Representing delayed force feedback as a combination of current and delayed states
We examined how participants cope with delayed forces that depend on their arm velocity 70 or 100 ms beforehand. After adaptation, participants applied opposing forces that revealed a partially correct representation of the perturbation using the current and the delayed information. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Avraham, G., Mawase, F., Karniel, A., Shmuelof, L., Donchin, O., Mussa-Ivaldi, F. A., Nisky, I. Tags: Research Articles Source Type: research
Group IV nociceptors develop axonal chemical sensitivity during neuritis and following treatment of the sciatic nerve with vinblastine
We have previously shown that nerve inflammation (neuritis) and transient vinblastine application lead to axonal mechanical sensitivity in nociceptors innervating deep structures. We also have shown that these treatments reduce axonal transport and have proposed that this leads to functional accumulation of mechanically sensitive channels in the affected part of the axons. Though informing the etiology of mechanically induced pain, axonal mechanical sensitivity does not address the common report of ongoing radiating pain during neuritis, which could be secondary to the provocation of axonal chemical sensitivity. We propose...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Govea, R. M., Barbe, M. F., Bove, G. M. Tags: Research Articles Source Type: research
Treadmill vs. overground walking: different response to physical interaction
Rehabilitation of human motor function is an issue of growing significance, and human-interactive robots offer promising potential to meet the need. For the lower extremity, however, robot-aided therapy has proven challenging. To inform effective approaches to robotic gait therapy, it is important to better understand unimpaired locomotor control: its sensitivity to different mechanical contexts and its response to perturbations. The present study evaluated the behavior of 14 healthy subjects who walked on a motorized treadmill and overground while wearing an exoskeletal ankle robot. Their response to a periodic series of ...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Ochoa, J., Sternad, D., Hogan, N. Tags: Research Articles Source Type: research
Different roles for inhibition in the rhythm-generating respiratory network
Unraveling the interplay of excitation and inhibition within rhythm-generating networks remains a fundamental issue in neuroscience. We use a biophysical model to investigate the different roles of local and long-range inhibition in the respiratory network, a key component of which is the pre-Bötzinger complex inspiratory microcircuit. Increasing inhibition within the microcircuit results in a limited number of out-of-phase neurons before rhythmicity and synchrony degenerate. Thus unstructured local inhibition is destabilizing and cannot support the generation of more than one rhythm. A two-phase rhythm requires re...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Harris, K. D., Dashevskiy, T., Mendoza, J., Garcia, A. J., Ramirez, J.-M., Shea-Brown, E. Tags: Research Articles Source Type: research
Prevention and reversal of latent sensitization of dorsal horn neurons by glial blockers in a model of low back pain in male rats
In an animal model of nonspecific low back pain, recordings from dorsal horn neurons were made to investigate the influence of glial cells in the central sensitization process. To induce a latent sensitization of the neurons, nerve growth factor (NGF) was injected into the multifidus muscle; the manifest sensitization to a second NGF injection 5 days later was used as a read-out. The sensitization manifested in increased resting activity and in an increased proportion of neurons responding to stimulation of deep somatic tissues. To block microglial activation, minocycline was continuously administered intrathecally startin...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Zhang, J., Mense, S., Treede, R.-D., Hoheisel, U. Tags: Research Articles Source Type: research
A reduced somatosensory gating response in individuals with multiple sclerosis is related to walking impairment
In this study, we examine the neural basis of somatosensory gating in patients with MS and healthy controls and assess the relationship between somatosensory gating and walking performance. We used magnetoencephalography to record neural responses to paired-pulse electrical stimulation applied to the right posterior tibial nerve. All participants also walked across a digital mat, which recorded their spatiotemporal gait kinematics. Our results showed the amplitude of the response to the second stimulation was sharply reduced only in controls, resulting in a significantly reduced somatosensory gating in the patients with MS...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Arpin, D. J., Gehringer, J. E., Wilson, T. W., Kurz, M. J. Tags: Research Articles Source Type: research
Inhibitory circuits of the mammalian main olfactory bulb
Synaptic inhibition critically influences sensory processing throughout the mammalian brain, including the main olfactory bulb (MOB), the first station of sensory processing in the olfactory system. Decades of research across numerous laboratories have established a central role for granule cells (GCs), the most abundant GABAergic interneuron type in the MOB, in the precise regulation of principal mitral and tufted cell (M/TC) firing rates and synchrony through lateral and recurrent inhibitory mechanisms. In addition to GCs, however, the MOB contains a vast diversity of other GABAergic interneuron types, and recent finding...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Burton, S. D. Tags: Reviews Source Type: research
Decoding sound level in the marmoset primary auditory cortex
Neurons that respond favorably to a particular sound level have been observed throughout the central auditory system, becoming steadily more common at higher processing areas. One theory about the role of these level-tuned or nonmonotonic neurons is the level-invariant encoding of sounds. To investigate this theory, we simulated various subpopulations of neurons by drawing from real primary auditory cortex (A1) neuron responses and surveyed their performance in forming different sound level representations. Pure nonmonotonic subpopulations did not provide the best level-invariant decoding; instead, mixtures of monotonic an...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Sun, W., Marongelli, E. N., Watkins, P. V., Barbour, D. L. Tags: Research Articles Source Type: research
