Identification of spinal cord pathways responsible for the peroneal-evoked response in the dog.

The question of whether the dorsal columns were primarily responsible for the conduction of the peroneal-evoked cortical somatosensory response was studied by making staged scalpel transections of the spinal cord at T6 in the anesthetized dog. Control evoked potentials were followed by sequential lesioning of the spinal cord, followed by 30 minutes of evaluation to determine the effect of the lesion. Although slight shifts in latency may have occurred following a particular cut, these were usually transient and recovered to control values, regardless of the order in which various quadrants were sectioned. To alter the peroneal-evoked cortical potential in the dog, at least three quadrants of the spinal cord must be damaged to cause consistent increases in latency or loss of potentials. These findings agree with other investigators' observations in the cat, monkey and human.