Tuning of Ranvier node and internode properties in myelinated axons to adjust action potential timing.

ABSTRACT: Action potential timing is fundamental to information processing; however, its determinants are not fully understood. Here we report unexpected structural specializations in the Ranvier nodes and internodes of auditory brainstem axons involved in sound localization. Myelination properties deviated significantly from the traditionally assumed structure. Axons responding best to low-frequency sounds had a larger diameter than high-frequency axons but, surprisingly, shorter internodes. Simulations predicted that this geometry helps to adjust the conduction velocity and timing of action potentials within the circuit. Electrophysiological recordings in vitro and in vivo confirmed higher conduction velocities in low-frequency axons. Moreover, internode length decreased and Ranvier node diameter

SUBMITTER: Ford MC 

PROVIDER: S-EPMC4560803 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature