Spontaneous and evoked electrical discharges from a central demyelinating lesion

Recordings have been made from afferent fibres shown to traverse a focal demyelinating lesion induced in the dorsal columns of the cat by the direct micro-injection of lysophosphatidyl choline. Many fibres were spontaneously active, discharging with steady frequencies between 15 and 45 impulses per second or discharging in bursts, for many hours. Small deformations (less than 1 mm) of the spinal cord at the site of the lesion both increased the level of sustained activity, and transiently induced activity in fibres previously electrically silent. The spontaneous and mechanically-induced discharges were shown to proceed both rostrally and caudally from the lesion. The relationship between the experimental observations and the spontaneous and movement-induced sensations experienced by patients with demyelinating lesions of the central nervous system is discussed.