Effect of motion imagery to counter rest-induced suppression of F-wave as a measure of anterior horn cell excitability

• Published in: Clinical neurophysiology Vol. 119; no. 6; pp. 1346 - 1352
• Main Authors: Taniguchi, S., Kimura, J., Yamada, T., Ichikawa, H., Hara, M., Fujisawa, R., Shimizu, H., Tani, T.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.06.2008; Elsevier Science
• Subjects: Adult; Analysis of Variance; Anterior horn cell; Anterior Horn Cells - physiology; Biological and medical sciences; Electric Stimulation - methods; Electrodiagnosis. Electric activity recording; Evoked Potentials, Motor - physiology; Exercise - physiology; F-wave; Female; Fundamental and applied biological sciences. Psychology; General aspects. Models. Methods; Humans; Imagery (Psychotherapy); Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Motion; Motion imagery; Motor Cortex - physiology; Motor neuron excitability; Muscle, Skeletal - innervation; Muscle, Skeletal - physiology; Muscle, Skeletal - radiation effects; Nervous system; Neural Inhibition - physiology; Neural Inhibition - radiation effects; Neurology; Reaction Time - physiology; Relaxation; Vertebrates: nervous system and sense organs; Volitional relaxation; Motor neuron excitability; Volitional relaxation; F-wave; Motion imagery; Anterior horn cell; Human; Mental imagery; Motion; Suppression; Excitability; Immobilization; Recovery; Relaxation; Rest; Median nerve; Abductor pollicis brevis muscle; A wave; F wave
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/j.clinph.2007.11.179

To test if motor imagery prevents the rest-induced suppression of anterior horn cell excitability. Ten healthy subjects underwent two separate experiments, each consisting of stimulating the median nerve 100 times and recording F-waves from abductor pollicis brevis (APB) in three consecutive sessions: (1) after muscle exercise to standardize the baseline, (2) after immobilization of APB for 3 h and (3) after muscle exercise to check recovery. We instructed the subject to volitionally relax APB in experiment 1 (relaxation task), and to periodically simulate thumb abduction without actual movement in experiment 2 (imagery task). F-wave persistence and amplitude declined after relaxation task and recovered quickly after exercise, but changed little with imagery task. F-wave latencies showed no change when analyzed individually. The frequency distribution of collective F-waves recorded from all subjects remained the same after relaxation task, but showed a shift toward longer latencies after imagery task. Mental imagery without overt motor output suffices to counter the effect of sustained volitional muscle relaxation, which would, otherwise, cause a reversible reduction in anterior horn cell excitability. This finding documents the importance of central drive for spinal excitability, which affects F-wave studies of a paretic muscle.