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Journal of Neurophysiology

Nicholas Vaughan Swindale, Martin A Spacek
It is generally thought that apart from receptive field differences, such as preferred orientation and spatial frequency selectivity, primary visual cortex neurons are functionally similar to each other. However the genetic diversity of cortical neurons plus the existence of inputs additional to those required to explain known receptive field properties, might suggest otherwise. Here we report the existence of desynchronised states in anesthetised cat area 17 lasting up to 45 minutes, characterised by variable narrow-band local field potential (LFP) oscillations in the range 2 - 100 Hz and the absence of a synchronised 1/f frequency spectrum...
April 17, 2019: Journal of Neurophysiology
Julia Dlugaiczyk, Kathrin D Gensberger, Hans Straka
Galvanic vestibular stimulation (GVS) plays an important role in the quest to understand sensory signal processing in the vestibular system under normal and pathological conditions. It has become a highly relevant tool to probe neuronal computations and to assist in the differentiation and treatment of vestibular syndromes. Following its accidental discovery, GVS became a diagnostic tool that generates eye movements in the absence of head/body motion. With the possibility to record extra- and intracellular spikes, GVS became an indispensible method to activate or block the discharge in vestibular nerve fibers by cathodal and anodal currents, respectively...
April 17, 2019: Journal of Neurophysiology
Paul A Boakye, Vladimir Rancic, Kerri H Whitlock, Danielle Simmons, Frank M Longo, Klaus Ballanyi, Peter A Smith
Peripheral nerve injury elicits an enduring increase in the excitability of the spinal dorsal horn. This change, which contributes to the development of neuropathic pain, is a consequence of release and prolonged exposure of dorsal horn neurons to various neurotrophins and cytokines. We have shown in rats that nerve injury increases excitatory synaptic drive to excitatory neurons but decreases drive to inhibitory neurons. Both effects, which contribute to an increase in dorsal horn excitability, appear to be mediated by microglial-derived BDNF...
April 17, 2019: Journal of Neurophysiology
Peter J Boutros, Nicolas S Valentin, Kristin N Hageman, Chenkai Dai, Dale Roberts, Charles C Della Santina
Electrical stimulation of vestibular afferent neurons to partially restore semicircular canal sensation of head rotation and the stabilizing reflexes that sensation supports has potential to effectively treat individuals disabled by bilateral vestibular hypofunction. Ideally, a vestibular implant system using this approach would be integrated with a cochlear implant, which would provide clinicians with a means to simultaneously treat loss of both vestibular and auditory sensation. Despite obvious similarities, merging these technologies poses several challenges, including stimulus pulse timing errors that arise when a system must implement a pulse-frequency-modulation encoding scheme (as is used in vestibular implants to mimic normal vestibular nerve encoding of head movement) within fixed-rate continuous interleaved sampling (CIS) strategies used in cochlear implants...
April 17, 2019: Journal of Neurophysiology
Nicoletta Risi, Valay Shah, Leigh Ann A Mrotek, Maura Casadio, Robert A Scheidt
We examined vibrotactile stimulation as a form of supplemental limb state feedback to enhance planning and ongoing control of goal-directed movements. Subjects wore a two-dimensional vibrotactile display on their non-dominant arm while performing horizontal planar reaching with the dominant arm. The vibrotactile display provided feedback of hand position such that small hand displacements were more easily discriminable using vibrotactile feedback than with intrinsic proprioceptive feedback. When subjects relied solely on proprioception to capture visuospatial targets, performance was degraded by proprioceptive drift and an expansion of task space...
April 17, 2019: Journal of Neurophysiology
Yasuo Kawaguchi, Takeshi Otsuka, Mieko Morishima, Mika Ushimaru, Yoshiyuki Kubota
The cortex contains multiple neuron types with specific connectivity and functions. Recent progress has provided a better understanding of the interactions of these neuron types as well as their output organization particularly for the frontal cortex, with implications for the circuit mechanisms underlying cortical oscillations that have cognitive functions. Layer 5 (L5) pyramidal cells (PCs) in the frontal cortex comprise two major subtypes: crossed-corticostriatal (CCS) and corticopontine (CPn) cells. Functionally, CCS and CPn cells exhibit similar phase-dependent firing during gamma waves, but participate in two distinct subnetworks that are linked unidirectionally from CCS to CPn cells...
