@article {4492, title = {Methods for automated delineation and assessment of EMG responses evoked by peripheral nerve stimulation in diagnostic and closed-loop therapeutic applications.}, journal = {J Neural Eng}, volume = {20}, year = {2023}, month = {2023 Jul 21}, abstract = {

Surface electromyography measurements of the Hoffmann (H-) reflex are essential in a wide range of neuroscientific and clinical applications. One promising emerging therapeutic application is H-reflex operant conditioning, whereby a person is trained to modulate the H-reflex, with generalized beneficial effects on sensorimotor function in chronic neuromuscular disorders. Both traditional diagnostic and novel realtime therapeutic applications rely on accurate definitions of the H-reflex and M-wave temporal bounds, which currently depend on expert case-by-case judgment. The current study automates such judgments.Our novel wavelet-based algorithm automatically determines temporal extent and amplitude of the human soleus H-reflex and M-wave. In each of 20 participants, the algorithm was trained on data from a preliminary 3 or 4 min recruitment-curve measurement. Output was evaluated on parametric fits to subsequent sessions{\textquoteright} recruitment curves (92 curves across all participants) and on the conditioning protocol{\textquoteright}s subsequent baseline trials (\~{}1200 per participant) performed near. Results were compared against the original temporal bounds estimated at the time, and against retrospective estimates made by an expert 6 years later.Automatic bounds agreed well with manual estimates: 95\% lay within {\textpm}2.5 ms. The resulting H-reflex magnitude estimates showed excellent agreement (97.5\% average across participants) between automatic and retrospective bounds regarding which trials would be considered successful for operant conditioning. Recruitment-curve parameters also agreed well between automatic and manual methods: 95\% of the automatic estimates of the current required to elicitfell within{\textpm}1.4\%of the retrospective estimate; for the {\textquoteright}threshold{\textquoteright} current that produced an M-wave 10\% of maximum, this value was{\textpm}3.5\%.Such dependable automation of M-wave and H-reflex definition should make both established and emerging H-reflex protocols considerably less vulnerable to inter-personnel variability and human error, increasing translational potential.

}, keywords = {Electric Stimulation, Electromyography, H-Reflex, Humans, Muscle, Skeletal, Peripheral Nerves, Retrospective Studies}, issn = {1741-2552}, doi = {10.1088/1741-2552/ace6fb}, author = {McKinnon, Michael L and Hill, N Jeremy and Carp, Jonathan S and Dellenbach, Blair and Thompson, Aiko K} } @article {3100, title = {Reflex conditioning: a new strategy for improving motor function after spinal cord injury.}, journal = {Annals of the New York Academy of Sciences}, volume = {1198 Suppl 1}, year = {2010}, month = {06/2010}, pages = {E12{\textendash}E21}, abstract = {Spinal reflex conditioning changes reflex size, induces spinal cord plasticity, and modifies locomotion. Appropriate reflex conditioning can improve walking in rats after spinal cord injury (SCI). Reflex conditioning offers a new therapeutic strategy for restoring function in people with SCI. This approach can address the specific deficits of individuals with SCI by targeting specific reflex pathways for increased or decreased responsiveness. In addition, once clinically significant regeneration can be achieved, reflex conditioning could provide a means of reeducating the newly (and probably imperfectly) reconnected spinal cord.}, keywords = {H-Reflex, learning and memory, Locomotion, plasticity, reflex conditioning, Rehabilitation, spinal cord injury}, issn = {1749-6632}, doi = {10.1111/j.1749-6632.2010.05565.x}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20590534}, author = {Xiang Yang Chen and Yi Chen and Wang, Yu and Thompson, Aiko and Jonathan S. Carp and Segal, Richard L. and Jonathan Wolpaw} } @article {2164, title = {Temporal transformation of multiunit activity improves identification of single motor units.}, journal = {J Neurosci Methods}, volume = {114}, year = {2002}, month = {02/2002}, pages = {87-98}, abstract = {

This report describes a temporally based method for identifying repetitive firing of motor units. This\ approach\ is ideally suited to spike trains with negative serially correlated inter-spike intervals (ISIs). It can also be applied to spike trains in which ISIs exhibit little serial correlation if their coefficient of variation (COV) is sufficiently low. Using a novel application of the Hough transform, this method (i.e. the modified Hough transform (MHT)) maps motor unit action potential (MUAP) firing times into a feature space with ISI and offset (defined as the latency from an arbitrary starting time to the first MUAP in the train) as dimensions. Each MUAP firing time corresponds to a pattern in the feature space that represents all possible MUAP trains with a firing at that time. Trains with stable ISIs produce clusters in the feature space, whereas randomly firing trains do not. The MHT provides a direct estimate of mean firing rate and its variability for the entire data segment, even if several individual MUAPs are obscured by firings from other motor units. Addition of this method to a shape-based classification\ approach\ markedly improved rejection of false positives using simulated data and identified spike trains in whole muscle electromyographic recordings from rats. The relative independence of the MHT from the need to correctly classify individual firings permits a global description of stable repetitive firing behavior that is complementary to shape-based approaches to MUAP classification.

