Periodic Reporting for period 1 - DEXTSTIM (Investigating manual dexterity in healthy people and patients after stroke using multi-locus transcranial magnetic stimulation)
Reporting period: 2023-09-01 to 2025-08-31
Stroke is a leading cause of adult disability in Europe. A considerable part of this disability is attributed to upper limb motor deficit - two-thirds of stroke survivors have trouble moving one of their hands and arms. Even if strength returns, people often struggle with the precise hand movements needed for everyday actions such as buttoning a shirt or holding a cup. Such difficulties arise from a deeper problem in the brain, including the balance between excitation and inhibition across motor regions. The DEXTSTIM project set out to understand this hidden balance. Our central goal was to perform brain-behaviour mapping to uncover how the brain organizes muscle activity for skilled hand and arm use, and then to apply this knowledge to promote hand and arm recovery after stroke. By combining advanced brain-stimulation methods with physiological and behavioural assessments, the project aimed to build the scientific foundation for brain-informed motor stroke rehabilitation, in which therapy is tailored to each patient's unique brain reserve.
During the fellowship, a new non-invasive brain mapping approach was developed to measure the excitability and communication between brain areas that associate with different muscles. This method combines magnetic resonance imaging (MRI), transcranial magnetic stimulation (TMS), electroencephalography (EEG), and electromyography (EMG) to map how signals spread within the motor cortex — creating a “neurophysiological fingerprint” of dexterity. The same principles can be applied to stroke patients recovering their hand motor function. New quantitative tasks were designed to assess different aspects of the upper-limb motor deficit, including hand and arm dexterity, muscle synergies, and learned non-use of the paretic limb. The resulting framework links individual brain mapping data with individual upper limb motor behavioural profiles. The concept is now being tested in a clinical study supported by follow-up innovation funding.
DEXTSTIM advanced the field of neurorehabilitation, introducing a multimodal method that captures the brain’s excitatory-inhibitory balance across multiple muscles' cortical representations at both cortical and corticospinal levels, along with the behavioural assessment of hand dexterity. The approach links brain data directly to behavioural motor goals, which can help occupational and physical therapists better understand which muscles and movements they may prioritize during therapy. The methods and datasets created in DEXTSTIM will also support future work on precision neuromodulation and integration of brain-based assessment into digital rehabilitation systems such as individualized video games. The project’s open tools have been shared freely, ensuring transparency and reproducibility. These developments have moved the technology from early research toward clinical validation and future real-world application in neurorehabilitation centers.