April 17, 2019: Journal of Neurophysiology
Jong-Hoon Nam, J W Grant, Michael H Rowe, Ellengene H Peterson
We review recent progress in using numerical models to relate utricular hair bundle and otoconial membrane structure to the functional requirements imposed by natural behavior in turtles. Section I reviews the evolution of experimental attempts to understand vestibular system function with emphasis on turtles, including data showing that accelerations occurring during natural head movements achieve higher magnitudes and frequencies than previously assumed. Section 2 reviews quantitative anatomical data documenting topographical variation in the structures underlying macromechanical and micromechanical responses of the turtle utricle to head movement: hair bundles, otoconial membrane (OM), and bundle-OM coupling...
April 17, 2019: Journal of Neurophysiology
Helen S Cohen
Although many studies have reported on tests of the vestibular system a valid and reliable, evidence-based screening battery for easy clinical use remains elusive. Many screening tests attempt to assess the vestibulo-ocular reflex. Therefore, head shaking, the Dix-Hallpike maneuver, the supine roll test and head impulse tests are discussed. Other tests address the spatial orientation functions of the vestibular system, such as the Bucket Test and the Fukuda Stepping test. Still other tests are based on the known correlates with balance skills, both static and dynamic, such as tandem walking and the modern variation of the Romberg test, the modified Clinical Test of Sensory Interaction and Balance...
April 17, 2019: Journal of Neurophysiology
Robijanto Soetedjo, Yoshiko Kojima, Albert F Fuchs
The neuronal substrate underlying the learning of a sophisticated task has been difficult to study. However, the advent of a behavioral paradigm that deceives the saccadic system into thinking it is making an error has allowed the mechanisms of the adaptation that corrects this error to be revealed in a primate. The neural elements that fashion the command signal for the generation of accurate saccades involve subcortical structures in the brainstem and cerebellum. Here we show that sites in both those structures also are involved with the gradual adaptation of saccade size, a form of motor learning...
April 17, 2019: Journal of Neurophysiology
Alejandra Barrera Curiel, Ryan J Colquhoun, Jesus Hernandez-Sarabia, Jason M DeFreitas
It is well known that muscle spindles have a monosynaptic, excitatory connection with alpha motoneurons. However, the influence of muscle spindles on human motor unit behavior during maximal efforts remains untested. It has also been shown that muscle spindle function, as assessed by peripheral reflexes, can be systematically manipulated with muscle vibration. Therefore, the purpose of this study was to analyze the effects of brief and prolonged vibration on maximal motor unit firing properties. A crossover design was utilized, where each of the 24 participants performed 1-3 maximal knee extensions under 3 separate conditions: 1) control; 2) brief vibration, applied during the contraction; and 3) after prolonged vibration, applied for ~20 min prior to the contraction...
April 10, 2019: Journal of Neurophysiology
Gregory Holst, William Andrew Stoy, Bo Yang, Ilya Kolb, Suhasa B Kodandaramaiah, Lu Li, Ulf Knoblich, Hongkui Zeng, Bilal Haider, Edward S Boyden, Craig R Forest
Patch clamping is the gold standard measurement technique for cell type characterization in vivo but it is low throughput, difficult to scale, and requires highly skilled operation. We developed an autonomous robot that can acquire multiple consecutive patch clamp recordings in vivo. In practice, 40 pipettes loaded into a carousel are sequentially filled and inserted into the brain, localized to a cell, used for patch clamping, and disposed. Automated visual stimulation and electrophysiology software enables functional cell type classification of whole cell patched cells, as we show for 37 cells in the anesthetized mouse in visual cortex (V1) L5...
April 10, 2019: Journal of Neurophysiology
Daniel Acker, Suzanne Paradis, Paul Miller
Our brains must maintain a representation of the world over a period of time much longer than the typical lifetime of the biological components producing that representation. For example, recent research suggests that dendritic spines in the adult mouse hippocampus are transient with an average lifetime of approximately 10 days. If this is true, and if turnover is equally likely for all spines, approximately 95-percent of excitatory synapses onto a particular neuron will turn over within 30 days; however, a neuron's receptive field can be relatively stable over this period...
April 10, 2019: Journal of Neurophysiology
Simon Merz, Julia Deller, Hauke S Meyerhoff, Charles Spence, Christian Frings
Representational momentum (RM) is the term used to describe a systematic mislocalization of dynamic stimuli, a forward shift, that is, an overestimation of the location of a stimulus along its anticipated trajectory. In the present study, we investigate the effect of velocity on tactile RM, as two distinct and contrasting predictions can be made, based on different theoretical accounts. According to classical accounts of RM, based on numerous visual and auditory RM studies, an increase of the forward shift with increasing target velocity is predicted...