}, keywords = {Action Potentials, Animals, Electromyography, H-Reflex, Motor Neurons, Muscle, Skeletal, Rats, Signal Processing, Computer-Assisted}, issn = {0165-0270}, doi = {10.1016/S0165-0270(01)00517-9}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11850043}, author = {Gerwin Schalk and Jonathan S. Carp and Jonathan Wolpaw} } @article {3162, title = {Effects of chronic nerve cuff and intramuscular electrodes on rat triceps surae motor units.}, journal = {Neuroscience letters}, volume = {312}, year = {2001}, month = {10/2001}, pages = {1{\textendash}4}, abstract = {In order to assess the long-term effects of implanted electrodes on motor unit properties, we studied triceps surae (TS) motor units in rats implanted for 3-10 months with a tibial nerve cuff electrode for H-reflex elicitation and intramuscular electrodes for recording TS electromyographic activity. Motor units with sag from implanted rats displayed greater tetanic force than those from unimplanted rats. Motor units without sag had shorter twitch contraction times. This disrupted the relationship between sag and contraction time that was always present in unimplanted rats. These differences were consistent with a small degree of muscle denervation and subsequent reinnervation. Further analyses ascribed this effect to the nerve cuff rather than to the intramuscular electrodes. Comparable changes in motor unit properties may occur in humans with implanted nerve cuffs.}, keywords = {chronic recording, contraction time, H-Reflex, implanted electrodes, motor units, nerve cuff, reinnervation, sag}, issn = {0304-3940}, doi = {10.1016/S0304-3940(01)02183-8}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11578831}, author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. and Jonathan Wolpaw} } @article {3161, title = {Motor unit properties after operant conditioning of rat H-reflex.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {140}, year = {2001}, month = {10/2001}, pages = {382{\textendash}386}, abstract = {Operant conditioning of the H-reflex produces plasticity at several sites in the spinal cord, including the motoneuron. This study assessed whether this spinal cord plasticity is accompanied by changes in motor unit contractile properties. Thirty-one adult male Sprague-Dawley rats implanted for chronic recording of triceps surae electromyographic activity and H-reflex elicitation were exposed for at least 40 days to HRup or HRdown training, in which reward occurred when the H-reflex was greater than (12 HRup rats) or less than (12 HRdown rats) a criterion value, or continued under the control mode in which the H-reflex was simply measured (7 HRcon rats). At the end of H-reflex data collection, rats were anesthetized and the contractile properties of 797 single triceps surae motor units activated by intraaxonal (or intramyelin) current injection were determined. Motor units were classified as S, FR, Fint, or FF on the basis of sag and fatigue properties. Maximum tetanic force and twitch contraction time were also measured. HRdown rats exhibited a significant increase in the fatigue index of fast-twitch motor units. This resulted in a significant decrease in the percentage of Fint motor units and a significant increase in that of FR motor units. HRup conditioning had no effect on fatigue index. Neither HRup nor HRdown conditioning affected maximum tetanic force or twitch contraction time. These data are consistent with the hypothesis that conditioning mode-specific change in motoneuron firing patterns causes activity-dependent change in muscle properties.}, keywords = {H-Reflex, motor unit type, operant conditioning, plasticity, triceps surae}, issn = {0014-4819}, doi = {10.1007/s002210100830}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11681314}, author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. and Jonathan Wolpaw} } @article {3163, title = {Operant conditioning of rat H-reflex affects motoneuron axonal conduction velocity.