03078nas a2200313   4500008004100000022001400041245013800055210006900193260001600262490000700278520206400285653001002349653002102359653002502380653002702405653003702432653001102469653001102480653000902491653001702500653001602517653003102533653002502564653001602589100001702605700002102622700001302643856010802656       2026                        eng d  a1741-255200aMethodological optimization for eliciting robust median nerve somatosensory evoked potentials for realtime single trial applications.0 aMethodological optimization for eliciting robust median nerve so  c2026 Jan 090 v233 a<p>Single-trial measurement of median nerve somatosensory evoked potentials (SEPs) with noninvasive electroencephalography (EEG) is challenging due to low signal-to-noise ratio (SNR), limiting its use in real-time neurorehabilitation applications. We describe and evaluate methodological optimizations for eliciting reliable median nerve SEPs measurable in real time, with reduced reliance on post-processing.In twelve healthy participants, two sessions each, SEPs were assessed at three pulse widths (0.1, 0.5, 1 ms), at a low-frequency stimulation (0.5 Hz ± 10%), and at an intensity sufficient to evoke consistent and robust sensory nerve action potentials and compound muscle action potentials. The evoked potential operant conditioning system platform was used to monitor responses in real time. Feasibility was also evaluated in a participant with incomplete spinal cord injury (iSCI).SEP P50 and N70 were reliably elicited in healthy participants, and in individual with iSCI, across all tested pulse widths with minimal discomfort. N70 amplitude increased significantly with pulse width (χ2= 17.64,= 0.0001,= 0.80), while P50 amplitude remained unchanged. SNR showed a significant pulse width-dependent increase (χ2= 7.82,= 0.02,= 0.35) with improvements of 40% and 52% at 0.5 and 1 ms, respectively. N70 single-trial separability significantly improved at 1 ms (AUC of 0.83,χ2= 8.17,= 0.017), including the iSCI participant (0.84-less impaired hand, 0.79-more impaired hand). Test-retest reliability (intraclass correlation coefficient = 0.70-0.84,< 0.05) was highest at 0.5 ms, indicating more consistent N70 and P50 measurements across sessions at a longer pulse width.Robust median nerve SEPs can be measured at single trials with methodological optimizations such as a longer pulse width (0.5-1 ms), low frequency (0.5 Hz), a consistent afferent excitation guided by nerve and muscle responses, and a robust EEG acquisition system. This setup can be useful for real time SEP-based brain computer interface applications for rehabilitation.</p>10aAdult10aComputer Systems10aElectric Stimulation10aElectroencephalography10aEvoked Potentials, Somatosensory10aFemale10aHumans10aMale10aMedian Nerve10aMiddle Aged10aReproducibility of Results10aSpinal Cord Injuries10aYoung Adult1 aGupta, Disha1 aBrangaccio, Jodi1 aHill, NJ  uhttps://neurotechcenter.org/publications/2026/methodological-optimization-eliciting-robust-median-nerve02015nas a2200145   4500008004100000245008500041210006900126300001400195520145800209100002201667700002701689700002101716700002101737856011101758       2025                        eng d00aCharacterization of cutaneous reflexes elicited from saphenous nerve stimulation0 aCharacterization of cutaneous reflexes elicited from saphenous n  a2025–103 aPhantom limb pain (PLP) is a chronic neuropathic condition that affects amputees. Cutaneous reflexes (CRs), mediated by spinal interneuronal circuits, represent a potential pathway linking non-nociceptive input to nociceptive modulation that could be targeted with neuromodulatory techniques such as operant conditioning. The objective of this study was to develop and validate a novel method for eliciting CRs from proximal muscles via saphenous nerve stimulation to enable future applications in individuals with PLP. We recruited 14 healthy adults and elicited CRs in the rectus femoris muscle via transcutaneous stimulation of the saphenous nerve at multiple stimulation intensities below their pain thresholds. We evaluated the consistency and reliability of CR response latencies and magnitudes, comparing the symmetry between the bilaterally (e.g. right and left legs). We found that CRs could be reliably elicited 50-100ms post-stimulus using saphenous stimulation and that responses were reliable at stimulation intensities below pain thresholds. Furthermore, we found the CR responses were relatively symmetrical in our healthy adult population. This study is the first of its kind to show that proximal (vs distal) CRs could be consistently elicited through the saphenous nerve stimulation. These findings imply that proximal CRs may be a feasible target for neuromodulatory interventions such as operant conditioning paradigms in the future.1 aHardesty, Russell1 aRueda-Parra, Sebastian1 aWolpaw, Jonathan1 aBrangaccio, Jodi  uhttps://neurotechcenter.org/publications/2025/characterization-cutaneous-reflexes-elicited-saphenous-nerve02833nas a2200169   4500008004100000245011000041210006900151300001100220490000700231520221500238100001702453700002102470700002102491700002102512700001302533856011702546       2025                        eng d00aExtracting robust single-trial somatosensory evoked potentials for non-invasive brain computer interfaces0 aExtracting robust