Effect of lesions on cortical-generalized seizures in the kindled rat: Spinal transections

The convulsions which accompany cortical-generalized seizures in the kinkled rat commonly consist of three separate components: “early” clonus, “tonus,” and “late” clonus. Previous studies indicated that the first two of these can be differentially suppressed by selective brain lesions. In the present study, a series of partial and total sections of the spinal cord was carried out in an attempt to relate the various elements of the tripartite convulsion to specific spinal tracts. It was easily established that the tonic element of the convulsion could be suppressed by section of the dorsolateral cord, presumably due to interruption of the rubrospinal tract. Early and late clonus, however, survived every manipulation short of complete transection of the cord. Even contralateral hemisections placed a few millimeters apart did not diminish these elements of the cortical-generalized convulsive response. This unexpected result seems to suggest that early and late clonus depend not on direct descending connections from the brain, but rather on the activation of some sort of nonspecific neuronal pool within the cord itself.