Functional attributes discriminating mechano-insensitive
and mechano-responsive C nociceptors in human skin
H. O. Handwerker,
Journal of Neuroscience
vol. 19, no. 22, pp. 10184-10190, Nov. 1999.
© 1999 by the Society for Neuroscience
Microneurography was used in healthy human subjects to record action
potentials from unmyelinated nerve fibers (C units) in cutaneous
fascicles of the peroneal nerve.
Activity-dependent slowing (n = 96) and transcutaneous electrical
thresholds (n = 67) were determined. Eight units were sympathetic
efferents according to their responses to sympathetic reflex
provocations. Mechano-heat-responsive C units (CMH) (n = 56) had
thresholds to von Frey hair stimulation <=90 mN (6.5 bar).
Mechano-insensitive C units (n = 32) were unresponsive to 750 mN
Twenty-six mechano-insensitive units responded to heat (CH), and the
remaining six units did not respond to physical stimuli but were
proven to be afferent by their response to intracutaneous capsaicin (CMiHi).
Mechano-insensitive units had significantly slower conduction velocity
(0.81 ± 0.03 m/sec), and CH units had higher heat thresholds
(48.0 ± 0.6°C) compared with CMH units (1.01 ± 0.01 m/sec; 40.7 ± 0.4°C).
Transcutaneous electrical thresholds were <9 mA for CMH units and
>35 mA for CH and CMiHi units. Activity-dependent slowing was much more
pronounced in mechano-insensitive than in mechano-responsive units,
without overlap. Sympathetic efferent C units showed intermediate
slowing, significantly different from CMH, and completely separate from
CH and CMiHi units. The activity-dependent slowing of conduction
provides evidence for different membrane attributes of different classes
of C fibers in humans.
Report on parameter estimation of latency shift and recovery constant of C-fiber units.
SPIE Conference paper on detection and discrimination of action potentials.
Master thesis on the implementation of the detection and discrimination algorithms.
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