Removal of endogenous neuromodulators in a small motor network enhances responsiveness to neuromodulation
In this study we demonstrate that neurons of the crustacean stomatogastric ganglion generate apparent compensatory responses to loss of peptide neuromodulation, adding to the repertoire of mechanisms by which the stomatogastric nervous system can regulate and stabilize its own output. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - September 8, 2017 Category: Neurology Authors: Lett, K. M., Garcia, V. J., Temporal, S., Bucher, D., Schulz, D. J. Tags: Research Articles Source Type: research
Aging does not affect the intralimb coordination elicited by slip-like perturbation of different intensities
This study was aimed at verifying whether aging modifies intralimb coordination strategy during corrective responses elicited by unexpected slip-like perturbations delivered during steady walking on a treadmill. To this end, 10 young and 10 elderly subjects were asked to manage unexpected slippages of different intensities. We analyzed the planar covariation law of the lower limb segments, using the principal component analysis, to verify whether elevation angles of older subjects covaried along a plan before and after the perturbation. Results showed that segments related to the perturbed limbs of both younger and older p...
Source: Journal of Neurophysiology - September 5, 2017 Category: Neurology Authors: Aprigliano, F., Martelli, D., Tropea, P., Pasquini, G., Micera, S., Monaco, V. Tags: Research Articles Source Type: research
Impact of glutamatergic and serotonergic neurotransmission on diaphragm muscle activity after cervical spinal hemisection
In this study, we show that pharmacological inhibition of glutamatergic N-methyl-d-aspartate (NMDA) receptors blunts ipsilateral diaphragm activity post-SH. In contrast, pharmacological inhibition of serotonergic 5-HT2A receptors does not change diaphragm EMG activity post-SH. Our results suggest that NMDA receptor-mediated glutamatergic neurotransmission plays an important role in enhancing rhythmic respiratory-related diaphragm activity after spinal cord injury. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - September 5, 2017 Category: Neurology Authors: Mantilla, C. B., Gransee, H. M., Zhan, W.-Z., Sieck, G. C. Tags: Research Articles Source Type: research
Response preparation and execution during intentional bimanual pattern switching
During continuous bimanual coordination, in-phase (IP; 0° relative phase) and anti-phase (AP; 180° relative phase) patterns can be stably performed without practice. Paradigms in which participants are required to intentionally switch between these coordination patterns have been used to investigate the interaction between the performer’s intentions and intrinsic dynamics of the body’s preferred patterns. The current study examined the processes associated with switching preparation and execution through the use of a startling acoustic stimulus (SAS) as the switch stimulus. A SAS is known to involuntari...
Source: Journal of Neurophysiology - September 5, 2017 Category: Neurology Authors: Maslovat, D., Carter, M. J., Carlsen, A. N. Tags: Research Articles Source Type: research
Impaired visuomotor generalization by inconsistent attentional contexts
In daily life, people are constantly presented with situations in which they have to learn and acquire new motor skills in complex environments, where attention is often distracted by other events. Being able to generalize and perform the acquired motor action in different environments is a crucial part of visuomotor learning. The current study examined whether attentional distraction impairs generalization of visuomotor adaptation or whether consistent distraction can operate as an internal cue to facilitate generalization. Using a dual-task paradigm combining visuomotor rotational adaptation and an attention-demanding se...
Source: Journal of Neurophysiology - September 5, 2017 Category: Neurology Authors: Wang, T. S. L., Song, J.-H. Tags: Research Articles Source Type: research
Vibration over the larynx increases swallowing and cortical activation for swallowing
Sensory input can alter swallowing control in both the cortex and brainstem. Electrical stimulation of superior laryngeal nerve afferents increases reflexive swallowing in animals, with different frequencies optimally effective across species. Here we determined 1) if neck vibration overlying the larynx affected the fundamental frequency of the voice demonstrating penetration of vibration into the laryngeal tissues, and 2) if vibration, in comparison with sham, increased spontaneous swallowing and enhanced cortical hemodynamic responses to swallows in the swallowing network. A device with two motors, one over each thyroid ...
Source: Journal of Neurophysiology - September 5, 2017 Category: Neurology Authors: Mulheren, R. W., Ludlow, C. L. Tags: Research Articles Source Type: research
Fluorocitrate-mediated depolarization of astrocytes in the retrotrapezoid nucleus stimulates breathing
Evidence indicates that CO2/H+-evoked ATP released from retrotrapezoid nucleus (RTN) astrocytes modulates the activity of CO2-sensitive neurons. RTN astrocytes also sense H+ by inhibition of Kir4.1 channels; however, the relevance of this pH-sensitive current remains unclear since ATP release appears to involve CO2-dependent gating of connexin 26 hemichannels. Considering that depolarization mediated by H+ inhibition of Kir4.1 channels is expected to increase sodium bicarbonate cotransporter (NBC) conductance and favor Ca2+ influx via the sodium calcium exchanger (NCX), we hypothesize that depolarization in the presence of...
Source: Journal of Neurophysiology - September 5, 2017 Category: Neurology Authors: Sobrinho, C. R., Goncalves, C. M., Takakura, A. C., Mulkey, D. K., Moreira, T. S. Tags: Research Articles Source Type: research
Evidence of adaptations of locomotor neural drive in response to enhanced intermuscular connectivity between the triceps surae muscles of the rat
The aims of this study were to investigate changes 1) in the coordination of activation of the triceps surae muscle group, and 2) in muscle belly length of soleus (SO) and lateral gastrocnemius (LG) during locomotion (trotting) in response to increased stiffness of intermuscular connective tissues in the rat. We measured muscle activation and muscle belly lengths, as well as hindlimb kinematics, before and after an artificial enhancement of the connectivity between SO and LG muscles obtained by implanting a tissue-integrating surgical mesh at the muscles’ interface. We found that SO muscle activation decreased to 62%...