Enhancement of phase-locking in rodents. I. An axonal recording study in gerbil
We presented stimuli as used in binaural studies to monaural neurons in the TB and studied their temporal coding. We found that general trends as have been described in the cat are present in gerbil, but with some important differences. Phase-locking to pure tones tends to be higher in TB axons and in neurons of the medial nucleus of the TB (MNTB) than in the auditory nerve for neurons with characteristic frequencies (CFs) below 1 kHz, but this enhancement is quantitatively more modest than in cat. Stronger enhancement is common when TB neurons are stimulated at low frequencies below CF. It is rare for TB neurons in gerbil...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Wei, L., Karino, S., Verschooten, E., Joris, P. X. Tags: Research Articles Source Type: research
Differential expression of long-term potentiation among identified inhibitory inputs to dopamine neurons
We describe a mapping of plasticity expression, mediated by different mechanisms, among three distinct GABA afferents to ventral tegmental area (VTA) dopamine neurons: the rostromedial tegmental nucleus, the nucleus accumbens, and the local GABA neurons within the VTA known to synapse on VTA dopamine neurons. This work is the first demonstration that discrete plasticity mechanisms recruit overlapping but different subsets of GABA inputs to VTA dopamine neurons. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Simmons, D. V., Petko, A. K., Paladini, C. A. Tags: Research Articles Source Type: research
Compensating for intersegmental dynamics across the shoulder, elbow, and wrist joints during feedforward and feedback control
Moving the arm is complicated by mechanical interactions that arise between limb segments. Such intersegmental dynamics cause torques applied at one joint to produce movement at multiple joints, and in turn, the only way to create single joint movement is by applying torques at multiple joints. We investigated whether the nervous system accounts for intersegmental limb dynamics across the shoulder, elbow, and wrist joints during self-initiated planar reaching and when countering external mechanical perturbations. Our first experiment tested whether the timing and amplitude of shoulder muscle activity account for interactio...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Maeda, R. S., Cluff, T., Gribble, P. L., Pruszynski, J. A. Tags: Research Articles Source Type: research
Basal tree complexity shapes functional pathways in the prefrontal cortex
While the morphology of basal dendritic trees in cortical pyramidal neurons varies, the functional implications of this diversity are just starting to emerge. In layer 5 pyramidal neurons of the prefrontal cortex, for example, increased basal tree complexity determines the recruitment of these neurons into functional circuits. Here, we use a modeling approach to investigate whether and how the morphology of the basal tree mediates the functional output of neurons. We implemented 57 basal tree morphologies of layer 5 prefrontal pyramidal neurons of the rat and identified morphological types that were characterized by differ...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Papoutsi, A., Kastellakis, G., Poirazi, P. Tags: Research Articles Source Type: research
Muscle disuse caused by botulinum toxin injection leads to increased central gain of the stretch reflex in the rat
Botulinum toxin (Btx) is used in children with cerebral palsy and in other neurological patients to diminish spasticity and reduce the risk of development of contractures. We investigated changes in the central gain of the stretch reflex circuitry in response to Btx injection in the triceps surae muscle in rats. Experiments were performed in 21 rats. Eight rats were a control group, and 13 rats were injected with 6 IU of Btx in the left triceps surae muscle. Two weeks after Btx injection, larger monosynaptic reflexes (MSR) were recorded from the left (injected) than the right (noninjected) L4 + L5 ventral roots following s...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Pingel, J., Hultborn, H., Näslund-Koch, L., Jensen, D. B., Wienecke, J., Nielsen, J. B. Tags: Research Articles Source Type: research
Novel channel-mediated choline transport in cholinergic neurons of the mouse retina
Choline uptake into the presynaptic terminal of cholinergic neurons is mediated by the high-affinity choline transporter and is essential for acetylcholine synthesis. In a previous study, we reported that P2X2 purinoceptors are selectively expressed in OFF-cholinergic amacrine cells of the mouse retina. Under specific conditions, P2X2 purinoceptors acquire permeability to large cations, such as N-methyl-d-glucamine, and therefore potentially could act as a noncanonical pathway for choline entry into neurons. We tested this hypothesis in OFF-cholinergic amacrine cells of the mouse retina. ATP-induced choline currents were o...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Ishii, T., Homma, K., Mano, A., Akagi, T., Shigematsu, Y., Shimoda, Y., Inoue, H., Kakinuma, Y., Kaneda, M. Tags: Research Articles Source Type: research
Restricted vision increases sensorimotor cortex involvement in human walking
This study aimed to determine whether there is electrocortical evidence of augmented participation of sensory brain areas in walking modulation during walking with eyes closed. Healthy subjects (n = 10) walked on a treadmill at 1 m/s while alternating 5 min of walking with the eyes open or closed while we recorded ground reaction forces (GRFs) and high-density scalp electroencephalography (EEG). We applied independent component analysis to parse EEG signals into maximally independent component (IC) processes and then computed equivalent current dipoles for each IC. We clustered cortical source ICs and analyzed event-relate...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Oliveira, A. S., Schlink, B. R., Hairston, W. D., König, P., Ferris, D. P. Tags: Research Articles Source Type: research
