Cutaneous afferents mediating the cutaneous silent period in the upper limbs: Evidences for a role of low-threshold sensory fibres

Mariano Serrao, Leoluca Parisi, Francesco Pierelli, Paolo Rossi

Research output: Contribution to journalArticlepeer-review

Abstract

Objectives: To evaluate the contribution of the low-threshold afferents to the production of the cutaneous silent period (CSP) in the upper limbs. Methods: The CSP was studied in 10 healthy adults and 4 patients with Friedreich's ataxia. The following neurophysiological aspects were studied: (a) relationship between sensory threshold (ST), sensory action potential (SAP) amplitude and CSP parameters; (b) habituation and recovery cycle of the CSP at different stimulus intensities (2 × ST and 8 × ST); (c) pattern of responses in distal and proximal muscles at different stimulus intensities (2 × ST and 8 × ST). Results: (a) The CSP occurred at low intensities (1 × ST and 2 × ST) and increased abruptly between 3.5 × ST and 4 × ST (corresponding to the pain threshold). The SAP amplitude was saturated before CSP saturation. In the patients with Friedreich's ataxia, the CSP appeared only at higher stimulus intensities (6 × ST-8 × ST). (b) The CSP evoked at 2 × ST showed a fast habituation and slow recovery cycle whereas the opposite behaviour was found at 8 × ST. (c) Low-threshold stimuli induced an inhibitory response restricted to the distal muscles. High-intensity stimulation produced an electromyographic suppression, significantly increasing from proximal to distal muscles. Conclusions: Our findings support the notion that low-threshold afferents participate in the production of the CSP in the upper limbs. The different afferents may activate different central neural networks with separate functional significance.

Original languageEnglish
Pages (from-to)2007-2014
Number of pages8
JournalClinical Neurophysiology
Volume112
Issue number11
DOIs
Publication statusPublished - 2001

Keywords

  • Central neural networks
  • Cutaneous silent period
  • Low-threshold afferents

ASJC Scopus subject areas

  • Clinical Neurology
  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Sensory Systems
  • Physiology (medical)

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