Differences between the time constant of sensory and motor peripheral nerve fibers: Further studies and considerations

Marcela Panizza, Jan Nilsson, Bradley J. Roth, Stephen E. Grill, Mehmet Demirci, Mark Hallett

Research output: Contribution to journalArticlepeer-review


Using a method of latent addition, we previously demonstrated that sensory fibers had time constants that were about three times longer than those of motor fibers. The aim of the present work was to confirm this difference by determining the time constants for single sensory axons by using microneurography and for single motor axons by recording single motor units with bipolar concentric needle electrodes. To determine the influence of the conditioning pulse on the neural time constant, we used both depolarizing and hyperpolarizing conditioning pulses. When hyperpolarizing conditioning pulses at comparable intensity were applied, the tendency was to find shorter time constants than when depolarizing pulses were applied, although still with the motor time constant being slightly shorter. Although the absolute values varied with the different methods, the sensory time constant was generally three times the motor time constant for depolarizing conditioning stimuli, whereas for hyperpolarizing conditioning stimuli the difference dropped to about one and a half. These characteristics improve understanding of the behavior of sensory and motor axons, and, in particular, explain the differential excitability. Determination of neural time constants might prove valuable for clinical use.

Original languageEnglish
Pages (from-to)48-54
Number of pages7
JournalMuscle and Nerve
Issue number1
Publication statusPublished - 1998


  • Magnetic stimulation
  • Motor fibers
  • Neural time constant
  • Sensory fibers
  • Single axons

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


Dive into the research topics of 'Differences between the time constant of sensory and motor peripheral nerve fibers: Further studies and considerations'. Together they form a unique fingerprint.

Cite this