Comparison of the electrically evoked leg withdrawal reflex in cerebellar patients and healthy controls

Abstract

The aim of this study was to analyze the contribution of the cerebellum in the performance of the lower limb withdrawal reflexes. This has been accomplished by comparing the electrically evoked responses in cerebellar patients (CBL) with those in sex- and age-matched healthy control subjects (CTRL). The stimulus was applied to the subjects' medial plantar nerve in four blocks of ten trials each with switching the stimulus from one leg to the other after each block. Responses of the main muscle groups (tibial muscle: TA; gastrocnemius muscle: GA; rectus femoris muscle: RF; biceps femoris muscle: BI) of both legs were recorded during each stimulus. The group of CBL patients consisted of both focally lesioned patients (CBLf) and patients presenting a diffuse degenerative pathology (CBLd). (1) For the withdrawal reflex in CTRL subjects, responses were observed in distal and proximal muscles of the ipsilateral side and corresponding concomitant responses on the side contralateral to the stimulation, whereas in CBL patients responses were restricted primarily to distal muscles, particularly the TA of the ipsilateral, i.e. the stimulated, side. (2) The sequence of activation of the different distal and proximal muscles ipsilateral to the stimulation, derived from latencies and times-to-peak, was for the CTRL group: TA-GA-BI-RF. This sequence was found also in the CBLf patients on their unaffected side. However, on their affected side CBLf patients showed very early GA activation, almost simultaneously with TA and RF activations and before BI activation. RF activation before BI activation was also found in CBLd. In the latter group, GA was activated after RF but before BI with all responses typically delayed. (3) The general pattern of the electrically evoked lower limb reflex consisted of an early, excitatory F1 component and a later, excitatory F2 component of larger amplitude observed in the CTRL subjects and the CBLd patients. In contrast to this pattern CBLf patients exhibited large F1 components followed by small F2 components. (4) The characteristic differences in the withdrawal reflex responses of cerebellar patients depended on the type of the lesion, providing evidence for an important involvement of the cerebellum in the control of the performance of withdrawal reflexes.

Selective Impairment of the Cerebellar C1 Module Involved in Rat Hind Limb Control Reduces Step-Dependent Modulation of Cutaneous Reflexes

“…With respect to cerebellar involvement to voluntary movements and locomotion, we have only just begun to appreciate and pinpoint more precisely its modulatory actions (Bracha et al, 1999;Apps and Garwicz, 2005). For example, recent studies with human cerebellar patients indicated that the cerebellum is involved in the timing of withdrawal reflexes (Kolb et al, 2007). Other studies have indicated that the cerebellum is implicated in operant conditioning of the H-reflex (Chen and Wolpaw, 2005).…”

Down-regulation of cerebellar 5-HT2C receptors in pilocarpine-induced epilepsy in rats: Therapeutic role of Bacopa monnieri extract

“…Its major functions range from motor and sensory timing [8] to calibration of movements and reflexes [9,10]. Lesions in the cerebellum typically cause hypotonia, dysmetria and dyscoordination [11].…”

Contribution of the Cerebellum in Cue-Dependent Force Changes During an Isometric Precision Grip Task

“…The involvement of the cerebellum as a putative structure for associative learning of motor actions and sensory stimuli has been studied extensively in humans using the method of classical conditioning, for review see [ 1 ]. Simple avoiding reflexes have been most frequently tested as for instance the eye-blink reflex [ 2 – 5 ] or the lower limb withdrawal reflex in both reclining subjects [ 6 – 9 ] and standing subjects [ 10 – 12 ]. Avoiding reactions involving larger and more complex behaviour like a postural reaction to prevent a fall have also been studied, e.g.…”