Journal of Neurophysiology

In this episode, Justin W. Andrushko discusses the recently published research titled "Activity in the pontine reticular nuclei scales with handgrip force in humans." In this study, the authors used a task-based functional magnetic resonance imaging (fMRI) paradigm to show that activity in the pontine reticular nuclei scales linearly with increasing force during a handgrip task. These findings directly support recently proposed hypotheses that the reticulospinal tract may play an important role in modulating force production in humans. Article Citation: Activity in the pontine reticular nuclei scales with handgrip force in humans Tyler L. Danielson, Layla A. Gould, Jason M. DeFreitas, Rob J. MacLennan, Chelsea Ekstrand, Ron Borowsky, Jonathan P. Farthing, and Justin W. Andrushko Journal of Neurophysiology 2024 131:5, 807-814

In this episode of JNP's micro podcasts, Jessica R. Whitaker-Fornek of the University of Michigan Medical School discusses the recently published research titled "Inhibitory synaptic transmission is impaired in the Kölliker-Fuse of male, but not female, Rett syndrome mice." NEW & NOTEWORTHY Kölliker-Fuse (KF) neurons in acute brain slices from male Rett syndrome (RTT) mice receive reduced inhibitory synaptic inputs compared with wild-type littermates. In female RTT mice, inhibitory transmission was not different in KF neurons compared with controls. The results from this study show that sex-specific alterations in synaptic transmission occur in the KF of RTT mice. Inhibitory synaptic transmission is impaired in the Kölliker-Fuse of male, but not female, Rett syndrome mice Jessica R. Whitaker-Fornek, Paul M. Jenkins, and Erica S. Levitt Journal of Neurophysiology 2023 130:6, 1578-1587

In this episode Mark F. Walker of Case Western Reserve University, discusses the recently published research titled "Short-term learning of the vestibulo-ocular reflex induced by a custom interactive computer game." NEW & NOTEWORTHY This study demonstrates the feasibility and efficacy of a customized computer game to induce motor learning in the high-frequency rotational vestibulo-ocular reflex. It provides a physiological basis for the deployment of this technology to clinical vestibular rehabilitation. Article Citation: Short-term learning of the vestibulo-ocular reflex induced by a custom interactive computer game Qi Li, Honglu Xu, Weicong Chen, Andrew Su, Michael J. Fu, and Mark F. Walker Journal of Neurophysiology 2024 131:1, 16-27

In this podcast Brittany Heintz Walters of Seattle University discusses the recently published research titled "Visual feedback and declines in attention are associated with altered visual strategy during a force-steadiness task in older adults." NEW & NOTEWORTHY This study contributes novel findings of age-related changes in visual strategy and associations with attentional deficits during hand motor tasks. Older adults used fewer saccades than young adults and with higher versus lower gain visual feedback during a force-steadiness task. A subset of older adults used an altered visual strategy when allocating attention across multiple tasks. Given that this subset demonstrated attentional deficits, the altered visual strategy could serve to indicate motor and/or cognitive impairments. Article Citation: Visual feedback and declines in attention are associated with altered visual strategy during a force-steadiness task in older adults Brittany Heintz Walters, Wendy E. Huddleston, Kristian O’Connor, Jinsung Wang, Marie Hoeger Bement, and Kevin G. Keenan Journal of Neurophysiology 2023 130:5, 1309-1320

In this podcast Dr. Peka Christova of The Neuroimaging Research Group, Brain Sciences Center discusses the recently published Short Report titled "Changes of gray matter volumes of subcortical regions across the lifespan: a Human Connectome Project study." NEW & NOTEWORTHY Christova et al. report mixed effects of age on subcortical grey matter volume (GMV) during lifespan (n = 2458, 5-90 yr old, 1113 male, 1345 female). Striatal and cerebellar GMVs decreased linearly with age, more steeply in males. In contrast, GMVs of the amygdala, pallidum, thalamus, ventral diencephalon, and brainstem changed in a quadratic fashion, increasing first and decreasing afterward, with males peaking earlier than females in all regions but the brainstem where they peaked at nearly the same time. Article Citation: Changes of gray matter volumes of subcortical regions across the lifespan: a Human Connectome Project study Peka Christova and Apostolos P. Georgopoulos Journal of Neurophysiology 2023 130:5, 1303-1308

