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Journal of Neurophysiology

Blake Scott Porter, Kristin L Hillman, David K Bilkey
An animal's ability to assess the value of their behaviors in order to minimize energy use while maximizing goal achievement is critical to its survival. The anterior cingulate cortex (ACC) has been previously shown to play a critical role in this behavioral optimization process, especially when animals are faced with effortful behaviors. In the present study we designed a novel task to investigate the role of the ACC in evaluating behaviors that varied in effort but all resulted in the same outcome. We recorded single unit activity from the ACC as rats ran back and forth in a shuttle box that could be tilted to different tilt angles (0°, 15°, & 25°) in order to manipulate effort...
January 9, 2019: Journal of Neurophysiology
Shihao Lin, Yaqing Li, Ana M Lucas-Osma, Krishnapriya Hari, Marilee J Stephens, Rahul Singla, Heckman C J, Ying Zhang, Karim Fouad, Keith K Fenrich, David J Bennett
Spinal cord injury leads to a devastating loss of motor function and yet is accompanied by a paradoxical emergence of muscle spasms, which often involve complex muscle activation patterns across multiple joints, reciprocal muscle timing, and rhythmic clonus. Here we investigated the hypothesis that spasms are a manifestation of partially recovered function in spinal central pattern generating (CPG) circuits that normally coordinate complex postural and locomotor functions. We focused on the commissural propriospinal V3 neurons that coordinate inter-limb movements during locomotion, and examined mice with a chronic spinal transection...
January 9, 2019: Journal of Neurophysiology
Aiko K Thompson, Gina Fiorenza, Lindsay Smyth, Briana Favale, Jodi A Brangaccio, Janice Sniffen
Foot drop is very common among people with chronic incomplete spinal cord injury (SCI) and likely stems from SCI that disturbs the corticospinal activation of the ankle dorsiflexor tibialis anterior (TA). Thus, if one can recover or increase the corticospinalexcitability reduced by SCI, motor function recovery may be facilitated. Here, we hypothesized that in people suffering from weak dorsiflexiondue to chronic incomplete SCI, increasing the TA motor evoked potential (MEP)through operant up-conditioning can improve dorsiflexion during locomotion, while in people without any injuries, it would have little impact on already normal locomotion...
January 9, 2019: Journal of Neurophysiology
Fangyun Tian, Tiecheng Liu, Gang Xu, Talha Ghazi, Azeem Sajjad, Peter Farrehi, Michael Mei-Hwa Wang, Jimo Borjigin
Sudden death is an important but under-recognized consequence of stroke. Acute stroke can disturb central control of autonomic function, and result in cardiac dysfunction and sudden death. Previous study showed that bilateral common carotid artery ligation (BCCAL) in spontaneously hypertensive stroke-prone rats (SHRSP) is a well-established model for forebrain ischemic sudden death. This study aims to investigate the temporal dynamic changes in electrical activities of the brain and heart and functional interactions between the two vital organs following forebrain ischemia...
January 9, 2019: Journal of Neurophysiology
Ana M Lucas-Osma, Yaqing Li, Katherine C Murray, Shihao Lin, Sophie Black, Marilee J Stephens, Andrew H Ahn, Charles J Heckman, Keith K Fenrich, Karim Fouad, David J Bennett
The monosynaptic stretch reflex (MSR) plays an important role in feedback control of movement and posture, but can also lead to unstable oscillations associated with tremor and clonus, especially when increased with spinal cord injury (SCI). To control the MSR and clonus after SCI we examined how serotonin regulates the MSR in the sacrocaudal spinal cord of rats with and without a chronic spinal transection. In chronic spinal rats, numerous 5-HT receptor agonists, including zolmitriptan, methylergonovine and 5-HT, inhibited the MSR with a potency highly correlated to their binding affinity to 5-HT1D receptors and not other 5-HT receptors...
January 9, 2019: Journal of Neurophysiology
Jack Brooks, Tatjana Seizova-Cajic, Janet L Taylor
Weak electro-cutaneous stimuli applied to the forearm are erroneously localized toward its middle (Steenbergen et al. 2014). We asked whether mechanical touch stimuli exhibit a similar bias, and whether the bias is towards the middle of the forearm or towards the middle of the recent stimulus distribution. In Experiments 1 and 2, participants (n=12 and n=10) localized by pointing von Frey filaments applied to four locations on the dorsal forearm. Individually adjusted weak and strong stimuli (Experiment 1) or two levels of strong stimuli (Experiment 2) were presented in single sessions in random order...
