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CURRENT SOURCE DENSITY CORRELATES OF CEREBELLAR GOLGI AND PURKINJE CELL RESPONSES TO TACTILE INPUT.

K Tahon, M Wijnants, E De Schutter, R Maex

University of Antwerp.

Journal of neurophysiology 105:1327-1341 (2011)

Abstract - The overall circuitry of the cerebellar cortex has been known for over a century, but the function of many synaptic connections remains poorly characterized in vivo. We used a one-dimensional multi-electrode probe to estimate the current source density (CSD) of Crus IIa in response to perioral tactile stimuli in anaesthetized rats, and to correlate current sinks and sources to changes in the spike rate of co-recorded Golgi and Purkinje cells. The punctate stimuli evoked two distinct early waves of excitation (at < 10 ms and ∼ 20 ms) associated with current sinks in the granular layer. The second wave was putatively of cortico-pontine origin and its associated sink was located higher in the granular layer than the first trigeminal sink. The distinctive patterns of granular-layer sinks correlated with the spike responses of co-recorded Golgi cells. In general, Golgi cell spike responses could be linearly reconstructed from the CSD profile. A dip in simple-spike activity of co-registered Purkinje cells correlated with a current source deep in the molecular layer, probably generated by basket cell synapses, interspersed between sparse early sinks presumably generated by synapses from granule cells. The late (> 30 ms) enhancement of simple-spike activity in Purkinje cells was characterized by the absence of simultaneous sinks in the granular layer and by the suppression of co-recorded Golgi cell activity, pointing at inhibition of Golgi cells by Purkinje axon collaterals as a likely mechanism of late Purkinje cell excitation.

PMID: 21228303 [PubMed]