Attention focus modulates afferent input to motor cortex during skilled action

Psychomotor studies have identified a key role for attention in skill performance and acquisition. However, the neural mechanisms that underpin attention's role in motor control are not well understood. The current study investigated the differential effects of focus of attention upon short-latency afferent inhibition (SAI). SAI was chosen as it is positively correlated with the amount of sensory afference reaching the cortex. SAI is also sensitive to cholinergic influence, the same neurotransmitter involved in regulating attention, and is known to interact with other intracortical networks in the motor cortex. SAI in the first dorsal interosseous muscle was assessed while two separate groups produced the same physical sequential skill represented as a series of response key colors (external focus) or response fingers (internal focus). SAI was assessed at rest, immediately preceding, one element before or two elements before an index finger response. Compared to rest, both attention focus groups demonstrated a reduction in first dorsal interosseous SAI across the three sequence elements. However, the relative magnitude of SAI was greater under an internal focus of attention as an index finger response approached. This pattern indicates an attentional enhancement of somatosensory afference when attention is directed to a bodily dimension that counters the typical movement-related suppression of SAI. The current results support contemporary theories of attention's role in motor control, where an external focus of attention promotes a cortical state that maximizes effector coordination to maximize motor outcome.