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {136}, year = {2001}, month = {01/2001}, pages = {269{\textendash}273}, abstract = {This study assessed the effects of operant conditioning of the H-reflex on motoneuron axonal conduction velocity in the rat. After measurement of the control H-reflex size, rats were either exposed for at least 40 days to the HRup or HRdown conditioning mode, in which reward occurred only if the soleus H-reflex was greater than (HRup mode) or less than (HRdown mode) a criterion or continued under the control condition (HRcon mode) in which the H-reflex was simply measured. We then measured axonal conduction velocity of triceps surae motor units of HRup, HRdown, and HRcon rats by stimulating the axon in the ventral root and recording from the tibial nerve. Conduction velocity was 8\% less in successful HRdown rats than in HRcon rats (P=0.02). Conduction velocity in HRup rats and unsuccessful HRdown rats was not significantly different from that in HRcon rats. Since recording bypassed the intra-spinal portion of the motoneuron, the change was clearly in the axon. This decrease was similar to the 6\% decrease previously found in successful HRdown monkeys. Unsuccessful HRdown rats and monkeys did not show this decrease. This result suggests that the mechanism of HRdown conditioning is similar in rats and monkeys and provides further support for the hypothesis that HRdown conditioning decreases motoneuron excitability by producing a positive shift in firing threshold. While traditional theories of learning emphasize synaptic plasticity, neuronal plasticity may also contribute to operantly conditioned behavioral changes.}, keywords = {conduction velocity, H-Reflex, motoneuron, plasticity, Spinal Cord}, issn = {0014-4819}, doi = {10.1007/s002210000608}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11206290}, author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. and Jonathan Wolpaw} } @article {3172, title = {Operant conditioning of the primate H-reflex: factors affecting the magnitude of change.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {97}, year = {1993}, month = {12/1993}, pages = {31{\textendash}39}, abstract = {Primates can gradually increase or decrease H-reflex amplitude in one leg when reward depends on that amplitude. The magnitude of change varies greatly from animal to animal. This study sought to define the factors that control this magnitude. It evaluated the influence of animal age, muscle size (absolute and relative), background electromyographic activity (EMG) level, M response amplitude, initial H-reflex amplitude, performance intensity, and behavior of the contralateral leg. Fifty-four animals (Macaca nemestrina) underwent operant conditioning of the triceps surae H-reflex in one leg (the trained leg). Twenty-eight were rewarded for larger H-reflexes (HRup animals), and 26 were rewarded for smaller H-reflexes (HRdown animals). In the HRup animals, H-reflex amplitude in the trained leg rose to an average final value of 177\% of its initial amplitude. Magnitude of increase varied widely across animals. Nine animals rose to 120-140\%, 11 to 160-240\%, three to 300\% or more, and five remained within 20\% of initial amplitude. In the HRdown animals, H-reflex amplitude in the trained leg decreased to an average of 69\% of initial amplitude. Magnitude of decrease varied widely. Five animals decreased to 20-40\%, seven to 40-60\%, six to 60-80\%, and eight remained within 20\% of initial amplitude. Animal age, as assessed by weight, markedly affected HRdown conditioning, but not HRup conditioning. Heavy HRdown animals (> or = 6 kg) were more successful than light HRdown animals (< 6 kg). Thirteen of 14 heavy animals and only five of 12 light animals decreased to less than 80\% of initial amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)}, keywords = {H-Reflex, monkey, operant conditioning, plasticity, Spinal Cord}, issn = {0014-4819}, doi = {10.1007/BF00228815}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8131830}, author = {Jonathan Wolpaw and Herchenroder, P. A. and Jonathan S. Carp} }