April 10, 2019: Journal of Neurophysiology
Md Shoaibur Rahman, Jeffrey M Yau
Our ability to perceive and discriminate textures is based on the processing of high-frequency vibrations generated on the fingertip as it is scanned across a surface. Although much is known about the processing of vibration amplitude and frequency information when cutaneous stimulation is experienced at a single location on the body, how these stimulus features are processed when touch occurs at multiple locations is poorly understood. We evaluated participants ability to discriminate tactile cues on one hand while they ignored distractor cues experienced on their other hand...
April 10, 2019: Journal of Neurophysiology
Trevor Lee-Miller, Andrew M Gordon, Marco Santello
Dexterous object manipulation relies on the feedforward and feedback control of kinetics (forces) and kinematics (hand shaping and digit placement). Lifting objects with an uneven mass distribution involves the generation of compensatory moments at object lift-off to counter object torques. This is accomplished through the modulation and covariation of digit forces and placement, which has been shown to be a general feature of unimanual manipulation. These feedforward anticipatory processes occur prior to performance-specific feedback...
April 10, 2019: Journal of Neurophysiology
Serajul I Khan, Charles C Della Santina, Americo A Migliaccio
The role of the otoliths in mammals on the angular vestibulo-ocular reflex (VOR) has been difficult to determine because there is no surgical technique that can reliably ablate them without damaging the semicircular canals. The Otopetrin1 (Otop1) mouse lacks functioning otoliths due to failure to develop otoconia, but seems to have otherwise normal peripheral anatomy and neural circuitry. By using these animals we sought to determine the role of the otoliths in angular VOR baseline function and adaptation. In six Otop1 and six control littermates we measured: baseline ocular counter-tilt about the three primary axes in head coordinates; baseline horizontal (rotation about an Earth-vertical axis parallel to the dorsal-ventral axis) and vertical (rotation about an Earth-vertical axis parallel to the inter-aural axis) sinusoidal (0...
April 10, 2019: Journal of Neurophysiology
Azusa Hatta, Masayuki Kurose, Cara Sullivan, Keiichiro Okamoto, Noritaka Fujii, Kensuke Yamamura, Ian D Meng
Corneal cool cells are sensitive to the ocular fluid status of the corneal surface and may be responsible for the regulation of basal tear production. Previously, we have shown that dry eye, induced by lacrimal gland excision (LGE) in rats, sensitized corneal cool cells to the TRPM8 agonist menthol and to cool stimulation. In the present study, we examined the effect of dry eye on the sensitivity of cool cells to the TRPV1 agonist capsaicin. Single-unit recordings in the trigeminal ganglion were performed 7-10 days after LGE...
April 10, 2019: Journal of Neurophysiology
Cristian Cuadra, Ali Falaki, Robert L Sainburg, Fabrice R Sarlegna, Mark L Latash
We tested finger force interdependence and multi-finger force-stabilizing synergies in a patient with large-fiber peripheral neuropathy ("deafferented person"). The subject performed a range of tasks involving accurate force production with one finger and with four fingers. In one-finger tasks, non-task fingers showed unintentional force production (enslaving) with an atypical pattern: Very large indices for the lateral (index and little) fingers and relatively small indices for the central (middle and ring) fingers...
April 10, 2019: Journal of Neurophysiology
Bryan K Ward, Dale Roberts, Jorge Otero-Millan, David S Zee
For many years, people working near strong static magnetic fields of magnetic resonance imaging (MRI) machines have reported dizziness and sensations of vertigo. The discovery a decade ago that a sustained nystagmus can be observed in all humans with an intact labyrinth inside MRI machines led to a possible mechanism: a Lorentz force occurring in the labyrinth from the interactions of normal inner ear ionic currents and the strong static magnetic fields of the MRI machine. Inside an MRI, the Lorentz force acts to induce a constant deflection of the semicircular canal cupula of the superior and lateral semicircular canals...
April 10, 2019: Journal of Neurophysiology
Serajul I Khan, Charles C Della Santina, Americo A Migliaccio
The role of the otoliths in mammals on the normal angular vestibulo-ocular reflex (VOR) was characterised in an accompanying study based on the Otopetrin1 (Otop1) mouse, which lacks functioning otoliths due to failure to develop otoconia but seems to have otherwise normal peripheral anatomy and neural circuitry. That study showed that otoliths do not contribute to the normal horizontal (rotation about Earth-vertical axis parallel to dorso-ventral axis) and vertical angular VOR (rotation about Earth-vertical axis parallel to inter-aural axis), but do affect gravity context-specific VOR adaptation...
April 10, 2019: Journal of Neurophysiology
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