Humans possess a remarkable ability to control multiple muscles in the upper extremities, enabling a wide range of complex movements. Given the large number of muscles involved in arm and shoulder motion, each with distinct anatomical and mechanical properties, movement control is believed to rely on the modulation of correlated activity between motoneuron pools. This coordination reduces the complexity of motor control, allowing for efficient movement execution.
In neuromuscular disorders, such as those affecting chronic stroke survivors or individuals recovering from breast cancer treatments, upper limb movement coordination is often impaired. These deficits may stem from the nervous system's reduced ability to restore the original connectivity between motoneuron pools. Therefore, understanding the neural mechanisms underlying coordinated muscle activity could provide valuable insights into the role of synaptic synchronization in movement generation.
Recent technological advancements have enabled significant progress in this field. Non-invasive multichannel surface electromyography combined with decomposition algorithms can now identify individual motor unit discharge patterns. This approach provides a direct and reliable measure of the correlated activity between motoneuron pools. Furthermore, emerging evidence demonstrates that non-invasive stimulation techniques, such as transcranial magnetic stimulation and sensory electrical stimulation, can effectively modulate excitatory and inhibitory synaptic inputs to motoneuron pools. These breakthroughs suggest new strategies for promoting plasticity in motoneuron connectivity, opening possibilities for improving neurorehabilitation protocols in individuals with motor disorders.
The INcEPTION has three interlinked research objectives (ROs). The RO1 seeks to reliably quantify the correlated activity between motoneuron pools during voluntary tasks involving the shoulder and arm across multiple degrees of freedom in healthy individuals. The RO2 aims to develop innovative methods for inducing reorganization of motoneuron connectivity in the main arm and shoulder muscles, using magnetic and electrical stimulation of cortical and sensory pathways. Finally, the RO3 aims to integrate findings from RO1 and RO2 into a novel framework for estimating and modulating neural activity patterns in the arm and shoulder muscles of individuals with upper limb disabilities.
