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Journal of Neurophysiology

Mark M G Walton, Michael J Mustari
In pattern strabismus the horizontal and vertical misalignments vary with eye position along the orthogonal axis. The disorder is typically described in terms of overaction or underaction of oblique muscles. Recent behavioral studies in humans and monkeys, however, have reported that such actions are insufficient to fully explain the patterns of directional and amplitude disconjugacy of saccades. There is mounting evidence that the oculomotor abnormalities associated with strabismus are at least partially attributable to neurophysiological abnormalities...
September 13, 2017: Journal of Neurophysiology
Dinushi Weerasinghe, Parvathi Menon, Steve Vucic
Hyperpolarization-activated cyclic-nucleotide gated (HCN) channels mediate differences in sensory and motor axonal excitability at different thresholds in animal models. Importantly, HCN channels are responsible for voltage-gated inward rectifying (Ih) currents activated during hyperpolarization. The Ih currents exert a crucial role in determining the resting membrane potential and have been implicated in a variety of neurological disorders, including neuropathic pain. In humans, differences in biophysical properties of motor and sensory axons at different thresholds remain to be elucidated and could provide crucial pathophysiological insights in peripheral neurological diseases...
September 13, 2017: Journal of Neurophysiology
Mohammad Hossein Khani, Tim Gollisch
Retinal ganglion cells adapt to changes in visual contrast by adjusting their response kinetics and sensitivity. While much work has focused on the time scales of these adaptation processes, less is known about the spatial scale of contrast adaptation. For example, do small, localized contrast changes affect a cell's signal processing across its entire receptive field? Previous investigations have provided conflicting evidence, suggesting either that contrast adaptation occurs locally within subregions of a ganglion cell's receptive field or globally over the receptive field in its entirety...
September 13, 2017: Journal of Neurophysiology
Rasmus Feld Frisk, Peter Jensen, Henrik Kirk, Laurent J Bouyer, Jakob Lorentzen, Jens Bo Nielsen
INTRODUCTION: Exaggerated sensory activity has been assumed to contribute to functional impairment following lesion of the central motor pathway. However, recent studies have suggested that sensory contribution to muscle activity during gait is reduced in stroke patients and children with cerebral palsy (CP). We investigated whether this also occurs in CP adults and whether daily treadmill training is accompanied by alterations in sensory contribution to muscle activity. MATERIALS AND METHODS: 17 CP adults and 12 uninjured individuals participated...
September 13, 2017: Journal of Neurophysiology
Laurent Goffart, Aaron Lee Cecala, Neeraj J Gandhi
Following the suggestion that a command encoding the current target location feeds the oculomotor system during interceptive saccades, we tested the involvement of the deep superior colliculus (dSC). Extracellular activity of 52 saccade-related neurons was recorded in three monkeys while they generated saccades to targets that were static or moving along the preferred axis, away from (outward) or toward a fixated target (inward) with a constant speed (20°/s). Vertical and horizontal motions were tested when possible...
September 13, 2017: Journal of Neurophysiology
Konstantinos Kostarakos, Berthold Hedwig
We used suction electrodes to reliably record the activity of identified ascending auditory interneurons from the anterior surface of the brain in crickets. Electrodes were gently attached to the sheath covering the projection area of the ascending interneurons and the ring-like auditory neuropil in the protocerebrum. The specificity and selectivity of the recordings were determined by the precise electrode location, which could easily be changed without causing damage to the tissue. Different non-auditory fibres were recorded at other spots of the brain surface; stable recordings lasted for several hours...
September 13, 2017: Journal of Neurophysiology
Sasha Reschechtko, Mark L Latash
We combined the theory of neural control of movement with referent coordinates and the uncontrolled manifold hypothesis to explore synergies stabilizing the hand action in accurate four-finger pressing tasks. In particular, we tested a hypothesis on two classes of synergies - those among the four fingers and those within a pair of control variables - stabilizing hand action under visual feedback and disappearing without visual feedback. Subjects performed four-finger total force and moment production tasks under visual feedback; the feedback was later partially or completely removed...
