CCN Forum - Motor cortex circuits under cognitive influence: Substrates for explicit control over implicit processes

Skilled motor performance arises from the optimal prescription of declarative and procedural knowledge. While generally beneficial to skilled performance and acquisition, excessive use of explicit strategies is known to produce unexpected decrements in skilled performance. The decrease in skilled performance is hypothesized to result from explicit bootstrapping of implicit movement kinematics and kinetics. However, the neural basis of such explicit-implicit interactions is not well understood. We have recently used transcranial magnetic stimulation to identify two different brain circuits in motor cortex by which attention and working memory can shape the output from the motor cortex to the muscles. A verbal working memory sensitive network appears to regulate somatosensory input to motor cortex for the purposes of action selection. An attention-sensitive network appears to regulate somatosensory input to motor cortex for modulation of the selected action. The attention-sensitive motor network appears to overlap with cerebellar circuits that control sensory projections to motor cortex for online motor correction/learning. Further, the attention-sensitive network appears to be an important predictor of neuroplastic potential in motor cortex following post-stroke.