January 9, 2019: Journal of Neurophysiology
Paulo Vianney Vilela-Rodrigues, Benjamin Auerbach, Richard J Salvi
Electrophysiological studies from humans suggest that the phantom sound of tinnitus is associated with abnormal thalamocortical neural oscillations. However, tinnitus models have seldom been tested in animal models where it is possible to simultaneously assess the neural oscillatory activity between the thalamus and auditory cortex. To explore this issue, we used multichannel electrodes to examine the oscillatory behavior of local field potentials recorded in the rat medial geniculate body (MBG) and primary auditory cortex (A1) before and after administering a dose of sodium salicylate (SS) that reliably induces tinnitus...
January 9, 2019: Journal of Neurophysiology
Keaton Proud, James B Heald, James Neilson Ingram, Jason P Gallivan, Daniel M Wolpert, J Randall Flanagan
Skillful manipulation requires forming and recalling memories of the dynamics of objects linking applied force to motion. It has been assumed that such memories are associated with entire objects. However, we often control different locations on an object, and these locations may be associated with different dynamics. We have previously demonstrated that multiple memories can be formed when participants are explicitly instructed to control different visual points marked on an object. A key question is whether this novel finding generalizes to more natural situations in which control points are implicitly defined by the task...
January 9, 2019: Journal of Neurophysiology
Timothy W Church, Jon T Brown, Neil V Marrion
Action potential firing in hippocampal pyramidal neurons is regulated by generation of an afterhyperpolarization (AHP). Three phases of AHP are recognised, with the fast AHP regulating action potential firing at the onset of a burst, and the medium and slow AHPs supressing action potential firing over 100s of milliseconds and seconds respectively. Activation of β-adrenergic receptors suppresses the slow AHP by a protein kinase A-dependent pathway. However, little is known regarding modulation of the medium AHP...
January 9, 2019: Journal of Neurophysiology
Reina Isayama, Michael Vesia, Gaayathiri Jegatheeswaran, Behzad Elahi, Carolyn A Gunraj, Lucilla Cardinali, Alessandro Farnè, Robert Chen
The rubber hand illusion (RHI) paradigm experimentally produces an illusion of rubber hand ownership and arm shift by simultaneously stroking a rubber hand in view and a participant's visually occluded hand. It involves visual, tactile and proprioceptive multisensory integration and activates multisensory areas in the brain including the posterior parietal cortex (PPC). Multisensory inputs are transformed into outputs for motor control in association areas such as PPC. A behavioural study reported decreased motor performance after RHI...
January 9, 2019: Journal of Neurophysiology
Alexander Paunov, Idan Asher Blank, Evelina Fedorenko
Communication requires the abilities to generate and interpret utterances and to infer the beliefs, desires, and goals of others ("Theory of Mind", ToM). These two abilities have been shown to dissociate: individuals with aphasia retain the ability to think about others' mental states; and individuals with autism are impaired in social reasoning, but their basic language processing is often intact. In line with this evidence from brain disorders, fMRI studies have shown that linguistic and ToM abilities recruit distinct sets of brain regions...
January 2, 2019: Journal of Neurophysiology
David D Kline, Sheng Wang, Diana L Kunze
CIH reduces afferent-evoked EPSCs but enhances basal spontaneous (s) and asynchronous (a) EPSCs in second-order nTS neurons, a major area for cardiorespiratory control. The net result is an increase in synaptic transmission. The mechanisms by which this occurs are unknown. The N-type calcium channel and transient receptor potential cation channel, TRPV1, play prominent roles in nTS sEPSCs and aEPSCs. The functional role of these channels in CIH-mediated afferent-evoked, sEPSC and aEPSC was tested in rat nTS slices following antagonist inhibition, and in mouse nTS slices which lack TRPV1...
