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Diurnal H-reflex variation in mice.
Jonathan S Carp1, Ann M Tennissen, Xiang Yang Chen
1Laboratory of Nervous System Disorders, Wadsworth Center, New York State Department of Health, State University of New York, Albany, NY 12201-0509, USA. carpj@wadsworth.org
Experimental Brain Research
|September 10, 2005
Summary
Mice show daily changes in spinal reflexes, like the H-reflex (HR). The H-reflex was typically larger in the dark than in the light, suggesting daily variations in nervous system control.
Area of Science:
- Neuroscience
- Physiology
Background:
- Complex motor behaviors in mice show diurnal variation.
- Little is known about daily changes in simple, spinally-mediated reflexes.
Purpose of the Study:
- To investigate diurnal variation in the H-reflex (HR) in mice.
- To determine if supraspinal control of spinal reflexes varies daily.
Main Methods:
- Implanted electrodes in mice for tibial nerve stimulation and muscle recording (EMG).
- Recorded H-reflex (HR) and ongoing EMG activity continuously for 10 days.
- Analyzed HR amplitude variations in relation to light/dark cycles and ongoing activity.
Main Results:
- H-reflex (HR) amplitude exhibited significant diurnal variation in mice.
- HRs were generally larger during the dark phase compared to the light phase.
- This variation persisted even after controlling for ongoing muscle activity and stimulus intensity.
Conclusions:
- The excitability of the mouse H-reflex pathway shows daily fluctuations.
- Supraspinal control of spinal reflex pathways exhibits species-specific diurnal patterns.
- Temporal variations in spinal reflex activity should be considered in research and clinical settings.