in the anterior copula of the pyramis region
Golgi unit activity simultaneously recorded with the LFP1 oscillations showed bursts occurring in-phase with the oscillation cycles

Summary

Introduction

The cerebellum possesses inherent modularity supporting the flow of information (Voogd and Glickstein, 1998; Llinás et al, 2004; Ito, 2010), and its coding capacity has been the object of multiple decades of neurophysiological inquiry (Eccles et al, 1967; Ito, 2006; Heck, 2015). Some of the mechanisms uncovered focus on oscillatory activity: one way Oscillatory Modulation of Cerebellar Cortex Units to control the spatiotemporal flow of information across modules is through interconnected oscillating networks: these can be variably coupled to support information flow according to specific frequencies or multiple modes (Fries, 2015; Maris et al, 2016). Slower (

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Conclusion