In this episode, Lydiane Lauzier of Université du Québec à Chicoutimi discusses the recently published article “Variation of corticospinal excitability during kinesthetic illusion induced by musculotendinous vibration.” New and Noteworthy: The modulation of corticospinal excitability when perceiving a vibration (VIB)-induced kinesthetic illusion evolves dynamically over time. This modulation might be linked to the delayed occurrence and progressive increase in strength of the illusory perception in the first seconds after VIB start. Different spinal/cortical mechanisms could be at play during VIB, depending on the tested muscle, presence/absence of an illusion, and the specific timing at which corticospinal drive is tested pre/post VIB. Article Citation: Variation of corticospinal excitability during kinesthetic illusion induced by musculotendinous vibration Lydiane Lauzier, Marie-Pier Perron, Laurence Munger, Émilie Bouchard, Jacques Abboud, François Nougarou, and Louis-David Beaulieu Journal of Neurophysiology 2023 130:5, 1118-1125

In this podcast, author Jian Carlo Nocon (Boston University) discusses the recently published research titled "A robust and compact population code for competing sounds in auditory cortex." NEW & NOTEWORTHY Little is known about how populations of neurons within cortical circuits encode sensory stimuli in the presence of competing stimuli at other spatial locations. Here, the authors investigate this problem in auditory cortex using a recently proposed information-theoretic approach. They found a small subset of neurons nearly maximizes information about target sounds in the presence of competing maskers, approaching information levels for isolated stimuli, and provides a noise-robust code for sounds in a complex auditory scene. Article Citation: A robust and compact population code for competing sounds in auditory cortex Jian Carlo Nocon, Jake Witter, Howard Gritton, Xue Han, Conor Houghton, and Kamal Sen Journal of Neurophysiology 2023 130:3, 775-787

In this podcast coauthor Daniel Free of Brigham Young University talks about the recently published article titled “Essential tremor accentuates the pattern of tremor-band coherence between upper limb muscles.” NEW & NOTEWORTHY This research characterized the relationships in tremor-band activity between the 15 major superficial upper limb muscles of persons with essential tremor by quantifying the proportion of shared activity (coherence) in the tremor band and by characterizing phase differences between these muscles during various tasks. From the authors observations, they conclude that tremor enhances the coherence between muscle pairs throughout the upper limb in a pattern that reflects functional relationship between them. Article Citation: Essential tremor accentuates the pattern of tremor-band coherence between upper limb muscles Daniel B. Free, Ian Syndergaard, Adam C. Pigg, Silvia Muceli, Johanna Thompson-Westra, Karin Mente, Carine W. Maurer, Dietrich Haubenberger, Mark Hallett, Dario Farina, and Steven K. Charles Journal of Neurophysiology 2023 129:3, 524-540

In this podcast Nick Kitchen and Jisung Yuk of Pennsylvania State University discuss the recently published manuscript “Bilateral arm movements are coordinated via task-dependent negotiations between independent and codependent control, but not by a “coupling” control policy.” NEW & NOTEWORTHY Minimization of performance and control costs and efferent coupling between bilaterally homologous muscle groups have been separately hypothesized to describe patterns of bimanual coordination. Here, we address whether the mechanisms mediating independent and codependent control between limbs can be weighted for successful task performance. Using bilaterally asymmetric visuomotor gain perturbations, we show bimanual coordination can be characterized as a negotiation along a spectrum between extremes of independent and codependent control, but not efferent control coupling. Article Citation: Bilateral arm movements are coordinated via task-dependent negotiations between independent and codependent control, but not by a “coupling” control policy Nick M. Kitchen, Jisung Yuk, Andrzej Przybyla, Robert A. Scheidt, and Robert L. Sainburg Journal of Neurophysiology 2023 130:3, 497-515

Margaret Chow and Celia Fernandez Brillet of Johns Hopkins School of Medicine discuss the recently published manuscript titled "Binocular 3-D otolith-ocular reflexes: responses of chinchillas to natural and prosthetic stimulation after ototoxic injury and vestibular implantation." NEW & NOTEWORTHY Previous studies to expand the scope of prosthetic stimulation of the otolith end organs showed that selective stimulation of the utricle and saccule is possible. This article further defines those possibilities by characterizing a diseased animal model and subsequently studying its responses to electrical stimulation alone and in combination with mechanical motion. We show that we can partially restore responses to tilt and translation in animals with unilateral gentamicin ototoxic injury and contralateral surgical disruption. Article Citation: Binocular 3-D otolith-ocular reflexes: responses of chinchillas to natural and prosthetic stimulation after ototoxic injury and vestibular implantation Margaret R. Chow, Celia Fernandez Brillet, Kristin N. Hageman, Dale C. Roberts, Andrianna I. Ayiotis, Razi M. Haque, and Charles C. Della Santina Journal of Neurophysiology 2023 129:5, 1157-1176

