Cell type-specific changes in retinal ganglion cell function induced by rod death and cone reorganization in rats
This study provides novel and therapeutically relevant insights to retinal function following rod death but before cone death. To determine changes in retinal output, we used a large-scale multielectrode array to simultaneously record from hundreds of retinal ganglion cells (RGCs). These recordings of large-scale neural activity revealed that following the death of all rods, functionally distinct RGCs remain. However, the receptive field properties and spontaneous activity of these RGCs are altered in a cell type-specific manner. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - July 11, 2017 Category: Neurology Authors: Yu, W.-Q., Grzywacz, N. M., Lee, E.-J., Field, G. D. Tags: Research Articles Source Type: research
GABA and primary motor cortex inhibition in young and older adults: a multimodal reliability study
The effects of healthy aging on -aminobutyric acid (GABA) within primary motor cortex (M1) remain poorly understood. Studies have reported contrasting results, potentially due to limitations with the common assessment technique. The aim of the present study was to investigate the effect of healthy aging on M1 GABA concentration and neurotransmission using a multimodal approach. Fifteen young and sixteen older adults participated in this study. Magnetic resonance spectroscopy (MRS) was used to measure M1 GABA concentration. Single-pulse and threshold-tracking paired-pulse transcranial magnetic stimulation (TMS) protocols we...
Source: Journal of Neurophysiology - July 11, 2017 Category: Neurology Authors: Mooney, R. A., Cirillo, J., Byblow, W. D. Tags: Research Articles Source Type: research
Time compression of visual perception around microsaccades
Even during fixation, our eyes are in constant motion. For example, microsaccades are small (typically <1°) eye movements that occur 1~3 times/second. Despite their tiny and transient nature, our percept of visual space is compressed before microsaccades (Hafed ZM, Lovejoy LP, Krauzlis RJ. Eur J Neurosci 37: 1169–1181, 2013). As visual space and time are interconnected at both the physical and physiological levels, we asked whether microsaccades also affect the temporal aspects of visual perception. Here we demonstrate that the perceived interval between transient visual stimuli was compressed if accompanied b...
Source: Journal of Neurophysiology - July 11, 2017 Category: Neurology Authors: Yu, G., Yang, M., Yu, P., Dorris, M. C. Tags: Research Articles Source Type: research
Context effects on smooth pursuit and manual interception of a disappearing target
In our natural environment, we interact with moving objects that are surrounded by richly textured, dynamic visual contexts. Yet most laboratory studies on vision and movement show visual objects in front of uniform gray backgrounds. Context effects on eye movements have been widely studied, but it is less well known how visual contexts affect hand movements. Here we ask whether eye and hand movements integrate motion signals from target and context similarly or differently, and whether context effects on eye and hand change over time. We developed a track-intercept task requiring participants to track the initial launch o...
Source: Journal of Neurophysiology - July 7, 2017 Category: Neurology Authors: Kreyenmeier, P., Fooken, J., Spering, M. Tags: Research Articles Source Type: research
Loss and recovery of functional connectivity in cultured cortical networks exposed to hypoxia
In the core of a brain infarct, loss of neuronal function is followed by neuronal death within minutes. In an area surrounding the core (penumbra), some perfusion remains. Here, neurons initially remain structurally intact, but massive synaptic failure strongly reduces neural activity. Activity in the penumbra may eventually recover or further deteriorate toward massive cell death. Besides activity recovery, return of brain functioning requires restoration of connectivity. However, low activity has been shown to initiate compensatory mechanisms that affect network connectivity. We investigated the effect of transient hypox...
