A study of the cutaneous afferent input to substantia gelatinosa
Neuroscience 6(11): 2229-2237
Primary afferent input to substantia gelatinosa of the spinal cord was studied in the decerebrate cat. The responses of cells in the substantia gelatinosa to natural stimulation of the skin and to graded electrical stimulation of the sural nerve were compared. Responses of these neurons are not predictable from the known properties of the primary afferent input. Interactions between A-fiber and C-fiber input to substantia gelatinosa cells were studied using A-fiber polarization block and conditioning A-fiber stimulation during C-fiber activation of these cells. Whereas A-fiber have strong inhibitory effects on C-fiber input to large projection cells in the spinal cord, this is not true for substantia gelatinosa cells. The results do not support the idea of substantia geletinosa as a simple relay between primary afferent inputs and spinal cord projection systems.