Methodological considerations for a chronic neural interface with the cuneate nucleus of macaques
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 brain stem structures. Most previous investigations of CN response properties have been carried out in decerebrate or anesthetized animals, thereby eliminating the well-documen...
Source: Journal of Neurophysiology - December 5, 2017 Category: Neurology Authors: Suresh, A. K., Winberry, J. E., Versteeg, C., Chowdhury, R., Tomlinson, T., Rosenow, J. M., Miller, L. E., Bensmaia, S. J. Tags: Innovative Methodology Source Type: research
Improved methods for acrylic-free implants in nonhuman primates for neuroscience research
We describe a cost-effective set of procedures that maximizes the integration of headposts and recording cylinders with the animal’s tissues while reducing surgery time. Nine rhesus monkeys were implanted with titanium headposts, and one of these was also implanted with a recording chamber. In each case, a three-dimensional printed replica of the skull was created based on computerized tomography scans. The titanium feet of the headposts were shaped, and the skull thickness was measured preoperatively, reducing surgery time by up to 70%. The recording cylinder was manufactured to conform tightly to the skull, which w...
Source: Journal of Neurophysiology - December 5, 2017 Category: Neurology Authors: Overton, J. A., Cooke, D. F., Goldring, A. B., Lucero, S. A., Weatherford, C., Recanzone, G. H. Tags: Innovative Methodology Source Type: research
Corticospinal excitability of the biceps brachii is shoulder position dependent
In conclusion, CSE of the biceps brachii was dependent on shoulder position, and the pattern of change was altered within the state in which it was measured. The position-dependent changes in Mmax amplitude, EMG, and CSE itself all contribute to the overall change in CSE of the biceps brachii.
NEW & NOTEWORTHY We demonstrate that when the shoulder is placed into two common positions for determining elbow flexor force and activation, corticospinal excitability (CSE) of the biceps brachii is both shoulder position and state dependent. At rest, when the shoulder is flexed from 0° to 90°, supraspinal factors predom...
Source: Journal of Neurophysiology - December 5, 2017 Category: Neurology Authors: Collins, B. W., Cadigan, E. W. J., Stefanelli, L., Button, D. C. Tags: Research Articles Source Type: research
Social experience alters socially induced serotonergic fluctuations in the inferior colliculus
In this study, we tested how social experience influences the socially triggered serotonergic response in the inferior colliculus, an auditory midbrain region with an important role in vocalization processing. We used carbon fiber voltammetry to measure serotonin during social interactions of male mice (Mus musculus) from different social backgrounds: 4 weeks of grouped or individual housing. When paired with an unfamiliar male, both group-housed and individually housed males demonstrated elevations in serotonin; however, individually housed males exhibited socially triggered serotonergic responses with delayed time course...
Source: Journal of Neurophysiology - December 5, 2017 Category: Neurology Authors: Keesom, S. M., Sloss, B. G., Erbowor-Becksen, Z., Hurley, L. M. Tags: Research Articles Source Type: research
Evidence for the representation of movement kinematics in the discharge of F5 mirror neurons during the observation of transitive and intransitive actions
Mirror neurons (MirNs) are sensorimotor neurons that fire both when an animal performs a goal-directed action and when the same animal observes another agent performing the same or a similar transitive action. It has been claimed that the observation of intransitive actions does not activate MirNs in a monkey’s brain. Prompted by recent evidence indicating that the discharge of MirNs is modulated also by non-object-directed actions, we investigated thoroughly the efficacy of intransitive actions to trigger MirNs’ discharge. Using representational similarity analysis, we also studied whether the elements constit...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Papadourakis, V., Raos, V. Tags: Research Articles Source Type: research
Feature-coding transitions to conjunction-coding with progression through human visual cortex
Identifying an object and distinguishing it from similar items depends upon the ability to perceive its component parts as conjoined into a cohesive whole, but the brain mechanisms underlying this ability remain elusive. The ventral visual processing pathway in primates is organized hierarchically: Neuronal responses in early stages are sensitive to the manipulation of simple visual features, whereas neuronal responses in subsequent stages are tuned to increasingly complex stimulus attributes. It is widely assumed that feature-coding dominates in early visual cortex whereas later visual regions employ conjunction-coding in...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Cowell, R. A., Leger, K. R., Serences, J. T. Tags: Research Articles Source Type: research
Comparison of three models of saccade disconjugacy in strabismus
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. A number of control systems models have been developed to simulate th...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Walton, M. M. G., Mustari, M. J. Tags: Research Articles Source Type: research