Source: Journal of Neurophysiology - July 7, 2017 Category: Neurology Authors: le Feber, J., Erkamp, N., van Putten, M. J. A. M., Hofmeijer, J. Tags: Research Articles Source Type: research
Implications of plan-based generalization in sensorimotor adaptation
Generalization is a fundamental aspect of behavior, allowing for the transfer of knowledge from one context to another. The details of this transfer are thought to reveal how the brain represents what it learns. Generalization has been a central focus in studies of sensorimotor adaptation, and its pattern has been well characterized: Learning of new dynamic and kinematic transformations in one region of space tapers off in a Gaussian-like fashion to neighboring untrained regions, echoing tuned population codes in the brain. In contrast to common allusions to generalization in cognitive science, generalization in visually g...
Source: Journal of Neurophysiology - July 7, 2017 Category: Neurology Authors: McDougle, S. D., Bond, K. M., Taylor, J. A. Tags: Research Articles Source Type: research
Prediction suppression and surprise enhancement in monkey inferotemporal cortex
Exposing monkeys, over the course of days and weeks, to pairs of images presented in fixed sequence, so that each leading image becomes a predictor for the corresponding trailing image, affects neuronal visual responsiveness in area TE. At the end of the training period, neurons respond relatively weakly to a trailing image when it appears in a trained sequence and, thus, confirms prediction, whereas they respond relatively strongly to the same image when it appears in an untrained sequence and, thus, violates prediction. This effect could arise from prediction suppression (reduced firing in response to the occurrence of a...
Source: Journal of Neurophysiology - July 7, 2017 Category: Neurology Authors: Ramachandran, S., Meyer, T., Olson, C. R. Tags: Research Articles Source Type: research
Increased neuromuscular consistency in gait and balance after partnered, dance-based rehabilitation in Parkinsons disease
Here we examined changes in muscle coordination associated with improved motor performance after partnered, dance-based rehabilitation in individuals with mild to moderate idiopathic Parkinson’s disease. Using motor module (a.k.a. muscle synergy) analysis, we identified changes in the modular control of overground walking and standing reactive balance that accompanied clinically meaningful improvements in behavioral measures of balance, gait, and disease symptoms after 3 wk of daily Adapted Tango classes. In contrast to previous studies that revealed a positive association between motor module number and motor perfor...
Source: Journal of Neurophysiology - July 7, 2017 Category: Neurology Authors: Allen, J. L., McKay, J. L., Sawers, A., Hackney, M. E., Ting, L. H. Tags: Research Articles Source Type: research
Effect of silhouetting and inversion on view invariance in the monkey inferotemporal cortex
We effortlessly recognize objects across changes in viewpoint, but we know relatively little about the features that underlie viewpoint invariance in the brain. Here, we set out to characterize how viewpoint invariance in monkey inferior temporal (IT) neurons is influenced by two image manipulations—silhouetting and inversion. Reducing an object into its silhouette removes internal detail, so this would reveal how much viewpoint invariance depends on the external contours. Inverting an object retains but rearranges features, so this would reveal how much viewpoint invariance depends on the arrangement and orientation...
Source: Journal of Neurophysiology - July 7, 2017 Category: Neurology Authors: Ratan Murty, N. A., Arun, S. R. Tags: Research Articles Source Type: research
Entrainment of visual steady-state responses is modulated by global spatial statistics
In this study, we used rhythmic entrainment source separation of scalp EEG to compare stimulus-driven phase alignment for distinct classes of visual inputs, including broadband spatial noise ensembles with varying second-order statistics, natural scenes, and narrowband sine-wave gratings delivered at a constant flicker frequency. The relative magnitude of visual entrainment was modulated by the global properties of the driving stimulus. Entrainment was strongest for pseudo-naturalistic broadband visual noise patterns in which luminance contrast is greatest at low spatial frequencies (a power spectrum slope characterized by...
Source: Journal of Neurophysiology - July 5, 2017 Category: Neurology Authors: Nguyen, T., Kuntzelman, K., Miskovic, V. Tags: Research Articles Source Type: research
Multisensory components of rapid motor responses to fingertip loading
Tactile and muscle afferents provide critical sensory information for grasp control, yet the contribution of each sensory system during online control has not been clearly identified. More precisely, it is unknown how these two sensory systems participate in online control of digit forces following perturbations to held objects. To address this issue, we investigated motor responses in the context of fingertip loading, which parallels the impact of perturbations to held objects on finger motion and fingerpad deformation, and characterized surface recordings of intrinsic (first dorsal interosseous, FDI) and extrinsic (flexo...
