Daniel Comaduran Marquez

Perinatal stroke can lead to lifelong physical disabilities, where even small improvements in motor function can increase quality of life. Rapid brain deve

Children who have severe disabilities face heightened challenges participating in life, restricting their access to essential human rights [1]. For example, children with cerebral palsy (CP) are le...

Electroencephalography (EEG) measures the summed electrical activity from pyramidal cells in the brain by using noninvasive electrodes placed on the scalp. Traditional, voltage-based measurements are done with differential amplifiers. Depending on the location of the electrodes used for the differential measurement, EEG can estimate electrical activity from radially (common or average reference) or tangentially (bipolar derivation) oriented neurons. A limitation of the bipolar derivation is that when the electrodes are too close together, the conductive solution used to improve electrode-skin impedance can short-circuit the electrodes. Magnetoencephalography (MEG) also enables measurements from tangentially oriented cells without concerns about short-circuiting the electrodes. However, MEG is a more expensive, and a less available technology. Measuring from both radial and tangential cells can improve the resolution to localize the origin of brain activity; this could be extremely useful for diagnoses and treatment of several neurological disorders. The work presented here builds on previous research that aims to record the electrical activity of the tangentially oriented cells with technology like that of EEG. The design of the device presented here has been improved from previous implementations. Characterization of the electronics, and validation in a saline phantom and with a steady state visually evoked potentials paradigm is presented along with a comparison to a voltage-based (vEEG) amplifier. The current-based (cEEG) amplifier satisfies suggested parameters for EEG amplifiers, and exhibited higher sensitivity to tangential dipoles in the phantom study. It measured brain activity using the same scalp electrodes as vEEG amplifiers with comparable performance.

Aims: The right to play is a basic human right. However, sport participation is often limited for children with complex motor disabilities. We developed a brain-computer interface (BCI)-enabled Boccia system that allows children with severe motor disabilities and communication difficulties to play independently. The purpose of this study was to partner with persons with lived experience (PWLE) to improve the BCI-Boccia system. Methods: Following the Strategy for Patient-Oriented Research framework, we engaged seven PWLE. In the first session, we gathered comments from the PWLE, which were translated into a list of required features. The software was developed using an Agile approach. The second session involved a demonstration to collect additional feedback. In the third session, two PWLE tested the system in person. Engagement was evaluated using the Public and Patient Engagement Evaluation Tool (PPEET). Results: Comments from the PWLE focused on improving the software controller and the mechanical stability of the ramp. New software controllers for coarse and fine movements were designed, and a new base was developed to enhance stability while allowing faster assembly and disassembly. The PPEET confirmed that PWLE felt their suggestions were considered and that sufficient resources were provided to support their participation. Conclusion: We demonstrate that a patient engagement strategy can inform and facilitate improvements to a BCI-enabled Boccia system. Involving diverse PWLE throughout the design cycle may improve accessibility and user adoption in disability sports. Inclusive participation likely helps ensure that improvement efforts directly address the needs of end users.

By means of biofeedback, neuromotor control can be modified. Recent biofeedback experiments have used the power of the electromyogram of one muscle in different frequency bands to control a two-dimensional cursor. However, the human body usually requires coherent activation of multiple muscles to achieve daily life tasks. Additionally, electromyography (EMG) instrumentation has remained the same for decades, and might not be the most suitable to measure coherent activations from pennated muscles according to recent experiments by von Tscharner and colleagues. In this study, we propose the development of a multichannel current-based EMG amplifier to use intermuscular coherence as the control feature of a visual biofeedback system. The system was used in a leg extension protocol to voluntarily increase intermuscular coherence between the vastii muscles. Results from ten subjects show that it is possible to increase intermuscular coherence through visual biofeedback. Such a system can have applications in endurance training and rehabilitation.

The vasti muscles stabilize the knee joint during the running movement. This requires some motor units to synchronize. Test the hypothesis that EMGs from the vasti muscles (VM and VL) are coherent in four frequency bands, one below 30 Hz, the 40 Hz (30–45 Hz), the middle band up to 120 Hz, and the high-frequency band (135–280 Hz). Because the VM during one step and the VL during another step contain common EMG signal parts the inter-step coherence at low frequencies does not disappear when the coherence is computed between the EMG_VM obtained from one step and the EMG_VL of the previous step. Twelve participants ran on a treadmill at 2.9 m/s for 15 min. EMGs were recorded from the vasti muscles using bipolar current amplifiers. Ordinary coherence was computed between the EMG_VM and EMG_VL and for the inter-step-condition. Significant coherence was observed in all frequency bands. In the mid- and high-frequency range, coherence disappears for the inter-step condition, whereas the low-frequency coherence is still present. Four frequency bands must be considered. It was proposed that coherence at low frequencies reflects cortico-muscular interactions. However, the clustering of motor unit action potentials is sufficient to generate the low-frequency coherence as well. There is a low-frequency coherence resulting from EMGs of the vasti muscles that are similar in different steps. Therefore, at least these three effects must be considered to draw conclusions from the coherence of the vasti muscles at low frequencies that occur while running.