Neuroscience 2005 Abstract
| Presentation Number: | 399.17 |
|---|---|
| Abstract Title: | Loss of corticobulbar motor excitability during sleep in primates: preliminary findings. |
| Authors: |
Adachi, K.*1
; Rompre, S.2
; Yao, D.1
; Lavigne, G.1,2
; Sessle, B. J.1
1Physiology, Univ. of Toronto, Toronto, Canada 2PQ, 502B, 124 Edward St, M5G 1G6, |
| Primary Theme and Topics |
Sensory and Motor Systems - Muscle and Motor Unit -- Motor unit |
| Session: |
399. Motor Units Poster |
| Presentation Time: | Monday, November 14, 2005 8:00 AM-9:00 AM |
| Location: | Washington Convention Center - Hall A-C, Board # Y21 |
| Keywords: | MONKEY, MOTOR ACTIVITY |
Several sleep studies have shown that the excitability of the sensorimotor system is reduced in sleep as compared with wakefulness (W), although the mechanisms underlying the reduction of excitability across the sleep-wake cycle are still unclear. We recently reported reduction in the excitability of the jaw-opening reflex evoked by low-intensity intra-oral electrical stimulation during quiet sleep (QS) in monkeys (Lavigne et al. SfN Abst 618.15, 2003), and the aim of this study was to determine if there are also differences between W and QS in the excitability of corticobulbar projections producing rhythmic jaw movements (RJM). RJM were evoked by intracortical microstimulation (ICMS; 3s train, 150 x 0.2 ms pulses, 333 Hz) applied by a microelectrode to the monkey’s cortical masticatory area (CMA). The monkey (macaca fascicularis; 4.1 kg) was trained to sleep in a primate chair, in a sound-attenuated and dark room. Sleep was recorded and scored with standard criteria and commercial software. The physiological variables included: electoroencephalogram, eye movement, heart rate and electromyographic (EMG) activity of anterior digastric and masseter muscles, and ICMS threshold for evoked jaw movements (recorded by a motion-sensing detector). All data were obtained from 5 recording sessions. In each session, the microelectrode was left at a low-threshold ICMS site for evoking RJM, and the threshold was usually assessed at 3 different times during QS and at 3-6 times during W prior to (3 hrs) and following (1 hr) sleep. During W, ICMS induced RJM at a stable threshold (<55 µA). During QS, ICMS (up to 400 µA) failed to induce RJM although jaw-opening movements were evoked but at a threshold (150-400 µA) that was significantly (P<0.05) higher than the RJM threshold during W. Soon after the animal awoke, RJM were evoked at ICMS thresholds similar to those before sleep. These results suggest that during sleep in primates, corticobulbar trigeminal motor excitability may be depressed.
Supported by CIHR grant MT-4918
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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