NeuralCon · Connectivity in the neural control of muscles in stroke patients.

Connectivity in the neural control of muscles in stroke patients.

The project NeuralCon aims to overcome the existing limitations in the estimation of the coupling between muscles and provide new insights on the control of multiple muscles in healthy individuals and stroke patients. This innovative research will be based on information extracted by advanced decomposition algorithms from the concurrent neural activity of multiple muscles. Stroke is one of the most important causes of disability worldwide. After a stroke, the motor deficits of upper and lower limbs may be substantial. In recent years, the hypothesis that the coordination of multiple muscles is wired at the neural level in a synergistic way has received strong experimental evidence. In case of ischemic stroke, the synergistic patterns are highly impaired and result in abnormal co-activation patterns that are functionally limiting since they decrease the capacity to activate the muscles independently. The degree of abnormal muscle co-contraction and spasticity may restrict the efficiency of rehabilitation training. In experimental conditions, it is possible to measure the degree of synergy between muscles from the recorded electromyographic (EMG) signals. However, recent literature has shown some important limitations of the approaches based on standard surface EMG signals. Recently, surface EMG electrodes may be combined in 2D arrays covering a relatively large portion of the investigated muscle(s). High-density sEMG signals can provide important information on the characteristics of different motor units, both at the peripheral and central levels and allow overcoming the classically used techniques based on amplitude characteristics of the signal to infer the neural activation of the muscles. In fact, more advanced methods that are capable of identifying the discharge times of individual motor units are now available for HD sEMG signals. Starting from this information, it is possible to extract variables that are related to the actual synaptic input received by the motor neurons. For these reasons, the project Neuralcon addressed the characterization of the neural coupling using innovative approaches applied to pre-processed high-density EMG signals and the spike trains identified from multiple muscles during voluntary contractions. The final aim was the identification of advanced biomarkers for assessing and monitoring motor dysfunction during the rehabilitation of stroke individuals. The results of the project showed that the analysis of the high-density EMG recordings during voluntary isometric contractions in the upper and lower limbs of stroke individuals can provide important information on the synergistic control of multiple muscle groups during the rehabilitation process. It was demonstrated that markers of neural activity (spinal motor neuron) can describe the fatigability and the spasticity in these patients and provide new clinical markers of motor impairment. During the project, we committed designing innovative algorithms for the improvement of motor unit identification, tracking, and alpha motor neuron spike train processing in order to make the clinical translation of these tools a reality in the near future.

Data: CORDIS, © European Union