Proceedings of The Physiological Society

Physiology 2012 (Edinburgh) (2012) Proc Physiol Soc 27, PC254

Poster Communications

Electrophysiological mapping of cerebellar - striatal pathways

M. Loft1, S. Koutsikou1, R. Apps1

1. Physiology & Pharmacology, University of Bristol, Bristol, United Kingdom.

The cerebellum and the basal ganglia are major subcortical structures crucial for motor control, which are generally thought to have little or no direct interactions with one another. However, recent tracing studies provide an anatomical route by which the two structures could communicate [1-3]. The aim of the present study was to use electrophysiological techniques to investigate whether a functional link also exists between the cerebellum and the basal ganglia. Local field potentials (LFPs) and single units were recorded in the striatum following electrical stimulation of the cerebellar dentate nucleus (DN). Experiments were carried out in accordance with UK Animals (Scientific Procedures) Act 1986. Adult male Wistar rats (n=6) were anaesthetised with urethane (1.4mg/kg, i.p.) and maintained with supplementary doses of a ketamine and xylazine mix (25mg/kg and 2.5mg/kg respectively, i.p.). Craniotomies were performed to allow the placement of a bipolar stimulating electrode in DN and a recording electrode in the contralateral striatum. Stimulation of DN (single pulses, 0.2ms duration, current range: 18-600µA) evoked a localised field potential in the striatum with a mean onset latency of 4.4ms±0.24 s.e.m (n= 4). LFP peak-to-peak amplitude was measured across the dorsal-ventral extent of the striatum at three medial-lateral co-ordinates relative to midline. LFP amplitude was significantly larger in the dorsolateral striatum (dorsolateral vs dorsomedial striatum P<0.001, dorsolateral vs dorsocentral striatum P<0.001; Kruskal-Wallis with Dunn's post-test, n=4). In separate experiments DN stimulation evoked spike activity in individual striatal neurons with a high probability of occurrence and at a mean latency of 6.6ms±0.49 s.e.m (n=3 cells). Overall, these data reveal that a powerful, short latency pathway connects the cerebellar DN with the dorsolateral striatum in the rat, providing a substrate for rapid interactions between these two major motor control structures. Further investigations are underway to investigate the behavioural significance of this projection in awake adult Wistar rats during performance of a goal-directed operant task.

Where applicable, experiments conform with Society ethical requirements