Decremental conduction in a mammalian peripheral nerve

Abstract

Conduction velocities of the A‐beta, A‐delta and C‐fibers in isolated vagal nerves were measured before, during, and after the nerve was exposed to sodium‐deficient hypotonic solutions. The solution was kept at 230C. Recorded at a conduction distance of 18 mm and with the nerve in a 0.25% NaCl solution, the conduction velocity of the A‐beta component in the response was found to decrease at an average rate of 1.07 m/s per min; of the A‐delta, 0.35 m/s per min and of the C‐fibers, 0.020 m/s per min. Thus, the A‐delta component in the response would disappear in about 29 min; the C‐component, in 49 min; and the A‐beta component, in 54 min. Recorded at a distance of 36 mm, the decrease in conduction velocity of the A‐beta was 1.40 m/s per min, of the A‐delta, 0.43 m/s per min, and of the C‐fibers, 0.023 m/s per min. Thus, recorded at this conduction distance, the A‐delta would disappear in 20 min; the C‐component, in 36 min; and the A‐beta component, in 42 min. These findings indicate that when decremental conduction occurs in a mammalian peripheral nerve exposed to these solutions, the decrement is most apparent in the A‐delta component, then the C‐fiber component, and finally the A‐beta component in the nerve. Similar observations were obtained in nerves exposed to 0.5% NaCl solution except that the rate of decrement was slower.

Psychiatric disorders and pain: The recurrence of a comorbidity

“…If nociception is not the same as pain, can we explain this within the analogue – binary information system? Small and unmyelinated C fibers, as well as A-delta fibers, transmit through a decremental conduction that is quite more noticeable than among proprioceptive A-beta fibers[ 22 ]. Hence probably, the difference in the peripheral processing of thermalgesia from proprioception.…”