January 2, 2019: Journal of Neurophysiology
Rajiv Ranganathan, Rani Gebara, Michael Andary, Jim Sylvain
Stroke often results in hemiparesis, leaving one side of the body affected relative to the other side. Prior research has shown that the affected arm has higher variability, however, the extent to which this variability can be modulated is unclear. Here we used a shared bimanual task to examine the degree to which participants could modulate the variability in the affected arm after stroke. Participants with chronic stroke (n = 11), and age-matched controls (n = 11) performed unimanual and bimanual reaching movements to move a cursor on a screen to different targets...
January 2, 2019: Journal of Neurophysiology
Nicholas Paul Holmes, Luigi Tamè, Paisley Beeching, Mary Medford, Mariyana Rakova, Alex Stuart, Silvia Zeni
Transcranial magnetic stimulation (TMS) over human primary somatosensory cortex (S1) does not produce immediate outputs. Researchers must therefore rely on indirect methods for TMS coil positioning. The 'gold standard' is to use individual functional and structural magnetic resonance imaging (MRI) data, but the majority of studies don't do this. The most common method to locate the hand area of S1 (S1-hand) is to move the coil posteriorly from the hand area of primary motor cortex (M1-hand). Yet, S1-hand is not directly posterior to M1-hand...
December 21, 2018: Journal of Neurophysiology
Karyna Yc, Luis Prado, Hugo Merchant
Dopamine, and specifically the D2-system, has been implicated in timing tasks where the absolute duration of individual time intervals is encoded discretely. Yet, the role of D2 during beat-perception and -entrainment remains largely unknown. In this type of timing, a beat is perceived as the pulse that marks equally spaced points in time and, once extracted, produces the tendency in humans to entrain or synchronize their movements to it. Hence, beat-based timing is crucial for musical execution. Here we investigated the effects of systemic injections of quinpirole (0...
December 21, 2018: Journal of Neurophysiology
Thomas McColgan, Paula T Kuokkanen, Catherine E Carr, Richard Kempter
Synaptic currents are frequently assumed to make a major contribution to the extracellular field potential (EFP). However, in any neuronal population, the explicit separation of synaptic sources from other contributions such as postsynaptic spikes remains a challenge. Here, we take advantage of the simple organization of the barn owl nucleus laminaris (NL) in the auditory brainstem to isolate synaptic currents through the iontophoretic application of the AMPA-receptor antagonist NBQX. Responses to auditory stimulation show that the temporal dynamics of the evoked synaptic contributions to the EFP are consistent with synaptic short-term depression (STD)...
December 21, 2018: Journal of Neurophysiology
Richard D Rabbitt
The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes...
December 19, 2018: Journal of Neurophysiology
Lavender A Otieno, George Mackenzie Opie, John G Semmler, Michael C Ridding, Simranjit K Sidhu
Fatiguing intermittent single-joint exercise causes an increase in corticospinal excitability and a decrease in intracortical inhibition when measured with peripherally recorded motor evoked potentials (MEPs) following transcranial magnetic stimulation (TMS). Combined TMS and electroencephalography (TMS-EEG) allows for more direct recording of cortical responses through the TMS-evoked potential (TEP). The aim of this study was to investigate the changes in the excitatory and inhibitory components of the TMS-evoked potential (TEP) during fatiguing single-joint exercise...
December 19, 2018: Journal of Neurophysiology
Zhaoran Zhang, Dagmar Sternad
This study examined how humans spontaneously merge a sequence of discrete actions into a rhythmic pattern even when periodicity is not required. Two experiments used a virtual throwing task, where subjects performed a long sequence of discrete throwing movements, aiming to hit a virtual target. In Experiment 1, subjects performed the task for 11 sessions. Even though there was no instruction to perform rhythmically, the variability of the inter-throw intervals decreased to a level comparable to that of synchronizing with a metronome; further, dwell times shortened or disappeared with practice...
December 19, 2018: Journal of Neurophysiology
Marie E Bellet, Joachim Bellet, Hendrikje Nienborg, Ziad M Hafed, Philipp Berens
Saccades are ballistic eye movements that rapidly shift gaze from one location of visual space to another. Detecting saccades in eye movement recordings is important not only for studying the neural mechanisms underlying sensory, motor, and cognitive processes, but also as a clinical and diagnostic tool. However, automatically detecting saccades can be difficult, particularly when such saccades are generated in coordination with other tracking eye movements, like smooth pursuits, or when the saccade amplitude is close to eye tracker noise levels, like with microsaccades...
December 19, 2018: Journal of Neurophysiology
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