Brain concussion in the rat

Brain concussion was consistently produced in male white rats by striking the head with a dowel, shot by a bow. The advantage of the bow is that measurable amounts of elastic potential energy can be stored for instantaneous release. The criterion used to recognize concussion was the demonstration of a transient loss of all the righting reflexes. The postural paralysis of the rat was preceded by a convulsion, suggesting that brain concussion results from excitation rather than from neuronal paralysis. Postconcussive effects were consistently demonstrated by weight loss and reduction in activity. Several days were required for recovery. We suggest that the excitation of the central nervous system, following the impulsive movement of the head, results from a massive, high frequency discharge of receptors fired into the upper cervical cord and brain stem over peripheral afferent pathways rather than from a force acting directly on internuncial neurons of the brain.