Mechanoreceptive afferents exhibit functionally-specific activity dependent changes in conduction velocity.
Impulse activity in axons generates aftereffects on membrane excitability that can alter the conduction velocity of subsequently conducted impulses. We used a computerized stimulus pattern (a 1 Hz stimulus period followed by a period of repeated short bursts at 200 Hz) to assess in vivo activity-dependent changes in conduction latency of functionally identified rat cutaneous afferents conducting in the A beta range. Several different parameters of activity dependence were measured: burst supernormality, the average increase in conduction latency following conditioning with a single preceding impulse during high frequency burst stimulation; burst subnormality, the average latency increase during each burst; depression, a long-term increase in latency caused by the high frequency stimulation. The data show that different mechanosensitive A beta afferents with overlapping resting conduction velocities exhibit activity-dependent changes in conduction latency that are characteristic of their particular functions.
Waikar
S S
SS
Department of Anesthesia Research Laboratories, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Thalhammer
J G
JG
Raymond
S A
SA
Huang
J H
JH
Chang
D S
DS
Strichartz
G R
GR
D000818:Animals; D001369:Axons / Q000502:physiology; D004558:Electric Stimulation; D008465:Mechanoreceptors / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D051381:Rats; D012584:Sciatic Nerve / Q000166:cytology / Q000502:physiology; D012867:Skin / Q000294:innervation