Neuroscience 2004 Abstract
| Presentation Number: | 417.12 |
|---|---|
| Abstract Title: | The effect of mental effort on the amplitude of shoulder girdle reflexes? |
| Authors: |
Alexander, C. M.*1
; Chase, H.
; Reynolds, C.
; Harrison, P. J.
1Physiotherapy Dept, HHNT, London, United Kingdom |
| Primary Theme and Topics |
Motor Systems - Spinal Cord -- Reflexes |
| Session: |
417. Spinal Cord: Reflexes II Poster |
| Presentation Time: | Monday, October 25, 2004 11:00 AM-12:00 PM |
| Location: | San Diego Convention Center - Hall A-H, Board # Y3 |
| Keywords: | REFLEX, MODULATION, MOTOR CONTROL, SPINAL |
Group I afferents of the forearm and hand evoke facilitatory reflexes to the scapulothoracic muscles (Alexander & Harrison, 2003 Exp Br R 148: 277-282). These reflexes assist in stabilising the shoulder girdle during precise use of the hand and are facilitated when doing a complex task (Alexander & Harrison, 2003 SFN 186.7). We have now investigated whether these shoulder girdle reflexes are dependent on mental effort. Reflexes were evoked in trapezius by electrically stimulating the ulnar nerve. With the same background EMG the reflex was evoked whilst performing a task in which washers were manipulated onto pegs using forceps. This required a degree of mental effort. Subjects were filmed whilst performing the task. In eleven subjects, the reflex was measured a) while performing the task, b) while the hand was held stationary in the same position whilst holding the forceps and c) while the hand was held in this position and the subject watched the film of themselves performing the task. While doing this the subject was asked to concentrate on imagining themselves performing the task. The amplitude of the reflex was greater when doing the task (38%) and imagining doing the task (32%) than when compared with holding the hand stationary in a relaxed state of mind (p<0.02, p<0.04 respectively). Indeed, the amplitude of the reflex was not significantly different whether doing the task or imagining doing the task (p<0.6). In a further seven subjects, the effect of performing the task in the left hand on the reflex amplitude on the right side, was investigated. Performing the task in the left hand, while the right hand remained stationary increased the reflex amplitude on the right side when compared to the control (p<0.03). Taken together, these results suggest that concentration upon a task is an important factor in regulating reflexes in trapezius while performing complex tasks with the hand.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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