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Journal of Neurophysiology

Rositsa Raikova, Jan Celichowski, Silvija Angelova, Piotr Krutki
The muscle force is the sum of forces of multiple motor units (MUs), which have different contractile properties. During movements, MUs develop unfused tetani, which result from summation of twitch-shape responses to individual stimuli, which are variable in amplitude and duration. The aim of the study was to develop a realistic muscle model that would integrate previously developed models of MU contractions and an algorithm for the prediction of tetanic forces. The proposed model of rat medial gastrocnemius muscle is based on physiological data: excitability and firing frequencies of motoneurons, contractile properties, and the number and proportion of MUs in the muscle...
July 18, 2018: Journal of Neurophysiology
Bryan James Black, Aswini Kanneganti, Alexandra Joshi-Imre, Rashed Rihani, Bitan Chakraborty, Justin Abbott, Joseph J Pancrazio, Stuart F Cogan
Multisite implantable electrode arrays serve as a tool to understand cortical network connectivity and plasticity. Furthermore, they enable electrical stimulation to drive plasticity, study motor/sensory mapping, or provide network input for controlling brain-computer interfaces. Neurobehavioral rodent models are prevalent in studies of motor cortex injury and recovery as well as restoration of auditory/visual cues due to their relatively low cost and ease of training. Therefore, it is important to understand the chronic performance of relevant electrode arrays in rodent models...
July 18, 2018: Journal of Neurophysiology
Rohan Puri, Tess Nikitenko, Sarah Kemp
Many everyday actions require inhibitory control. The success of these actions depends on the availability of prior information regarding stopping demands. Using transcranial magnetic stimulation (TMS), Cirillo and colleagues (2017) provide novel neurophysiological evidence for distinct roles of intracortical inhibitory mechanisms underlying inhibitory control. Other, non-exclusive mechanisms such as disfacilitation of excitatory pathways and interhemispheric inhibition may also contribute to inhibitory control...
July 18, 2018: Journal of Neurophysiology
Matthew Karl Kirchner, Robert C Foehring, Joseph C Callaway, William E Armstrong
Magnocellular oxytocin (OT) and vasopressin (VP) neurons express an afterhyperpolarization (AHP) following spike trains that attenuates firing rate and contributes to burst patterning. This AHP includes contributions from an apamin-sensitive, medium duration AHP (mAHP) and from an apamin-insensitive, slow duration AHP (sAHP). These AHPs are Ca2+ dependent and activated by Ca2+ influx through voltage-gated Ca2+ channels. Across central nervous system neurons that generate Ca2+ - dependent AHPs, the Ca2+ channels that couple to the mAHP and sAHP differ greatly, but for MNCs this relationship is unknown...
July 18, 2018: Journal of Neurophysiology
Kevin A Mazurek, Michael Berger, Tejapratap Bollu, Raeed H Chowdhury, Naveen Elangovan, Irene A Kuling, M Hongchul Sohn
No abstract text is available yet for this article.
July 18, 2018: Journal of Neurophysiology
Daniel Preciado, Jan Theeuwes
The current eye-tracking study examined the influence of reward on oculomotor performance, and the extent to which learned stimulus-reward associations interacted with voluntary oculomotor control with a modified paradigm based on the classical anti-saccade task. Participants were shown two equally salient stimuli simultaneously: a gray and a colored circle, and were instructed to make a fast saccade to one of them. During the first phase of the experiment, participants made a fast saccade towards the colored stimulus, and their performance determined a (cash) bonus...
July 18, 2018: Journal of Neurophysiology
Corey Scott Shayman, Jae-Hyun Seo, Yonghee Oh, Richard F Lewis, Robert J Peterka, Timothy E Hullar
A single event can generate asynchronous sensory cues due to variable encoding, transmission, and processing delays. To be interpreted as being associated in time, these cues must occur within a limited time window, referred to as a "temporal binding window" (TBW). We investigated the hypothesis that vestibular deficits could disrupt temporal visual-vestibular integration by determining the relationships between vestibular threshold and TBW in participants with normal vestibular function and with vestibular hypofunction...
July 18, 2018: Journal of Neurophysiology
Nicholas Maling, Scott F Lempka, Zack Blumenfeld, H M Bronte-Stewart, Cameron C McIntyre
Clinical deep brain stimulation (DBS) technology is evolving to enable chronic recording of local field potentials (LFPs) that represent electrophysiological biomarkers of the underlying disease state. However, little is known about the biophysical basis of LFPs, or how the patient's unique brain anatomy and electrode placement impact the recordings. Therefore, we developed a patient-specific computational framework to analyze LFP recordings within a clinical DBS context. We selected a subject with Parkinson's disease implanted with a Medtronic Activa PC+S DBS system and reconstructed their subthalamic nucleus (STN) and DBS electrode location using medical imaging data...
July 18, 2018: Journal of Neurophysiology
Sasha N Zill, Chris J Dallmann, Ansgar Büschges, Sumaiya Chaudhry, Josef Schmitz
Many sensory systems are tuned to specific parameters of behaviors and have effects that are task-specific. We have studied how force feedback contributes to activation of synergist muscles in serially homologous legs of stick insects. Forces were applied using conventional half sine or ramp and hold functions. We also utilized waveforms of joint torques calculated from experiments in freely walking animals. In all legs, forces applied to either the tarsus (foot) or proximal leg segment (trochanter) activated synergist muscles that generate substrate grip and support but coupling of the depressor muscle to tarsal forces was weak in the front legs...
July 18, 2018: Journal of Neurophysiology
Alexander Stamenkovic, Paul J Stapley, Rebecca K Robins, Mark A Hollands
If a whole-body reaching task is produced when standing or adopting challenging postures, it is unclear whether changes in attentional demands or the sensorimotor integration necessary for balance control influence the interaction between visuomotor and postural components of the movement. Is gaze control prioritized by the CNS to produce coordinated eye movements with the head and whole-body regardless of movement context? Considering the coupled nature of visuomotor and whole-body postural control during action, this study aimed to understand how changing equilibrium constraints (in the form of different postural configurations) influenced the initiation of eye, head and arm movements...
July 18, 2018: Journal of Neurophysiology
Robertas Guzulaitis, Jorn Hounsgaard
Synaptic activity in motoneurons may provide unique insight in the relation between functional network activity and behavior. During scratch network activity in an ex-vivo preparation from red-eared turtles (Trachemys scripta elegans) excitatory and inhibitory synaptic current can be separated and quantified in voltage clamp recordings. With this technique we confirm the reciprocal synaptic excitation and inhibition in hip flexor motoneurons during ipsilateral scratching and show that out-of-phase inhibition and excitation also characterize hip extensor motoneurons during ipsi- and contralateral scratching...
July 11, 2018: Journal of Neurophysiology
Daniel Birman, Justin L Gardner
Despite the central use of motion visibility to reveal the neural basis of perception, perceptual decision making, and sensory inference there exists no comprehensive quantitative framework establishing how motion visibility parameters modulate human cortical response. Random-dot motion stimuli can be made less visible by reducing image contrast or motion coherence, or by shortening the stimulus duration. Because each of these manipulations modulates the strength of sensory neural responses they have all been extensively used to reveal cognitive and other non-sensory phenomenon such as the influence of priors, attention, and choice-history biases...
July 11, 2018: Journal of Neurophysiology
Andrew Sawers, Tanvi Bhatt
Is there a neuromuscular basis for falls? If so it may provide new insight into falls, their assessment and treatment. We hypothesized that falls and recoveries from a laboratory-induced slip would be characterized by differences in multi-muscle coordination patterns. Using muscle synergy analysis we identified different multi-muscle coordination patterns between older adults who fell and those who recovered from a laboratory-induced "feet-forward" slip. Participants who fell recruited fewer muscle synergies than participants who recovered...
July 11, 2018: Journal of Neurophysiology
Clara Bourrelly, Julie Quinet, Laurent Goffart
The caudal fastigial nuclei (cFN) are the output nuclei by which the medio-posterior cerebellum influences the production of saccadic and pursuit eye movements. We investigated the consequences of unilateral inactivation on the pursuit eye movement made immediately after an interceptive saccade toward a centrifugal target. We describe here the effects when the target moved along the horizontal meridian with a 10 or 20{degree sign}/s speed. After muscimol injection, the monkeys were unable to track the current location of the moving target...
