Predictability of the target stimulus for sensory-guided movement modulates early somatosensory cortical potentials

Objective: To investigate the role of sensory modulation in the control of sensory-guided behaviour. Specifically, we hypothesized that early somatosensory evoked potentials (SEPs) would be facilitated during performance of continuous sensory-guided movement requiring sustained attention. Methods: Median nerve SEPs were elicited via electrical stimulation and recorded from scalp electrodes while subjects performed tasks requiring continuous sensory-motor transformations. Subjects received a predictable (rhythmic amplitude modulation) or unpredictable (random amplitude modulation) amplitude varying tactile stimulus (frequency constant at 20 Hz) delivered to the tip of the index finger either alone or with the requirement to track it by modulating the isometric grip force produced by the opposite hand. Results: Early SEP (N20-P27) amplitudes were differentially modulated during unpredictable tracking compared to sensory-motor controls. Specifically, N20 amplitudes were attenuated and P27 amplitudes were enhanced during sensory-guided tracking. Conclusions: Sustained attention to task-relevant sensory stimuli differentially modulates areas within primary somatosensory cortex (S I) during a continuous sensory-motor transformation. Significance: These data have implications for understanding the role of attention in regulating somatosensory cortices during sensory-motor behaviour. (c) 2006 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.