Suppression of Cortical Spontaneous Barbiturate Spindles via Specific and Unspecific Projection Spinal Pathways

Abstract

ABSTRACT The effects of peripheral adequate stimulation on cortical barbiturate spindles were investigated after spinal lesions in lightly anesthetized cats. Certain effects can be evoked from the specific projection pathways, the dorsal columns and the spino‐cervical tract, but a generalized suppression of cortical spindles was obtained mainly via two other pathways. One of these pathways, identified as the bilateral ventral flexion reflex tract, ascends in the ventral funiculus. The other pathway ascends in the dorsolateral funiculus and consists of thin, possibly unmyelinated fibres. Both pathways could be activated by low and high threshold receptors in bilateral fields and gave a desyn‐chronization of cortical spindles outlasting the duration of stimulation. The cortical effects mediated via the specific projection spinal pathways were mainly found in somatosensory projection areas with a local abolition of spindles and increased background activity. In very light anesthesia a small and shortlasting generalized effect could sometimes be obtained.