July 11, 2018: Journal of Neurophysiology
Sigge Weisdorf, Sirin Wilhelmsen Gangstad, Jonas Duun-Henriksen, Karina Sif Søndergaard Mosholt, Troels Wesenberg Kjær
Subcutaneous recording of electroencephalography (EEG) potentially enables ultra-long-term epilepsy monitoring in real-life conditions due to increased mobility and discreteness. This study is the first to compare physiological and epileptiform EEG signals from subcutaneous and scalp EEG recordings in epilepsy patients. Four patients with probable or definite temporal lobe epilepsy were monitored with simultaneous scalp and subcutaneous EEG recordings. EEG recordings were compared by correlation and time-frequency analysis across an array of clinically relevant waveforms and patterns...
July 11, 2018: Journal of Neurophysiology
Sebastian M Frank, Mark W Greenlee
Here, we review the structure and function of a core region in the vestibular cortex of humans that is located in the mid-posterior Sylvian fissure and referred to as the parieto-insular vestibular cortex (PIVC). Previous studies have investigated PIVC by using vestibular or visual motion stimuli and have observed activations that were distributed across multiple anatomical structures, including the temporo-parietal junction, retroinsula, parietal operculum, and posterior insula. However, it has remained unclear whether all of these anatomical areas correspond to PIVC and whether PIVC responds to both vestibular and visual stimuli...
July 11, 2018: Journal of Neurophysiology
Fernando Chaure, Hernan Gonzalo Rey, Rodrigo Quian Quiroga
The most widely used spike sorting algorithms are semiautomatic in practice, requiring manual tuning of the automatic solution to achieve good performance. In this work, we propose a new fully automatic spike sorting algorithm that can capture multiple clusters of different size and densities. In addition, we introduce an improved feature selection method by using a variable number of wavelet coefficients based on the degree of non-gaussianity of their distributions. We evaluated the performance of the proposed algorithm with real and simulated data...
July 11, 2018: Journal of Neurophysiology
Brian J Schriver, Svetlana Bagdasarov, Qi Wang
Non-luminance-mediated changes in pupil size have been widely used to index arousal state. Recent animal studies have demonstrated correlations between behavioral-state-related pupil dynamics and sensory processing. However, the relationship between pupil-linked arousal and behavior in animals performing perceptual tasks has not been fully elucidated. In the present study, we trained head-fixed rats to discriminate between directions of whisker movements using a Go/No-Go discrimination paradigm while imaging their pupils...
July 11, 2018: Journal of Neurophysiology
Pavel Anatolyevich Puzerey, Kamal Maher, Nikil Prasad, Jesse Heymann Goldberg
Cholinergic inputs to cortex modulate plasticity and sensory processing, yet little is known about their role in motor control. Here we show that cholinergic signaling in the songbird vocal motor cortex-like nucleus RA (robust nucleus of the arcopallium) is required for song learning. Reverse microdialysis of nicotinic and muscarinic receptor antagonists into RA in juvenile birds did not significantly affect syllable timing or acoustic structure during vocal babbling. Yet chronic blockade over weeks reduced singing quantity and impaired learning, resulting in an impoverished song with excess variability, abnormal acoustic features and reduced similarity to tutor song...
July 11, 2018: Journal of Neurophysiology
Anouk J de Brouwer, Mohammed Albaghdadi, J Randall Flanagan, Jason P Gallivan
Successful motor performance relies on our ability to adapt to changes in the environment by learning novel mappings between motor commands and sensory outcomes. Such adaptation is thought to involve two distinct mechanisms: An implicit, error-based component linked to slow learning and an explicit, strategic component linked to fast learning and savings (i.e., faster re-learning). Because behavior, at any given moment, is the resultant combination of these two processes, it has remained a challenge to parcellate their relative contributions to performance...
July 11, 2018: Journal of Neurophysiology
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