Origin and properties of spinal cord field potentials.
Electrical or natural stimulation of cutaneous, muscle, or visceral nerves evokes a field potential in the spinal cord; the field potential elicited by each type of afferent fiber differs in wave form. Cutaneous nerve-evoked spinal cord field potentials consist of a triphasic spike, one to three negative waves, and a slow positive wave. Muscle nerve-evoked spinal cord field potentials are composed of a triphasic spike, a slow positive wave, and one to three negative waves with different relative latencies and durations than the negative waves evoked by cutaneous nerves. Visceral nerve-evoked potentials in the spinal cord comprise only a single negative wave and a slow positive wave. The triphasic spike is a compound action potential propagating through the large primary afferent fibers; the negative waves are generated by dorsal horn interneurons; the positive wave is a reflection of primary afferent depolarization. A knowledge of the origin and properties of spinal cord field potentials has practical usefulness for both the experimental neurophysiologist and the clinician.
D004568:Electrodiagnosis / Q000379:methods; D005071:Evoked Potentials / Q000187:drug effects; D006801:Humans; D009132:Muscles / Q000294:innervation; D009431:Neural Conduction; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis; D011930:Reaction Time / Q000502:physiology; D012032:Refractory Period, Electrophysiological; D012867:Skin / Q000294:innervation; D013116:Spinal Cord / Q000502:physiology*; D013118:Spinal Cord Diseases / Q000175:diagnosis; D013127:Spinal Nerves / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology