DeMOTUS: Decoding the Exact and Representative Motor Output of The Human Spinal Cord

• Applicant: Professor Alessandro del Vecchio, Ph.D.
• Subject Area: Human Cognitive and Systems Neuroscience ; Anatomy and Physiology ; Clinical Neurology; Neurosurgery and Neuroradiology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 523352235

Understanding how the central nervous system controls human movement requires precise and representative identification of the neural cells that ultimately generate muscle force: the motor units. The motor unit is the final common pathway of movement and consists of an individual spinal motor neuron and a group of muscle fibers innervated by its axon. Movement is generated by action potentials travelling from the brain, spinal cord, and afferent inputs with the goal to trigger an action potential at the spinal motor neuron level. Therefore, the recording of motor unit activity enables a direct observation of the final code of movement that generates muscle force. Because of the one-to-one associations between motor neuron and muscle fibers, spinal motor neurons are the only neural cells that can be accessed in humans with minimally invasive methods. Many questions in movement neuroscience and neurorehabilitation remain unanswered because of the lack of methods that enable the identification of populations of individual motor neurons during natural movements. In DeMOTUS we aim to revolutionize the way we study human movement by developing new sensing methods, bioinspired technologies that include biomimetic tendon-driven hand models, digital representations of these bionic system as musculoskeletal models, and a new electromyographic processing pipeline. With the use of new sensing methods that include a new 64 intramuscular electromyographic sensor array specifically studied for the intrinsic hand muscles, we aim to discover how the central nervous system controls most, if not all, the motor units during synergistic hand movements. By recording hundreds of synergistic motor units and closing the loop through motor unit real-time feedback, we aim to develop a closed-loop intervention that will allow the separation of the so-called invariant muscle-synergies. Because the motor cortex possesses a large number of motor dimensions and in humans and non-human primates there are strong one-to-one connections with spinal motor neurons, we hypothesise that with appropriate neurofeedback at the spinal motor neuron level humans can learn to selectively activate specific pools of motor units that share common and/or independent synaptic inputs. In a second stage, DeMOTUS will connect the basic scientific neurodiscoveries to humans with paralyses. The methods and design of the systems in this project will ultimately impact the life of individuals with stroke and spinal cord injury (SCI). We have already strong preliminary evidence that most individuals with stroke and SCI have large number of spared motor neurons below the level of the lesion. Therefore, all the developments and experimental results in DeMOTUS will not only be useful for basic neuroscience but also to apply this technology in patients with neural lesions for promoting neurorehabilitation and restoration of motor function.

• DFG Programme: Independent Junior Research Groups