Berta Mateu-Yus

The development of cognitive control during childhood is characterized by progressive improvements in attentional processing and response inhibition. The present study examined neural activity associated with visual attention and inhibitory control in typically developing children aged 6 to 12 years, using quantitative high-density electroencephalography (HD-EEG).A total of 172 typically developing children aged 6 to 12 years participated in the study. Participants completed a computerized Go/NoGo task while EEG activity was recorded. Behavioural performance, event-related potentials (ERPs), and time-frequency EEG features were analysed, including median frequency (MF), spectral entropy (SE), and relative power (RP) in the theta (θ) and beta1 (β1) frequency bands. Differences were observed both between task conditions and across age groups. P300 amplitude and latency decreased linearly with age across conditions. NoGo trials elicited larger P300 amplitudes and longer latencies than Go trials. Time-frequency analyses showed reductions in MF and SE with increasing age. During task performance, RP (θ) increased and RP (β1) decreased relative to the pre-stimulus baseline. These time-frequency changes were observed across all age groups but were more pronounced in older children. All time-frequency measures differentiated Go and NoGo trials, with stronger effect observed during NoGo trials. These patterns suggest that with age, children become progressively more capable of synchronizing their frequency-specific neural activity to meet the functional demands of the task. Together, these findings indicate that HD-EEG biomarkers are useful to study the maturation of large-scale coordination mechanisms and inhibitory control networks across childhood.

Functional electrical stimulation (FES) is an effective technique for restoring motor function in patients with paralysis. The early onset of muscle fatigue remains a major drawback, limiting its widespread clinical adoption. It is hypothesized that the high frequencies used in FES may be the primary factor determining muscle fatigue onset. Yet few studies have assessed the dependence of muscle fatigue on stimulation frequency. In particular, there is a need for a systematic evaluation across a continuous range of frequencies. Muscle fatigue dependence on stimulation frequency was assessed in anesthetized sheep, with the aim of modeling human musculature with physiological fidelity in the absence of potentially interfering reflexes. Following surgical muscle exposure, symmetrical 250 + 250 µ s biphasic pulse trains were delivered via hook wire intramuscular monopolar electrodes to either the tibialis cranialis or the extensor digitorum lateralis muscle, and isometric contraction forces were recorded. Eleven frequencies were assayed from 5 Hz to 100 Hz, with rest periods of over 10 min between trials. The extracted parameters included peak force, time to peak force, time to fatigue (defined as a 25% force drop), and the slope of force decline at fatigue. Additionally, muscle contraction ripple was assessed. Both muscles exhibited increasing fatigue with frequency, revealing three distinct frequency ranges. Fatigue rate was very slow below 15–20 Hz, gradually increased between ∼20–50 Hz, and raised sharply above 50–75 Hz reaching fatigue in a few seconds. Remarkably, fatigue rate only started to increase substantially at 10–20 Hz. Force fusion increased with stimulation frequency, with both muscles showing fused contractions from approximately 12 Hz. The minimal fatigue observed at frequencies corresponding to natural motor unit firing rates suggests that the high frequencies used in FES are a key driver of fatigue.

Although biomedical engineering (BME) is a profession with ethical responsibilities comparable to those in medicine, it has, until now, lacked a counterpart to the Hippocratic Oath. While professional societies have established codes of ethics for biomedical engineers, these documents lack the symbolic and ceremonial significance of an oath or pledge. By contrast, the recitation of the Hippocratic Oath, or its modern version, the “Physician’s Pledge,” serves as a powerful rite of passage for medical students, fostering a strong sense of ethical duty at the start of their professional journey. However, the content of the Hippocratic Oath includes elements specific to clinical practice and is not directly applicable to biomedical engineering. To fill this gap, we have created a “Biomedical Engineer’s Pledge,” comprising a preamble, ten promises, and a concluding statement, to inspire ethical awareness and establish a meaningful graduation tradition. Graphical abstract