Afferent input from distal forelimb nerves to branching spinoreticular-spinocerebellar neurones in the cat

Patterns of afferent connections from receptors of the distal forelimb were investigated in neurones located in C6-C7 segments of the spinal cord with branching axons projecting to the lateral reticular nucleus and the cerebellum. Experiments were made on five adult cats under alpha-chloralose anaesthesia. After antidromic identification, EPSPs and IPSPs were recorded from 22 neurones following stimulation of deep radial, superficial radial, median and ulnar nerves. Both excitatory and inhibitory effects were found in the majority of the cells, however, in 2 cases no synaptic actions were recorded. EPSPs were evoked from group I or II muscle, or cutaneous afferents - mostly monosynaptically. IPSPs from muscle, cutaneous or flexor reflex afferents were mostly polysynaptic. Seven various types of convergence were established in the cells investigated. Significance of parallel transmission of integrated information from various receptors of the distal forelimb to the reticular formation and cerebellum is discussed.