Sensory-motor substrates of executive influence over skilled performance and learning

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Skilled behaviour is dependent upon the ability to extract and integrate sensory information into accurate movement commands. Declarative knowledge (i.e. facts and semantics) about a skill guides executive functions to select relevant sensory cues and the appropriate behaviour based upon past experience that will achieve the desired outcome. In contrast, procedural memories provide the sequential steps to achieve the desired behaviour. Although declarative and procedural processes are traditionally prescribed to distinct areas of the brain, procedural processes supporting skilled behaviours often appear to be subject to executive control. Increasing executive control can be beneficial when a well-learned skill needs to be rapidly modified (e.g. consciously interrupting typical procedure to increase muscle rigidity when walking on ice). In contrast, drawing on executive functions to support learning of skilled behaviours can slow the rate of improvement and lead to a failure to perform a well-practiced behaviour to the level expected (i.e. "choking" in athletics). However, the exact mechanisms by which executive processes shape more sub-conscious, automated procedural motor processes and the consequences for beneficial brain reorganization in support of learning (known as "neural plasticity") are unknown. Such knowledge is critical to predicting when executive control will be beneficial or detrimental to skilled behaviour and to maximizing the brain's ability to acquire new skilled behaviours. As executive functions are assigned based upon explicit strategies, one possibility is that executive functions, such as working memory, may affect procedural motor control by adjusting the afferent information allowed to flow into and be manipulated by procedural motor areas. Our recent and ongoing work uses a non-invasive method, called short-latency afferent inhibition (SAI), to identify specific populations or circuits of neurons in procedural motor areas that are sensitive to executive functioning. The current Discovery Grant will address: 1) the specific contributions of these sensory-motor brain circuits to skilled behaviour, 2) the sources and control of the information flowing into these circuits and 3) how these sensory motor circuits interact with other circuits of neurons that also play a role in governing skilled behaviour. The specific experiments proposed within each of these themes will enhance our fundamental understanding of somatosensory-motor integration at the cortical level and the role this plays in the performance and acquisition of skilled behaviour. Such knowledge is critical to continued work aimed at refining models of motor control and learning and maximize translations to practical application.