Load- and cadence-dependent modulation of somatosensory evoked potentials and Soleus H-reflexes during active leg pedaling in humans

Masanori Sakamoto, Tsuyoshi Nakajima, Toshiaki Wasaka, Tetsuo Kida, Hiroki Nakata, Takashi Endoh, Yoshiaki Nishihira, Tomoyoshi Komiyama

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Modulation of transmission in group I muscle afferent pathways to the somatosensory cortex and those to the α-motoneuron were investigated during active leg pedaling. Cerebral somatosensory evoked potentials (SEPs) and Soleus (Sol) H-reflexes following posterior tibial nerve stimulation were recorded at four different pedaling phases. The subjects were asked to perform pedaling at three different cadences (30, 45 and 60 rpm with 0.5 kp, cadence task; C-task) and with three different workloads (at 45 rpm with 0.0, 0.5 and 1.0 kp, load task; L-task). In both C- and L-tasks, Sol H-reflexes were modulated in a phase-dependent manner, showing an increase in the power phase and a decrease in the recovery phase. In contrast, the early SEP (P30-N40) components were modulated in a phase-dependent manner when the cadence and load were low. When focusing on the power phases, significant cadence- and load-dependent modulations of the P30-N40 were found, and inversely graded with the cadence and load. The H-reflex was found to be significantly decreased at the highest cadence, i.e., cadence-dependent modulation. In contrast, the H-reflex during the L-task was found to be proportional to the load. The correlation analysis between the size of H-reflex and the amount of background (BG) electromyographic (EMG) activity demonstrated that the H-reflex in the power phase did not depend on the BG EMG in either C- or L-task. These findings suggested that transmission of muscle afferents along the ascending pathways to the cerebral cortex and the spinal cord is independently controlled in accordance with the biomechanical constraints of active pedaling.

Original languageEnglish
Pages (from-to)272-285
Number of pages14
JournalBrain Research
Volume1029
Issue number2
DOIs
Publication statusPublished - 2004 Dec 17

Keywords

  • Active pedaling
  • H-reflex
  • Load- and cadence-dependent modulation
  • Phase-dependent modulation
  • Somatosensory evoked potential

ASJC Scopus subject areas

  • Neuroscience(all)

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    Sakamoto, M., Nakajima, T., Wasaka, T., Kida, T., Nakata, H., Endoh, T., Nishihira, Y., & Komiyama, T. (2004). Load- and cadence-dependent modulation of somatosensory evoked potentials and Soleus H-reflexes during active leg pedaling in humans. Brain Research, 1029(2), 272-285. https://doi.org/10.1016/j.brainres.2004.09.054