Grant: Discovery Grants Program - Individual

Somatosensory afferents contribute to the planning and adaptation of movements and postures according to the ongoing state of the body and the environment. They play a key role in motor learning by providing information about errors in the motor command and, when altered, can have a drastic impact on motor control. Although the link between sensory and motor systems is undisputable, the underlying mechanisms by which somatosensory inputs shape motor control remain unclear. The advent of non-invasive neurostimulation opened up new opportunities to study human neurophysiology and sensorimotor control. The combined use of peripheral stimulation, causing an experimentally controlled sensory inflow, with transcranial stimulation of the motor cortex highlighted complex interactions between sensory and motor networks. The repeated application of sensory stimuli can also lead to sustained plastic changes through mechanisms similar to those observed during motor learning. However, evidence from this emerging field of research remain scarce and heterogenous. The widespread use of electrical nerve stimulation, depolarizing a mixed population of motor and sensory fibers (skin, muscle, joint, tendon), might in part account for the high variability of results across studies. Being able to isolate different sub-types of sensory afferents would lead to significant advancements in our comprehension of modality-specific interactions between sensory and motor networks. The long-term goal of the present research program is to elucidate the neurophysiological underpinnings of somatosensory and motor interactions. Knowledge from my previous work showed that stimulating over different peripheral structures (nerve, muscle, tendon, skin) with devices that use different modes of energy transmission (electrical, magnetic, vibration) results in a preferential recruitment of distinct somatosensory afferents. I therefore hypothesize that these distinctive sensory inputs would interact with motor control and neural networks through separate mechanisms. Over the next five years, three short-term objectives will overall investigate how the different somatosensory inputs recruited by peripheral electrical, magnetic and vibration interact with motor cortical excitability and neural plasticity. Each objective will apply specific experimental paradigms (Objective 1 = paired-pulse; Objective 2 = paired-associative; Objective 3 = repeated stimulation) using technologies and procedures complying with the highest standards in the fields of human neurophysiology and sensorimotor control. This proposal will offer thriving opportunities for 8 new highly qualified personnel to conduct projects in a diverse, inclusive and cutting-edge research environment. Knowledge from this proposal will bridge important gaps in our understanding of key mechanisms involved in sensorimotor control.