September 13, 2017: Journal of Neurophysiology
Aneesha K Suresh, Jeremy Winberry, Christopher Versteeg, Raeed H Chowdhury, Tucker Tomlinson, Joshua M Rosenow, Lee E Miller, Sliman J Bensmaia
While the response properties of neurons in the somatosensory nerves and anterior parietal cortex have been extensively studied, little is known about the encoding of tactile and proprioceptive information in the cuneate nucleus (CN) or external cuneate nucleus (ECN), the first recipients of upper limb somatosensory afferent signals. The major challenge in characterizing neural coding in CN/ECN has been to record from these tiny, difficult to access brainstem structures. Most previous investigations of CN response properties have been carried out in decerebrate or anesthetized animals, thereby eliminating the well-documented top-down signals from cortex, which likely exert a strong influence on CN responses...
September 13, 2017: Journal of Neurophysiology
Qadeer Arshad, Yuliya Nigmatullina, Shuaib Siddiqui, Mustafa Franka, Saniya Mediratta, Sanjeev Ramachandaran, Rhannon Lobo, Paresh Malhotra, R Edward Roberts, Adolfo M Bronstein
Over the past decade neuroscientific research has attempted to probe the neurobiological underpinnings of human pro-social decision-making. Such research has almost ubiquitously employed tasks such as the dictator game or similar variations (i.e. ultimatum game). Considering the explicit numerical nature of such tasks, it is surprising that the influence of numerical cognition upon decision-making during task performance remains unknown. Whilst performing these tasks, participants typically tend to anchor upon a 50:50 split that necessitates an explicit numerical judgement (i...
September 13, 2017: Journal of Neurophysiology
Sandeep K Subramanian, Anatol G Feldman, Mindy F Levin
Previous motor learning studies based on adapting movements of the hemiparetic arm in stroke subjects have not accounted for spasticity occurring in specific joint ranges (spasticity zones), resulting in equivocal conclusions about learning capacity. We compared the ability of participants with stroke to rapidly adapt elbow extension movements to changing external load conditions outside and inside spasticity zones. Participants with stroke (n=12, aged: 57.8±9.6 years) and healthy age-matched controls (n=8, 63...
September 13, 2017: Journal of Neurophysiology
Peter C Zachar, Wen Pan, Michael G Jonz
The neuroepithelial cell (NEC) of the fish gill is an important model for O2 sensing in vertebrates; however, a complete picture of the chemosensory mechanisms in NECs is lacking, and O2 chemoreception in vertebrates that are tolerant to anoxia has yet not been explored. Using whole-cell patch-clamp recording, we characterized four types of ion channels in NECs isolated from the anoxia-tolerant goldfish. A Ca(2+)-dependent K(+) current (IKCa) peaked at ~20 mV, was potentiated by increased intracellular Ca(2+), and was reduced by 100 μM Cd(2+) A voltage-dependent inward current in Ba(2+) solution, with peak at 0 mV, confirmed the presence of Ca(2+) channels...
September 13, 2017: Journal of Neurophysiology
David Michael Coppola, Brittaney E Ritchie, Brent A Craven
The spatial distribution of receptors within sensory epithelia (e.g. retina and skin) is often markedly non-uniform to gain efficiency in information capture and neural processing. By contrast, odors, unlike visual and tactile stimuli, have no obvious spatial dimension. What need then could there be for either nearest-neighbor relationships or non-uniform distributions of receptor cells in the olfactory epithelium (OE)? Adrian (1942; 1950) provided the only widely debated answer to this question when he posited that the physical properties of odors, such as volatility and water solubility, determine a spatial pattern of stimulation across the OE that could aid odor discrimination...
September 6, 2017: Journal of Neurophysiology
Vicki Maria Tysseling, David A Klein, Rebecca Imhoff-Manuel, Marin Manuel, Charles J Heckman, Matthew C Tresch
Following spinal cord injury (SCI), reflexes become hyperexcitable, leading to debilitating muscle spasms and compromised motor function. Previous work has described adaptations in spinal systems that might underlie this hyperexcitability, including an increase in constitutively active 5-HT2C receptors in spinal motoneurons. That work, however, examined adaptations following complete transection SCI, whereas SCI in humans is usually anatomically and functionally incomplete. We therefore evaluated whether constitutive activity of 5-HT2C receptors contributes to reflex hyperexcitability in an incomplete compression model of SCI and to spasms in vitro and in vivo...
September 6, 2017: Journal of Neurophysiology
Lucas Samuel Baltzell, Ramesh Srinivasan, Virginia M Richards
It has been suggested that cortical entrainment plays an important role in speech perception by helping to parse the acoustic stimulus into discrete linguistic units (Giraud & Poeppel, 2012). However, the question of whether the entrainment response to speech depends on the intelligibility of the stimulus remains open. Studies addressing this question of intelligibility have, for the most part, significantly distorted the acoustic properties of the stimulus to degrade the intelligibility of the speech stimulus, making it difficult to compare across "intelligible" and "unintelligible" conditions...