Contribution of sensory feedback to plantar flexor muscle activation during push-off in adults with cerebral palsy
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. Seventeen adults with CP and 12 uninjured individuals participated. The participants walked on a treadmill while a robotized ankle-foot orthosis applied unload perturba...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Frisk, R. F., Jensen, P., Kirk, H., Bouyer, L. J., Lorentzen, J., Nielsen, J. B. Tags: Research Articles Source Type: research
Stability of hand force production. I. Hand level control variables and multifinger synergies
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. The "inverse piano" device was used to li...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Reschechtko, S., Latash, M. L. Tags: Research Articles Source Type: research
The effect of prior knowledge and intelligibility on the cortical entrainment response to speech
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. 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. To avoid these acoustic confounds, we used priming t...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Baltzell, L. S., Srinivasan, R., Richards, V. M. Tags: Research Articles Source Type: research
Extracellular H+ fluxes from tiger salamander Müller (glial) cells measured using self-referencing H+-selective microelectrodes
Self-referencing H+-selective electrodes were used to measure extracellular H+ fluxes from Müller (glial) cells isolated from the tiger salamander retina. A novel chamber enabled stable recordings using H+-selective microelectrodes in a self-referencing format using bicarbonate-based buffer solutions. A small basal H+ flux was observed from the end foot region of quiescent cells bathed in 24 mM bicarbonate-based solutions, and increasing extracellular potassium induced a dose-dependent increase in H+ flux. Barium at 6 mM also increased H+ flux. Potassium-induced extracellular acidifications were abolished when bica...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Kreitzer, M. A., Swygart, D., Osborn, M., Skinner, B., Heer, C., Kaufman, R., Williams, B., Shepherd, L., Caringal, H., Gongwer, M., Tchernookova, B. K., Malchow, R. P. Tags: Research Articles Source Type: research
Contribution of spiking activity in the primary auditory cortex to detection in noise
This study examines the contribution of A1 to detecting a sound that is presented with a noisy background. We found that population-level A1 activity, but not single neurons, could provide the evidence needed to make this perceptual decision. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Christison-Lagay, K. L., Bennur, S., Cohen, Y. E. Tags: Research Articles Source Type: research
The neural code for tactile roughness in the somatosensory nerves
Roughness is the most salient perceptual dimension of surface texture but has no well-defined physical basis. We seek to determine the neural determinants of tactile roughness in the somatosensory nerves. Specifically, we record the patterns of activation evoked in tactile nerve fibers of anesthetized Rhesus macaques to a large and diverse set of natural textures and assess what aspect of these patterns of activation can account for psychophysical judgments of roughness, obtained from human observers. We show that perceived roughness is determined by the variation in the population response, weighted by fiber type. That is...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Lieber, J. D., Xia, X., Weber, A. I., Bensmaia, S. J. Tags: Research Articles Source Type: research
GABA transporters regulate tonic and synaptic GABAA receptor-mediated currents in the suprachiasmatic nucleus neurons
GABA is a principal neurotransmitter in the hypothalamic suprachiasmatic nucleus (SCN) that contributes to intercellular communication between individual circadian oscillators within the SCN network and the stability and precision of the circadian rhythms. GABA transporters (GAT) regulate the extracellular GABA concentration and modulate GABAA receptor (GABAAR)-mediated currents. GABA transport inhibitors were applied to study how GABAAR-mediated currents depend on the expression and function of GAT. Nipecotic acid inhibits GABA transport and induced an inward tonic current in concentration-dependent manner during whole ce...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Moldavan, M., Cravetchi, O., Allen, C. N. Tags: Research Articles Source Type: research
The divisive normalization model of V1 neurons: a comprehensive comparison of physiological data and model predictions
The physiological responses of simple and complex cells in the primary visual cortex (V1) have been studied extensively and modeled at different levels. At the functional level, the divisive normalization model (DNM; Heeger DJ. Vis Neurosci 9: 181–197, 1992) has accounted for a wide range of single-cell recordings in terms of a combination of linear filtering, nonlinear rectification, and divisive normalization. We propose standardizing the formulation of the DNM and implementing it in software that takes static grayscale images as inputs and produces firing rate responses as outputs. We also review a comprehensive s...
Source: Journal of Neurophysiology - December 1, 2017 Category: Neurology Authors: Sawada, T., Petrov, A. A. Tags: Reviews Source Type: research
