The Firing Pattern of Dorsal Spinocerebellar Tract Neurones during Inhibition

Abstract

Abstract Dorsal spinocerebellar tract neurones adequately activated by Ia afferents from the tibialias anterior (TA), extensor digitorum longus (EDL) or flexor digitorum longus (FDL) muscles are regularly inhibited by group I afferents from the gastrocnemius‐soleus (GS) nerve. The inhibition is maintained throughout the duration of GS nerve stimulation. During inhibition the irregularity of firing may be unchanged or moderately reduced. Correspondingly the serial dependency between neighbouring intervals may be unchanged or reduced. The inhibitory input usually caused a constant reduction in firing frequency at various levels of excitatory drive or occasionally a greater reduction at higher levels of excitatory drive. The latter effect was associated with increased regularity of firing and reduced serial dependency. Comparable inhibitory effects were obtained by repetitive stimulation of the contralateral somato sensory‐cortex. It is suggested that the inhibitory effects can be accounted for by post‐synaptic inhibitory mechanisms.