Source: Journal of Neurophysiology - July 5, 2017 Category: Neurology Authors: Crevecoeur, F., Barrea, A., Libouton, X., Thonnard, J.- L., Lefevre, P. Tags: Research Articles Source Type: research
Human primary somatosensory cortex is differentially involved in vibrotaction and nociception
The role of the primary somatosensory cortex (S1) in vibrotaction is well established. In contrast, its involvement in nociception is still debated. Here we test whether S1 is similarly involved in the processing of nonnociceptive and nociceptive somatosensory input in humans by comparing the aftereffects of high-definition transcranial direct current stimulation (HD-tDCS) of S1 on the event-related potentials (ERPs) elicited by nonnociceptive and nociceptive somatosensory stimuli delivered to the ipsilateral and contralateral hands. Cathodal HD-tDCS significantly affected the responses to nonnociceptive somatosensory stim...
Source: Journal of Neurophysiology - July 5, 2017 Category: Neurology Authors: Lenoir, C., Huang, G., Vandermeeren, Y., Hatem, S. M., Mouraux, A. Tags: Research Articles Source Type: research
Comparison of optomotor and optokinetic reflexes in mice
During animal locomotion or position adjustments, the visual system uses image stabilization reflexes to compensate for global shifts in the visual scene. These reflexes elicit compensatory head movements (optomotor response, OMR) in unrestrained animals or compensatory eye movements (optokinetic response, OKR) in head-fixed or unrestrained animals exposed to globally rotating striped patterns. In mice, OMR are relatively easy to observe and find broad use in the rapid evaluation of visual function. OKR determinations are more involved experimentally but yield more stereotypical, easily quantifiable results. The relative c...
Source: Journal of Neurophysiology - July 5, 2017 Category: Neurology Authors: Kretschmer, F., Tariq, M., Chatila, W., Wu, B., Badea, T. C. Tags: Research Articles Source Type: research
Neural mechanisms of oculomotor abnormalities in the infantile strabismus syndrome
Infantile strabismus is characterized by numerous visual and oculomotor abnormalities. Recently nonhuman primate models of infantile strabismus have been established, with characteristics that closely match those observed in human patients. This has made it possible to study the neural basis for visual and oculomotor symptoms in infantile strabismus. In this review, we consider the available evidence for neural abnormalities in structures related to oculomotor pathways ranging from visual cortex to oculomotor nuclei. These studies provide compelling evidence that a disturbance of binocular vision during a sensitive period ...
Source: Journal of Neurophysiology - July 5, 2017 Category: Neurology Authors: Walton, M. M. G., Pallus, A., Fleuriet, J., Mustari, M. J., Tarczy-Hornoch, K. Tags: Reviews Source Type: research
Recreational concentrations of alcohol enhance synaptic inhibition of cerebellar unipolar brush cells via pre- and postsynaptic mechanisms
Variation in cerebellar sensitivity to alcohol/ethanol (EtOH) is a heritable trait associated with alcohol use disorder in humans and high EtOH consumption in rodents, but the underlying mechanisms are poorly understood. A recently identified cellular substrate of cerebellar sensitivity to EtOH, the GABAergic system of cerebellar granule cells (GCs), shows divergent responses to EtOH paralleling EtOH consumption and motor impairment phenotype. Although GCs are the dominant afferent integrator in the cerebellum, such integration is shared by unipolar brush cells (UBCs) in vestibulocerebellar lobes. UBCs receive both GABAerg...
Source: Journal of Neurophysiology - July 5, 2017 Category: Neurology Authors: Richardson, B. D., Rossi, D. J. Tags: Research Articles Source Type: research
