@article {4609,
	title = {Methodological optimization for eliciting robust median nerve somatosensory evoked potentials for realtime single trial applications.},
	journal = {J Neural Eng},
	volume = {23},
	year = {2026},
	month = {2026 Jan 09},
	abstract = {<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 {\textpm} 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>},
	keywords = {Adult, Computer Systems, Electric Stimulation, Electroencephalography, Evoked Potentials, Somatosensory, Female, Humans, Male, Median Nerve, Middle Aged, Reproducibility of Results, Spinal Cord Injuries, Young Adult},
	issn = {1741-2552},
	doi = {10.1088/1741-2552/ae30ac},
	author = {Gupta, Disha and Brangaccio, Jodi and Hill, NJ}
}
@article {4610,
	title = {A portable cortical evoked potential operant conditioning system (C-EPOCS): System development},
	journal = {bioRxiv},
	year = {2026},
	pages = {2026{\textendash}01},
	abstract = {This study presents customizations and evaluations aimed at adapting the Cortical-Evoked Potential Operant Conditioning System (C-EPOCS) into a portable, user-friendly platform for real-time neurofeedback applications. A primary goal was to simplify the component-heavy setup by integrating electroencephalography (EEG) and electromyography (EMG) data acquisition into a single system-while still supporting cortical and muscle response assessment and real-time feedback. One key limitation of portable biosignal acquisition systems is their typically lower sampling rates (e.g., 300-600 Hz) compared to high-resolution systems (e.g., 3200 Hz), which are commonly used for detecting transient responses such as the H-reflex and M-wave. In a CEPOCS setup, these responses are useful for determining the target stimulation intensity and minimizing inter-session variability in effective afferent excitation. We evaluated whether lower-resolution EMG signals could still support the generation of H-reflex and M-wave recruitment curves for determining target stimulation intensity. Results showed that while EMG sampled at ~600 Hz and ~300 Hz produced greater dispersion in recruitment curve data, particularly at 300 Hz, they still yielded comparable estimates for stimulation intensities that elicit Hmax and Mthreshold, the key parameters for C-EPOCS. Additionally, we demonstrate the feasibility of using an automated response delineation algorithm under these conditions. Despite reduced signal clarity, the algorithm reliably identifies M-wave and H-reflex responses in real time. Overall, this study demonstrates the feasibility of a portable C-EPOCS system capable of providing immediate feedback based on both EMG and EEG signals. It also offers practical recommendations for selecting acquisition hardware to support reliable signal quality, real-time processing, and portability.},
	author = {Gupta, Disha and Brangaccio, Jodi and Mojtabavi, Helia and Hill, NJ}
}
@article {4608,
	title = {Extracting robust single-trial somatosensory evoked potentials for non-invasive brain computer interfaces},
	journal = {Journal of Neural Engineering},
	volume = {22},
	year = {2025},
	pages = {056004},
	abstract = {Objective: 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{\textendash}0.2 msec pulse width, stimulation at or below motor threshold, 2{\textendash}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{\textendash}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.},
	author = {Gupta, Disha and Brangaccio, Jodi and Mojtabavi, Helia and Wolpaw, Jonathan and Hill, NJ}
}
@article {4606,
	title = {Soleus H-reflex size versus stimulation rate in the presence of background muscle activity: a methodological study},
	journal = {Experimental brain research},
	volume = {243},
	year = {2025},
	pages = {215},
	abstract = {Hoffmann 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.},
	author = {Brangaccio, Jodi A and Gupta, Disha and Mojtabavi, Helia and Hardesty, Russell L and Hill, NJ and Carp, Jonathan S and Gemoets, Darren E and Vaughan, Theresa M and Norton, James JS and Perez, Monica A and others}
}
@article {4110,
	title = {Effects of Sensorimotor Rhythm Modulation on the Human Flexor Carpi Radialis H-Reflex},
	journal = {Frontiers in Neuroscience},
	volume = {12},
	year = {2018},
	month = {07/2018},
	chapter = {505},
	abstract = {People can learn over training sessions to increase or decrease sensorimotor rhythms (SMRs) in the electroencephalogram (EEG). Activity-dependent brain plasticity is thought to guide spinal plasticity during motor skill learning; thus, SMR training may affect spinal reflexes and thereby influence motor control. To test this hypothesis, we investigated the effects of learned mu (8{\textendash}13 Hz) SMR modulation on the flexor carpi radialis (FCR) H-reflex in 6 subjects with no known neurological conditions and 2 subjects with chronic incomplete spinal cord injury (SCI). All subjects had learned and practiced over more than 10 < 30-min training sessions to increase (SMR-up trials) and decrease (SMR-down trials) mu-rhythm amplitude over the hand/arm area of left sensorimotor cortex with >=80\% accuracy. Right FCR H-reflexes were elicited at random times during SMR-up and SMR-down trials, and in between trials. SMR modulation affected H-reflex size. In all the neurologically normal subjects, the H-reflex was significantly larger [116\% {\textpm} 6 (mean {\textpm} SE)] during SMR-up trials than between trials, and significantly smaller (92\% {\textpm} 1) during SMR-down trials than between trials (p < 0.05 for both, paired t-test). One subject with SCI showed similar H-reflex size dependence (high for SMR-up trials, low for SMR-down trials): the other subject with SCI showed no dependence. These results support the hypothesis that SMR modulation has predictable effects on spinal reflex excitability in people who are neurologically normal; they also suggest that it might be used to enhance therapies that seek to improve functional recovery in some individuals with SCI or other CNS disorders.

},
	keywords = {brain-computer interface (BC), EEG mu-rhythm, H-Reflex, Spinal Cord Injuries, task-dependent adaptation},
	issn = {1662-453X},
	doi = {10.3389/fnins.2018.00505},
	url = {https://www.frontiersin.org/article/10.3389/fnins.2018.00505},
	author = {Thompson, AK and Carruth, H and Haywood, R and Hill, NJ and Sarnacki, WA and McCane, LM and Jonathan Wolpaw and McFarland, DJ}
}
