00579nas a2200121   4500008004100000245015800041210006900199100001700268700001900285700002100304700001300325856011900338       2026                        eng d00aA portable closed-loop platform enabling cortical evoked potential operant conditioning: System development and validation of target intensity estimation0 aportable closedloop platform enabling cortical evoked potential 1 aGupta, Disha1 aBrangaccio, JA1 aMojtabavi, Helia1 aHill, NJ  uhttps://www.neurotechcenter.org/publications/2026/portable-closed-loop-platform-enabling-cortical-evoked-potential02320nas a2200157   4500008004100000245006500041210006500106300001600171490000800187520175900195100002501954700002101979700002302000700002402023856011502047       2025                        eng d00aBidirectional locomotion induces asymmetric limb adaptations0 aBidirectional locomotion induces asymmetric limb adaptations  a1774–17840 v1343 aHumans can acquire and maintain motor skills throughout their lives through motor learning. Motor learning and skill acquisition are essential for rehabilitation after neurological disease or injury. Adaptation, the initial stage of motor learning, involves short-term changes in motor performance in response to a new demand in the person’s environment. Repeated adaptation can improve skill performance and result in long-term skill retention. Locomotor adaptation has been extensively studied with split-belt treadmill paradigms. In this study we explored whether bidirectional walking (BDW) on a split-belt treadmill can induce short-term gait adaptations. Twelve healthy volunteers participated in our single session, starting with 2 min of forward walking (FW), followed by four 5-min blocks of BDW with a 1-min passive rest in between blocks, and ending with another 2-min block of FW. We recorded body kinematics and ground reaction forces throughout the experiment. Participants modified both temporal (interlimb phasing, double stance duration) and spatial (step length) aspects of gait to meet the mechanical demands of backward dual walking (BDW). Adaptation occurred rapidly, with bilateral reductions in step length, adjustments in stance and swing phase timing, alterations in interlimb phasing, and decreased double stance duration in the limb walking backward. Notably, only the backward-walking limb (right) exhibited persistent aftereffects upon return to FW. These results demonstrate that BDW elicits adaptations in both spatial and temporal gait parameters, with transient aftereffects consistent with short-term motor learning. To our knowledge, this is the first report characterizing such spatiotemporal adaptations during BDW.1 aHardesty, Russell, L1 aMojtabavi, Helia1 aGemoets, Darren, E1 aWolpaw, Jonathan, R  uhttps://www.neurotechcenter.org/publications/2025/bidirectional-locomotion-induces-asymmetric-limb-adaptations02837nas a2200169   4500008004100000245011000041210006900151300001100220490000700231520221500238100001702453700002102470700002102491700002102512700001302533856012102546       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://www.neurotechcenter.org/publications/2025/extracting-robust-single-trial-somatosensory-evoked-potentials-non02933nas a2200181   4500008004100000245013500041210006900176300001100245490000700256520224100263100001702504700002102521700002102542700002202563700002402585700001702609856012502626       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://www.neurotechcenter.org/publications/2025/frequency-dependence-cortical-somatosensory-evoked-response-peripheral01902nas a2200241   4500008004100000245011900041210006900160300000800229490000800237520107300245100002401318700001701342700002101359700002501380700001301405700002201418700002301440700002401463700002201487700002101509700001101530856011901541       2025                        eng d00aSoleus H-reflex size versus stimulation rate in the presence of background muscle activity: a methodological study0 aSoleus Hreflex size versus stimulation rate in the presence of b  a2150 v2433 aHoffmann reflex (HR) operant conditioning (HROC) is an important intervention for neurorehabilitation. Current HROC paradigms elicit HRs at low rates (~ 0.2 Hz), minimizing rate-dependent depression (RDD). We investigated the impact of higher stimulation rates on HR size. Fifteen healthy participants maintained low background soleus electromyographic activity (EMG) while standing. Soleus HR and M-wave recruitment curves were obtained at rates of 0.2, 1, and 2 Hz twice, from which Mmax and Hmax were calculated. Seventy-five HRs were collected for each rate at a target M-wave size (~ 10 to 20% of Mmax). HR depression was minimal at higher stimulation rates. The mean HR amplitude was reliable across the two repetitions and three rates, with high intraclass correlation coefficient (ICC) values. HROC could be performed consistently at rates up to 2 Hz with minimal HR depression. Faster rates enable more conditioning trials per session, reducing session duration and/or number, thereby potentially accelerating conditioning and reducing participant burden.1 aBrangaccio, Jodi, A1 aGupta, Disha1 aMojtabavi, Helia1 aHardesty, Russell, L1 aHill, NJ1 aCarp, Jonathan, S1 aGemoets, Darren, E1 aVaughan, Theresa, M1 aNorton, James, JS1 aPerez, Monica, A1 aothers  uhttps://www.neurotechcenter.org/publications/2025/soleus-h-reflex-size-versus-stimulation-rate-presence-background00572nas a2200157   4500008004100000022001400041245007100055210006900126260001600195300001200211490000800223100002500231700002100256700002400277856011300301       2025                        eng d  a1522-159800aSpinal reflexes: a potential target for treating hemiparetic gait.0 aSpinal reflexes a potential target for treating hemiparetic gait  c2025 Jul 01  a290-2910 v1341 aHardesty, Russell, L1 aMojtabavi, Helia1 aWolpaw, Jonathan, R  uhttps://www.neurotechcenter.org/publications/2025/spinal-reflexes-potential-target-treating-hemiparetic-gait