In this paper first author Kelly H. Lee, and Alex Prosserman, an expert in the field discuss the recently published article titled “Cholinergic depolarization recruits a persistent Ca2+ current in Aplysia bag cell neurons.” NEW & NOTEWORTHY Ionotropic acetylcholine receptors mediate brief synaptic communication, including in bag cell neurons of the sea snail Aplysia. However, this study demonstrates that cholinergic depolarization can open a voltage-gated persistent Ca2+ current, which extends the bag cell neuron response to acetylcholine. Bursting in these neuroendocrine cells results in hormone release and egg laying. Thus, this emphasizes the role of ionotropic signaling in reaching a depolarized level to engage Ca2+ influx and perpetuating the activity necessary for behavior. Article Citation: Cholinergic depolarization recruits a persistent Ca2+ current in Aplysia bag cell neurons Kelly H. Lee, David E. Wassef, Eammon K. MacNeil, and Neil S. Magoski Journal of Neurophysiology 2023 129:5, 1045-1060

In this podcast Dr. Elijah Haynes and Dr. Jennifer Jakobi of the University of British Columbia Okanagan, and Dr. Jayne Kalmar of the Wilfrid Laurier University discuss the recently published Systematic Review titled “A systematic review of how cannabinoids affect motoneuron output.” This scoping review involved the synthesis of evidence from literature published before August 2022 about the effects of cannabinoids on quantifiable measures of motoneuron output. It contributes to understanding the effects of endocannabinoids on synaptic integration at the motoneuron and modulation of motor output. Article Citation: A systematic review of how cannabinoids affect motoneuron output Elijah M. K. Haynes, Jayne M. Kalmar, Mathew Vis-Dunbar, Kathryn M. Crosby, Angitha Mriduraj, and Jennifer M. Jakobi Journal of Neurophysiology 2023 130:2, 247-263

In this podcast co lead author Alexander M. Zero of The University of Western Ontario discusses the recently published research titled "Motor unit firing rates in young and very old adult males during an isokinetic fatiguing task and short-term recovery in the anconeus muscle." NEW & NOTEWORTHY Maximal motor unit firing rates were recorded during an isokinetic fatiguing protocol and short-term recovery in young and very old adult males. Prior studies were limited to isometric fatiguing tasks. Despite the old being ∼37% weaker and less fatigable, anconeus rates during elbow extension declined with fatigue and recovered similarly to young males. Therefore, it is unlikely that greater fatigue resistance of very old males during isokinetic contractions is related to differences in motor unit rates. Article Citation: Motor unit firing rates in young and very old adult males during an isokinetic fatiguing task and short-term recovery in the anconeus muscle Alexander M. Zero, Eric A. Kirk, Kevin J. Gilmore, and Charles L. Rice Journal of Neurophysiology 2023 130:1, 179-188

In this podcast Robert E. Kass of Carnegie Mellon University discusses the recently published review article titled "Identification of interacting neural populations: methods and statistical considerations." Abstract: As improved recording technologies have created new opportunities for neurophysiological investigation, emphasis has shifted from individual neurons to multiple populations that form circuits, and it has become important to provide evidence of cross-population coordinated activity. We review various methods for doing so, placing them in six major categories while avoiding technical descriptions and instead focusing on high-level motivations and concerns. Our aim is to indicate what the methods can achieve and the circumstances under which they are likely to succeed. Toward this end, we include a discussion of four cross-cutting issues: the definition of neural populations, trial-to-trial variability and Poisson-like noise, time-varying dynamics, and causality. Article Citation: Identification of interacting neural populations: methods and statistical considerations Robert E. Kass, Heejong Bong, Motolani Olarinre, Qi Xin, and Konrad N. Urban Journal of Neurophysiology 2023 130:3, 475-496

In this podcast Xiaoxuan Ren, Ilhan Bok, Adam Vareberg, and Prof. Aviad Hai of the University of Wisconsin-Madison discuss their recently published Innovative Methodology titled "Stimulation-mediated reverse engineering of silent neural networks." NEW & NOTEWORTHY We introduce a new concept for reverse engineering silent neuronal networks using a supervised learning algorithm combined with stimulation. We quantify the performance of the algorithm and the precision of deriving synaptic weights in inhibitory and excitatory subpopulations. We then show that stimulation enables deciphering connectivity of heterogeneous circuits fed with real electrode array recordings, which could extend in the future to deciphering connectivity in broad biological and artificial neural networks. Article Citation: Stimulation-mediated reverse engineering of silent neural networks Xiaoxuan Ren, Ilhan Bok, Adam Vareberg, and Aviad Hai Journal of Neurophysiology 2023 129:6, 1505-1514