September 6, 2017: Journal of Neurophysiology
Ibis M Agosto-Marlin, Gordon S Mitchell
Spinal brain derived neurotrophic factor (BDNF) is necessary and sufficient to elicit certain forms of long-lasting phrenic motor facilitation (pMF). BDNF elicits pMF by binding to its high affinity receptor tropomyosin receptor kinase B (TrkB), potentially activating multiple downstream signaling cascades. Canonical BDNF/TrkB signaling includes three pathways: 1) the Ras/RAF/MEK/ERK MAP Kinase pathway; 2) the phosphatidylinositol 3-kinase/Akt pathway; and 3) the PLCγ/PKC pathway. Here, we demonstrate that spinal BDNF-induced pMF requires PLCγ/PKCθ in normal rats, but not MEK/ERK or PI3K/Akt signaling...
August 30, 2017: Journal of Neurophysiology
Claire K Naughtin, Benjamin J Tamber-Rosenau, Paul E Dux
Individuation refers to individuals' use of spatial and temporal properties to register objects as distinct perceptual events relative to other stimuli. Although behavioural studies have examined both spatial and temporal individuation, neuroimaging investigations have been restricted to the spatial domain and at relatively late stages of information processing. Here we used univariate and multi-voxel pattern analyses of functional magnetic resonance imaging data to identify brain regions involved in individuating temporally distinct visual items, and the neural consequences that arise when this process reaches its capacity limit (Repetition Blindness [RB])...
August 30, 2017: Journal of Neurophysiology
Steven T Walston, Yao-Chuan Chang, James D Weiland, Robert H Chow
Patch clamp recordings of neurons in the inner nuclear layer of the retina are difficult to conduct in a wholemount retina preparation because surrounding neurons block the path of the patch pipette. Vertical slice preparations or dissociated retina cell cultures provide access to bipolar cells at the cost of severing lateral connection between neurons. We have developed a technique to remove photoreceptors from the rodent retina that exposes inner nuclear layer neurons, allowing access for patch clamp recording...
August 30, 2017: Journal of Neurophysiology
Brandon Wayne Collins, E W J Cadigan, Lucas Stefanelli, Duane C Button
The purpose of this study was to examine the effect of shoulder position on corticospinal excitability (CSE) of the biceps brachii during rest and a 10% maximal voluntary contraction (MVC). Participants (n=9) completed two experimental sessions with four conditions: 1) rest, 0° shoulder flexion, 2) 10% MVC, 0° shoulder flexion 3) rest, 90° shoulder flexion 4) 10% MVC, 90° shoulder flexion. Transcranial magnetic, transmastoid electrical and Erb's point stimulation were used to induce motor-evoked potentials (MEPs), cervicomedullary MEPs (CMEPs) and maximal muscle compound potentials (Mmax), respectively, in the biceps brachii in each condition...
August 30, 2017: Journal of Neurophysiology
Kate Christison-Lagay, Sharath Bennur, Yale E Cohen
A fundamental problem in hearing is detecting a "target" stimulus (e.g., a friend's voice) that is embedded in a noisy background (e.g., the din of a crowded restaurant). Despite its importance to hearing, a relationship between spiking activity and behavioral performance during such a "detection-in-noise" task has yet to be fully elucidated. Here, we recorded spiking activity in primary auditory cortex (A1) while rhesus monkeys detected a target stimulus that was embedded in a noise background. Although some neurons were modulated, the response of the typical A1 neuron was not modulated by the stimulus- and task-related parameters of our task...
August 30, 2017: Journal of Neurophysiology
Sarah M Keesom, Brooklyn G Sloss, Zita Erbowor-Becksen, Laura M Hurley
Past social experience and current social context shape the responses of animals to social signals. The serotonergic system is one potential mechanism by which both experiential and contextual factors could be conveyed to sensory systems, like the auditory system, for multiple reasons. 1) Many features of the serotonergic system are sensitive to social experience. 2) Elevations in serotonergic activity are triggered by social partners, and variation in socially triggered serotonergic responses reflect behavioral differences among social encounters...
August 30, 2017: Journal of Neurophysiology
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