NeuroN · Neurophysiological Biomarkers of Cortical Plasticity Induced by Neuromodulation

Neurophysiological Biomarkers of Cortical Plasticity Induced by Neuromodulation

The aim of the project NeuroN is to investigate the neurophysiological correlates of changes in excitability of the cortical and spinal pathways involved into ankle dorsiflexion in healthy individuals as well as in acute stroke patients. Stroke is one the major causes of death and serious long-term disability nowadays. Approximately 1.1 million people in Europe suffered a stroke each year, and ischemic stroke accounts for almost 80% of the cases. Also, as the population is constantly ageing, the incidence of stroke is expected to increase. When it is not fatal, stroke consequences can be devastating and can impact substantially the quality of life. Hemiparesis, lack of coordination, spasticity, communication and cognitive disorders are among the most common motor impairments. Among others, stroke survivors may exhibit a reduced walking performance due to a decreased range of motion of the ankle joint resulting in the so-called drop foot. Recovery of walking for post-stroke patients is mostly based on physical therapy activities which involve direct therapists’ observations and manipulation of the lower limbs (bottom-up approach). Although proven to be successful, this type of training induces high cost for the healthcare systems. Hence, many studies have tried to seek for alternative type of training by focusing on motor learning and plasticity as the key to induce a lasting brain reorganization. Brain-computer interfaces, which have been developed to control rehabilitation robots or electrical stimulation of muscles, have proven to be effective only when the artificial activation of somatosensory afferents reaches the sensory cortex during the negative phase of the movement-related cortical potential usually detected up to 1 s before the actual movement execution (or the attempted one). Such a closed-loop BCI system has proven to increase cortical excitability and thus to activate and reorganize the motor cortex areas. In NeuroN we explored the effectiveness of BCI training on acute stroke patients and we investigated the changes occurring in the cortical and spinal pathways and how the same are modified after the training. The outcomes of the research were impressive as we have highlighted how new pathways emerge as an alternative to pyramidal pathways. We suggest that these new pathways are of reticulospinal origin with oscillations around 13 Hz and that they are suppressed following the BCI training as a proof of the effectiveness of the platform in reorganizing brain areas.

Data: CORDIS, © European Union