Source: Journal of Neurophysiology - September 5, 2017 Category: Neurology Authors: Bernabei, M., van Dieën, J. H., Maas, H. Tags: Research Articles Source Type: research
Contrasting speed-accuracy tradeoffs for eye and hand movements reveal the optimal nature of saccade kinematics
In contrast to hand movements, the existence of a neural representation of saccade kinematics is unclear. Saccade kinematics is typically thought to be specified by motor error/desired displacement and generated by brain stem circuits that are not penetrable to voluntary control. We studied the influence of instructed hand movement velocity on the kinematics of saccades executed without explicit instructions. When the hand movement was slow the saccade velocity decreased, independent of saccade amplitude. We leveraged this modulation of saccade velocity to study the optimality of saccades (in terms of velocity and endpoint...
Source: Journal of Neurophysiology - September 1, 2017 Category: Neurology Authors: Gopal, A., Jana, S., Murthy, A. Tags: Research Articles Source Type: research
The cerebellum does more than sensory prediction error-based learning in sensorimotor adaptation tasks
Individuals with damage to the cerebellum perform poorly in sensorimotor adaptation paradigms. This deficit has been attributed to impairment in sensory prediction error-based updating of an internal forward model, a form of implicit learning. These individuals can, however, successfully counter a perturbation when instructed with an explicit aiming strategy. This successful use of an instructed aiming strategy presents a paradox: In adaptation tasks, why do individuals with cerebellar damage not come up with an aiming solution on their own to compensate for their implicit learning deficit? To explore this question, we emp...
Source: Journal of Neurophysiology - September 1, 2017 Category: Neurology Authors: Butcher, P. A., Ivry, R. B., Kuo, S.-H., Rydz, D., Krakauer, J. W., Taylor, J. A. Tags: Research Articles Source Type: research
Effect of eye position during human visual-vestibular integration of heading perception
Visual and inertial stimuli provide heading discrimination cues. Integration of these multisensory stimuli has been demonstrated to depend on their relative reliability. However, the reference frame of visual stimuli is eye centered while inertia is head centered, and it remains unclear how these are reconciled with combined stimuli. Seven human subjects completed a heading discrimination task consisting of a 2-s translation with a peak velocity of 16 cm/s. Eye position was varied between 0° and ±25° left/right. Experiments were done with inertial motion, visual motion, or a combined visual-inertial motion. ...
Source: Journal of Neurophysiology - September 1, 2017 Category: Neurology Authors: Crane, B. T. Tags: Research Articles Source Type: research
The visual encoding of purely proprioceptive intermanual tasks is due to the need of transforming joint signals, not to their interhemispheric transfer
To perform goal-oriented hand movement, humans combine multiple sensory signals (e.g., vision and proprioception) that can be encoded in various reference frames (body centered and/or exo-centered). In a previous study (Tagliabue M, McIntyre J. PLoS One 8: e68438, 2013), we showed that, when aligning a hand to a remembered target orientation, the brain encodes both target and response in visual space when the target is sensed by one hand and the response is performed by the other, even though both are sensed only through proprioception. Here we ask whether such visual encoding is due 1) to the necessity of transferring sen...
Source: Journal of Neurophysiology - September 1, 2017 Category: Neurology Authors: Arnoux, L., Fromentin, S., Farotto, D., Beraneck, M., McIntyre, J., Tagliabue, M. Tags: Research Articles Source Type: research
Caffeine accelerates recovery from general anesthesia via multiple pathways
In this study, we show that caffeine is effective even at high levels of anesthetic. We also show that caffeine operates by both elevating intracellular cAMP levels and by blocking adenosine receptors. This complicated pharmacology makes caffeine especially effective in accelerating emergence from anesthesia. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - September 1, 2017 Category: Neurology Authors: Fong, R., Khokhar, S., Chowdhury, A. N., Xie, K. G., Wong, J. H.-Y., Fox, A. P., Xie, Z. Tags: Research Articles Source Type: research
Long-interval intracortical inhibition is asymmetric in young but not older adults
Aging is typically accompanied by a decline in manual dexterity and handedness; the dominant hand executes tasks of manual dexterity more quickly and accurately than the nondominant hand in younger adults, but this advantage typically declines with age. Age-related changes in intracortical inhibitory processes might play a role in the age-related decline in manual dexterity. Long-interval intracortical inhibition (LICI) is asymmetric in young adults, with more sensitive and more powerful LICI circuits in the dominant hemisphere than in the nondominant hemisphere. Here we investigated whether the hemispheric asymmetry in LI...
Source: Journal of Neurophysiology - September 1, 2017 Category: Neurology Authors: Vallence, A.- M., Smalley, E., Drummond, P. D., Hammond, G. R. Tags: Research Articles Source Type: research
Sensitivity of neurons in the middle temporal area of marmoset monkeys to random dot motion
We report the activity of neurons in marmoset MT in response to random-dot motion stimuli of varying coherence. The information carried by individual MT neurons was comparable to that of the macaque, and the maximum firing rates were a strong predictor of sensitivity. Our study provides key information regarding the neural basis of motion perception in the marmoset, a small primate species that is becoming increasingly popular as an experimental model. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - September 1, 2017 Category: Neurology Authors: Chaplin, T. A., Allitt, B. J., Hagan, M. A., Price, N. S. C., Rajan, R., Rosa, M. G. P., Lui, L. L. Tags: Research Articles Source Type: research
