CENTRIFUGAL INFLUENCES ON SINGLE UNIT ACTIVITY IN SPINAL SENSORY PATHS

Publisher Website
Google Scholar
Abstract
In decerebrated, unanesthetized cats spinal sensory tracts and the dorsal horns of the gray matter were explored with a microelectrode. Units responding to natural peripheral stimuli were identified and attempts were then made to modify the activity of these units by electrical stimulation of various stations in the brain, care being taken to avoid antidromic excitation. The aim was to determine how centrifugal influences may interfere with the activity pattern of afferent units. The results indicate that postsynaptic sensory elements in the spinal cord are exposed to excitatory as well as inhibitory influences from the brain. It is argued that so-called "spontaneous" activity in postsynaptic sensory neurones is sometimes maintained by tonic cerebral outflow rather than by sensory inflow. Additional findings suggest that this cerebral outflow may in turn be affected by sensory inflow.