singletrial somatosensory evoked potentials fo  a0560040 v223 aObjective: Reliable extraction of single-trial somatosensory evoked potentials (SEPs) is essential for developing brain-computer interface (BCI) applications to support rehabilitation after brain injury. For real-time feedback, these responses must be extracted prospectively on every trial, with minimal post-processing and artifact correction. However, noninvasive SEPs elicited by electrical stimulation at recommended parameter settings (0.1–0.2 msec pulse width, stimulation at or below motor threshold, 2–5 Hz frequency) are typically small and variable, often requiring averaging across multiple trials or extensive processing. Here, we describe and evaluate ways to optimize the stimulation setup to enhance the signal-to-noise ratio (SNR) of noninvasive single-trial SEPs, enabling more reliable extraction. Approach: SEPs were recorded with scalp electroencephalography in tibial nerve stimulation in thirteen healthy people, and two people with CNS injuries. Three stimulation frequencies (lower than recommended: 0.2 Hz, 1 Hz, 2 Hz) with a pulse width longer than recommended (1 msec), at a stimulation intensity based on H-reflex and M-wave at Soleus muscle were evaluated. Detectability of single-trial SEPs relative to background noise was tested offline and in a pseudo-online analysis, followed by a real-time demonstration. Main results. SEP N70 was observed predominantly at the central scalp regions. Online decoding performance was significantly higher with Laplacian filter. Generalization performance showed an expected degradation, at all frequencies, with an average decrease of 5.9% (multivariate) and 6.5% (univariate), with an AUC score ranging from 0.78–0.90. The difference across stimulation frequencies was not significant. In individuals with injuries, AUC of 0.86 (incomplete spinal cord injury) and 0.81 (stroke) was feasible. Real-time demonstration showed SEP detection with AUC of 0.89. Significance This study describes and evaluates a system for extracting single-trial SEPs in real-time, suitable for a BCI-based operant conditioning. It enhances SNR of individual SEPs by alternate electrical stimulation parameters, dry headset, and optimized signal processing.1 aGupta, Disha1 aBrangaccio, Jodi1 aMojtabavi, Helia1 aWolpaw, Jonathan1 aHill, NJ  uhttps://neurotechcenter.org/publications/2025/extracting-robust-single-trial-somatosensory-evoked-potentials-non02929nas a2200181   4500008004100000245013500041210006900176300001100245490000700256520224100263100001702504700002102521700002102542700002202563700002402585700001702609856012102626       2025                        eng d00aFrequency dependence of cortical somatosensory evoked response to peripheral nerve stimulation with controlled afferent excitation0 aFrequency dependence of cortical somatosensory evoked response t  a0260350 v223 aObjective: H-reflex targeted neuroplasticity (HrTNP) protocols comprise a promising rehabilitation approach to improve motor function after brain or spinal injury. In this operant conditioning protocol, concurrent measurement of cortical responses, such as somatosensory evoked potentials (SEPs), would be useful for examining supraspinal involvement and neuroplasticity mechanisms. To date, this potential has not been exploited. However, the stimulation parameters used in the HrTNP protocol deviate from the classically recommended settings for SEP measurements. Most notably, it demands a much longer pulse width, higher stimulation intensity, and lower frequency than traditional SEP settings. In this paper, we report SEP measurements performed within the HrTNP stimulation parameter constraints, specifically characterizing the effect of stimulation frequency.
Approach: SEPs were acquired for tibial nerve stimulation at three stimulation frequencies (0.2, 1, and 2 Hz) in 13 subjects while maintaining the afferent volley by controlling the direct soleus muscle response via the Evoked Potential Operant Conditioning System. The amplitude and latency of the short-latency P40 and mid-latency N70 SEP components were measured at the central scalp region using non-invasive electroencephalography.
Main results: As frequency rose from 0.2 Hz, P40 amplitude and latency did not change. In contrast, N70 amplitude decreased significantly (39% decrease at 1 Hz, and 57% decrease at 2 Hz), presumably due to gating effects. N70 latency was not affected. Across all three frequencies, N70 amplitude increased significantly with stimulation intensity and correlated with M-wave amplitude.
Significance: We assess SEPs within an HrTNP protocol, focusing on P40 and N70, elicited with controlled afferent excitation at three stimulation frequencies. HrTNP conditioning protocols show promise for enhancing motor function after brain and spinal injuries. While SEPs offer valuable insights into supraspinal involvement, the stimulation parameters in HrTNP often differ from standard SEP measurement protocols. We address these deviations and provide recommendations for effectively integrating SEP assessments into HrTNP studies.


1 aGupta, Disha1 aBrangaccio, Jodi1 aMojtabavi, Helia1 aCarp, Jonathan, S1 aWolpaw, Jonathan, R1 aHill, Jeremy  uhttps://neurotechcenter.org/publications/2025/frequency-dependence-cortical-somatosensory-evoked-response-peripheral