Electrophysiological representation of scratching CpG activity in the cerebellum.

Lourdes Martínez-Silva,Jorge N Quevedo,Gabriel Gutiérrez-Ospina,Elias Manjarrez,Yuri P Ivanenko

doi:10.1371/journal.pone.0109936

Abstract

We analyzed the electrical activity of neuronal populations in the cerebellum and the lumbar spinal cord during fictive scratching in adult decerebrate cats before and after selective sections of the Spino-Reticulo Cerebellar Pathway (SRCP) and the Ventral-Spino Cerebellar Tract (VSCT). During fictive scratching, we found a conspicuous sinusoidal electrical activity, called Sinusoidal Cerebellar Potentials (SCPs), in the cerebellar vermis, which exhibited smaller amplitude in the paravermal and hemisphere cortices. There was also a significant spino-cerebellar coherence between these SCPs and the lumbar sinusoidal cord dorsum potentials (SCDPs). However, during spontaneous activity such spino-cerebellar coherence between spontaneous potentials recorded in the same regions decreased. We found that the section of the SRCP and the VSCT did not abolish the amplitude of the SCPs, suggesting that there are additional pathways conveying information from the spinal CPG to the cerebellum. This is the first evidence that the sinusoidal activity associated to the spinal CPG circuitry for scratching has a broad representation in the cerebellum beyond the sensory representation from hindlimbs previously described. Furthermore, the SCPs represent the global electrical activity of the spinal CPG for scratching in the cerebellar cortex.

Highlights

Rhythmic motor tasks, like scratching, walking or swimming, are due to the rhythmic activity of spinal interneurons termed central pattern generators (CPG), that control the alternation between flexor and extensor motoneurons
We hypothesize that the rhythmic activity associated to the spinal CPG for scratching is expressed in the cerebellar cortex as the Sinusoidal Cerebellar Potentials (SCPs), with a defined representation mainly in the cerebellar vermis, where the Ventral-Spino Cerebellar Tract (VSCT) and the Spino-Reticulo Cerebellar Pathway (SRCP) have their main projections
We found that during scratching, the sinusoidal electrical potentials (SCDPs) recorded on the lumbar spinal cord occurs in synchrony with the sinusoidal cerebellar potentials (SCPs) recorded on the surface of the cerebellar cortex

Summary

Introduction

Like scratching, walking or swimming, are due to the rhythmic activity of spinal interneurons termed central pattern generators (CPG), that control the alternation between flexor and extensor motoneurons. While the identity of these interneurons remains incomplete, some efforts to understand their spatiotemporal activation have demonstrated that spinal field potentials recorded during CPG activity take the shape of sinusoidal waves (SCDPs; sinusoidal-like cord dorsum potentials). Several studies, employing extracellular field potentials and single unitary recordings, reinforce the possibility of rhythmic modulation on the cerebellar activity by spinal networks during rhythmic motor tasks. The second aim of our study was to examine the effects of disrupting the VSCT and the SRCP on the SCPs in the cerebellar cortex To this end, we performed selective sections of the VSCT and the SRCP at the appropriate spinal levels. These results are relevant because we characterize, for the first time. a defined representation of the CPG for scratching in the cerebellar cortex

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Conclusion