Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

We investigated the modulation of cutaneous afferent input to the cerebral cortex involving the acquisition of (a) one target location and (b) three target locations. With 8 subjects, the foot plantar flexed about the ankle to a target which was 15 degrees beyond the occurrence of a cutaneous stimulus (cue) to the lateral border of the foot. Conditions were (1) Practice, Fixed; cue fixed in one position followed by (2) Acquired, Fixed; the cue continued to be fixed in one position and accuracy was above 70%, (3) Practice, Variable; cue randomly occurred at one of three locations followed by, (4) Acquired, Variable; the cue randomly occurred at one of three locations and accuracy is above 70%. Initial cortical SEPs as averages of 30-40 trials, were recorded at Cz', following single pulses to sural nerve at the lateral malleolus. Perceptual threshold was used to calibrate stimulus intensity. SEPs were significantly depressed during the Acquired compared to the Practice condition in the fixed and variable cued task (p > .05). Constancy was maintained in movement velocity, perceptual threshold and integrated EMGs in soleus (all p < .05). We conclude that during the practice of an externally cued task, the gain is elevated in the somatosensory path containing the essential cue for successful target acquisition.

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Poster Number PAnelson0165
Keywords: sensory gating, ankle movement, SEP, motor skill, somatosensory