C-fibers

Let a functionalist theory of pain (whatever its details) be instantiated by a system the subassemblies of which are not such things as C-fibers and reticular systems but telephone lines and offices staffed by people.

The Chinese Room Argument Cole, David 2004

The difference of the latencies of the responses attributed to C-fibers was 1.395 seconds to go the same distance, which corresponds to a conduction velocity of 0.7 m/s.

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010

This situation will be represented in purple in figures, with the data corresponding to C-fibers in red and those corresponding to Aδ-fibers in blue;

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010

In a second step, this approach will be extended to several body territories and data ensuring the differentiation of the responses elicited by Aδ-fibers from those elicited by C-fibers will be presented.

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010

We will refer to TψA and TψC as the psychophysical thresholds of the reactions triggered by Aδ - and C-fibers, respectively.

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010

The mathematical processing of these data provides numerical values of four variables characterizing a given body territory: true thresholds and latencies of pain triggered by heat via Aδ - ( "first pain") and C-fibers ( "second pain").

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010

For example, with a heating slope of 1°C/s, it takes approximately five seconds to pass from the threshold of activation of C polymodal nociceptors to that of the Aδ polymodal nociceptors; this time period is ample to enable activation of C-fibers to trigger a reaction even before Aδ fibers have been activated.

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010

The role of C-fibers in eliciting acute pain is small, if any.

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010

The responses triggered by Aδ-fibers were favored when the territory was remote from the CNS (e.g. the foot) and the responses triggered by C-fibers were favored when the territory was close to the CNS (e.g. the forehead).

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010

In summary, the factors favoring the triggering of pain by either unmyelinated C-fibers or myelinated Aδ-fibers include the low/high rate of stimulation, the low/high base temperature of the skin and the short/long peripheral path.

PLoS ONE Alerts: New Articles Léon Plaghki et al. 2010