Cerebellar control of locomotion: effects of cooling cerebellar intermediate cortex in high decerebrate and awake walking cats.

Abstract

The effects of cerebellar cooling on the locomotion of precollicular, premammilary decerebrate cats and unrestrained awake cats were examined by cinematographic analysis of the limb joint movements and simultaneous electromyographic (EMG) recording. In these 2 kinds of walking cats, temporary cooling of lobule V of the cerebellar intermediate cortex and the adjacent hemisphere induced hyperflexed locomotor movements in the ipsilateral forelimb: the maximally flexed elbow angle in the swing phase was reduced significantly (by 59%) and the duration of the swing phase was prolonged by 94% in all cats, while the duration of the stance phase was shortened by 49% in 80% of the cats. In the contralateral forelimb, the duration of the swing phase was shortened by 29% and that of the stance phase was prolonged by 14%. The alterating forelimb footfalls were changed into an asymmetric pattern, while the hindlimbs retained their symmetrical alternations. These changes affected the equilibrium of the body trunk during locomotion, as actually seen in the unrestrained awake cats. Acute destruction of the intermediate lobule V in decerebrate walking cats resulted in changes of a similar magnitude, suggesting that the cooling effects are attributable, at least largely, to this single lobule. Cerebellar signals from the intermediate lobule V contribute to the proper timing of touchdown and lift-off of the forelimbs by controlling flexor and extensor activities at their appropriate levels.