Cyclic time course of motor excitability modulation during the observation of a cyclic hand movement

Paola Borroni, Marcella Montagna, Gabriella Cerri, Fausto Baldissera

Research output: Contribution to journalArticle

Abstract

The observation of a sinusoidal flexion-extension of the wrist was utilized to determine the continuous time course and phase relation between observed movement and its effects on the observer's motor pathways. While observing movements performed by others, the observers' cortical motor areas and spinal circuits were activated, reflecting the specific temporal and muscular pattern of the actual movement (motor resonance). H-reflexes and motor-evoked potentials (MEPs) were elicited, respectively, by electrical stimulation of the median nerve and magnetic stimulation of the appropriate cortical area, in the right forearm muscle Flexor Carpi Radialis (FCR) of subjects who were observing a 1-Hz cyclic oscillation of the right prone hand executed by a different person. Observation elicited a parallel cyclic excitability modulation of the observer's H-reflex and MEP responses with identical period as the observed movement. Modulation was phase advanced, as is muscle activation with respect to the real movement. The same results were obtained when the observed hand oscillation was executed with different frequency (1.6 Hz) and when the hands of mover and observer were supine. No motor resonance was elicited by observing the oscillation of a metal platform. The excitability modulation of MEPs simultaneously monitored in both antagonists of the observer's forearm (FCR and Extensor Carpi Radialis, ECR) was in almost perfect phase opposition, reflecting their natural reciprocal activation during the execution of a hand oscillation. These findings suggest that during observation, motor pathways are modulated subliminally reproducing with high temporal fidelity the motor commands needed to execute the observed movement.

Original languageEnglish
Pages (from-to)115-124
Number of pages10
JournalBrain Research
Volume1065
Issue number1-2
DOIs
Publication statusPublished - Dec 14 2005

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Keywords

  • Excitability modulation
  • H-reflex
  • Mirror neuron
  • Motor resonance
  • Motor-evoked potential
  • TMS

ASJC Scopus subject areas

  • Neuroscience(all)

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