Effect of desynchronized inputs on compound sensory and muscle action potentials.
Stimulation of the second (S1) or third (S2) digit elicits a median sensory potential at the wrist. Similarly, a shock applied to the median (Sm) or ulnar (Su) nerve at the wrist evokes a sensory potential of the fourth digit and a muscle potential over the thenar eminence. Hence, a concomitant application of S1 and S2 or Sm and Su with varying interstimulus intervals simulates the effect of desynchronized inputs. In 10 hands, a shift in latency on the order of 1 msec between S1 and S2 or Sm and Su caused a major reduction in sensory potential by as much as 30-40% but little change in muscle action potential. A latency difference slightly less than one-half the total duration of unit discharge maximized the phase cancellation between the two components and consequently the loss of area under the waveform.
Kimura
J
J
Division of Clinical Electrophysiology, University of Iowa Hospitals and Clinics, Iowa City 52242.
Sakimura
Y
Y
Machida
M
M
Fuchigami
Y
Y
Ishida
T
T
Claus
D
D
Kameyama
S
S
Nakazumi
Y
Y
Wang
J
J
Yamada
T
T
D000200:Action Potentials; D004568:Electrodiagnosis; D006225:Hand / Q000294:innervation*; D006801:Humans; D009132:Muscles / Q000294:innervation* / Q000502:physiology; D009431:Neural Conduction; D011930:Reaction Time; D012677:Sensation / Q000502:physiology*