In our latest podcast Prof. Apostolos P. Georgopoulos discusses recently published Short Report titled "Changes of cortical gray matter volume during development: a Human Connectome Project study." NEW & NOTEWORTHY We report mixed effects of age on cortical gray matter volume during development in a large sample of 649 participants studied in an identical manner (6–21 yr old, 299 males, 350 females). Volumes of 30/35 cortical areas decreased with age, temporal pole increased, and pericalcarine and hippocampal cortex (hippocampus, parahippocampal, and entorhinal) did not change. These findings were very similar in both sexes and provide a solid base for assessing region-specific cortical changes during development. Article Citation: Changes of cortical gray matter volume during development: a Human Connectome Project study Peka Christova and Apostolos P. Georgopoulos Journal of Neurophysiology 2023 130:1, 117-122

In this podcast Dr. Todd Silverstein of Willamette University discusses his recently published review titled "Lee’s “Transmembrane Electrostatically-Localized Proton” model does NOT offer a better understanding of neuronal transmembrane potentials." NEW & NOTEWORTHY In this manuscript I critique a 2020 J. Neurophysiol. paper by James W. Lee. His TELP hypothesis 1) mispredicts the resting neuron’s excess of external chloride; 2) predicts the preponderance of surface H+ over Na+ using ΔG° rather than ΔG; 3) mispredicts the dependence of the neuronal resting potential on external [Na+], [K+], and [Cl−]; 4) neither cites experimental results nor proposes experiments to test his hypothesis; and 5) presents a problematic characterization of the purpose of myelin. Article Citation: Lee’s “Transmembrane Electrostatically-Localized Proton” model does NOT offer a better understanding of neuronal transmembrane potentials Todd P. Silverstein Journal of Neurophysiology 2023 130:1, 123-127

In this micro podcast Mitchell Adrien St. Pierre and Minoru Shinohara of the Georgia Institute of Technology discuss their recently published manuscript "Transcutaneous vagus nerve stimulation at nonspecific timings during training can compromise motor adaptation in healthy humans." NEW & NOTEWORTHY Adding vagus nerve stimulation via implanted electrodes during motor training can facilitate motor recovery in disabled animals and humans. No study examined the effect of transcutaneous vagus nerve stimulation (tVNS) during training on neuromotor adaptation in healthy humans. We have found that adding tVNS at nonspecific timings during motor skill training can compromise motor adaptation but not transfer in healthy humans. Article Citation: Transcutaneous vagus nerve stimulation at nonspecific timings during training can compromise motor adaptation in healthy humans Mitchell Adrien St. Pierre and Minoru Shinohara Journal of Neurophysiology 2023 130:1, 212-223

In this micro podcast Dr. Tea Lulic-Kuryllo and Dr. David Lipps of the University of Michigan discuss their recently published research titled "Assessing shoulder muscle stretch reflexes following breast cancer treatment and postmastectomy breast reconstruction." NEW & NOTEWORTHY Shoulder muscle stretch reflexes may be impacted following postmastectomy breast reconstruction and chemoradiation. Here, we examined short- and long-latency shoulder muscle stretch reflexes in two experiments following common breast reconstruction procedures and chemoradiation. We show impairments in pectoralis major stretch reflexes following postmastectomy breast reconstruction and pectoralis major and deltoid muscle stretch reflexes following chemoradiation. These findings indicate that breast cancer treatments alter the regulation of shoulder muscle stretch reflexes. Citation Assessing shoulder muscle stretch reflexes following breast cancer treatment and postmastectomy breast reconstruction Tea Lulic-Kuryllo, Joshua M. Leonardis, Adeyiza O. Momoh, and David B. Lipps Journal of Neurophysiology 2023 129:4, 914-926

In this podcast Aiko Thompson and Alan Phipps of the Medical University of South Carolina talk about their recently published manuscript titled "Altered cutaneous reflexes to non-noxious stimuli in the triceps surae of people with chronic incomplete spinal cord injury" NEW & NOTEWORTHY This study examined modulation of the triceps surae cutaneous reflexes during standing and walking and the relationship between cutaneous and H-reflexes in people with chronic incomplete spinal cord injury (SCI). In people with SCI, the normal task-dependent, nerve-specific modulation of triceps cutaneous reflexes was missing. Cutaneous and H-reflexes were not correlated. Together with other spinal reflexes, cutaneous reflexes may serve as important biomarkers for the state of spinal interneuronal pathways. Citation Altered cutaneous reflexes to non-noxious stimuli in the triceps surae of people with chronic incomplete spinal cord injury Alan M. Phipps and Aiko K. Thompson Journal of Neurophysiology 2023 129:3, 513-523