PICs in motoneurons do not scale with the size of the animal: a possible mechanism for faster speed of muscle contraction in smaller species
In this study, we used in vivo preparations to record electrical properties of spinal motoneurons in deeply anesthetized adult mice and cats. We found that PICs do not scale with size, but instead are constant in their amplitudes across these species. This constancy, coupled with the threefold differences in electrical resistances, means that PICs contribute a threefold larger depolarization in the mouse than in the cat. As a consequence, motoneuronal firing rate sharply increases as animal size decreases. These differences in firing rates are likely essential in allowing different species to control muscles with widely di...
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Huh, S., Siripuram, R., Lee, R. H., Turkin, V. V., ONeill, D., Hamm, T. M., Heckman, C. J., Manuel, M. Tags: Research Articles Source Type: research
Task-dependent vestibular feedback responses in reaching
When reaching for an earth-fixed object during self-rotation, the motor system should appropriately integrate vestibular signals and sensory predictions to compensate for the intervening motion and its induced inertial forces. While it is well established that this integration occurs rapidly, it is unknown whether vestibular feedback is specifically processed dependent on the behavioral goal. Here, we studied whether vestibular signals evoke fixed responses with the aim to preserve the hand trajectory in space or are processed more flexibly, correcting trajectories only in task-relevant spatial dimensions. We used galvanic...
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Keyser, J., Medendorp, W. P., Selen, L. P. J. Tags: Research Articles Source Type: research
Moving slowly is hard for humans: limitations of dynamic primitives
Mounting evidence suggests that human motor control uses dynamic primitives, attractors of dynamic neuromechanical systems that require minimal central supervision. However, advantages for control may be offset by compromised versatility. Extending recent results showing that humans could not sustain discrete movements as duration decreased, this study tested whether smoothly rhythmic movements could be maintained as duration increased. Participants performed horizontal movements between two targets, paced by sounds with intervals that increased from 1 to 6 s by 200 ms per cycle and then decreased again. The instruction em...
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Park, S.-W., Marino, H., Charles, S. K., Sternad, D., Hogan, N. Tags: Research Articles Source Type: research
Density of available striatal dopamine receptors predicts trait impulsiveness during performance of an attention-demanding task
We present evidence uniquely consistent with the former interpretation, providing clarity to the nature of this brain-behavior relationship. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Anderson, B. A., Kuwabara, H., Wong, D. F., Courtney, S. M. Tags: Research Articles Source Type: research
Representation of individual forelimb muscles in primary motor cortex
In this study, we have investigated this question with respect to muscles of the arm and show consistent features of within-arm (intra-areal) somatotopic organization. For the first time we also show maps of how inhibitory output from motor cortex is organized. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Hudson, H. M., Park, M. C., Belhaj-Saïf, A., Cheney, P. D. Tags: Research Articles Source Type: research
Population activity statistics dissect subthreshold and spiking variability in V1
Response variability, as measured by fluctuating responses upon repeated performance of trials, is a major component of neural responses, and its characterization is key to interpret high dimensional population recordings. Response variability and covariability display predictable changes upon changes in stimulus and cognitive or behavioral state, providing an opportunity to test the predictive power of models of neural variability. Still, there is little agreement on which model to use as a building block for population-level analyses, and models of variability are often treated as a subject of choice. We investigate two ...
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Banyai, M., Koman, Z., Orban, G. Tags: Research Articles Source Type: research
Visual and presaccadic activity in area 8Ar of the macaque monkey lateral prefrontal cortex
Common trends observed in many visual and oculomotor-related cortical areas include retinotopically organized receptive and movement fields exhibiting a Gaussian shape and increasing size with eccentricity. These trends are demonstrated in the frontal eye fields, many visual areas, and the superior colliculus but have not been thoroughly characterized in prearcuate area 8Ar of the prefrontal cortex. This is important since area 8Ar, located anterior to the frontal eye fields, is more cytoarchitectonically similar to prefrontal areas than premotor areas. Here we recorded the responses of 166 neurons in area 8Ar of two male ...
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Bullock, K. R., Pieper, F., Sachs, A. J., Martinez-Trujillo, J. C. Tags: Research Articles Source Type: research
Impaired sweating responses to a passive whole body heat stress in individuals with multiple sclerosis
This study is the first to assess the reflex control of the thermoregulatory system in individuals living with multiple sclerosis (MS). The novel findings are twofold. First, attenuated increases in sweat rate in subjects with MS compared with healthy controls were observed in response to a moderate increase (0.8°C) in core temperature via passive whole body heat stress. Second, it appears the reflex control of the cutaneous vasculature is preserved in MS. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Allen, D. R., Huang, M., Parupia, I. M., Dubelko, A. R., Frohman, E. M., Davis, S. L. Tags: Research Articles Source Type: research
EEG oscillations: how are they modulated during different phases of repetitive movements?
Voluntary movements are planned through the relative timing between submovements of movement sequences as part of the motor program. Different movement phases are characterized by specific amplitude modulation of cortical oscillations. The latter represent neurophysiological correlates of specific synchronization or desynchronization of different neuronal groups. In this Neuro Forum, we review recent evidence regarding the temporal relation between neurophysiological correlates of different phases of a repetitive motor task using electroencephalography and source localization using individualized MRI. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Macerollo, A., Brown, M. J. N. Tags: Neuro Forum Source Type: research
Disharmony in neural oscillations
Cross-frequency phase coupling (PPC) may play an important role in neural processing and cognition. However, a new study unveils a statistical bias in how PPC is detected in neural recordings, questions prior evidence for PPC in hippocampus, and shows PPC tests are dramatically flawed by their confounds with oscillation harmonics. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - July 1, 2017 Category: Neurology Authors: Hyafil, A. Tags: Neuro Forum Source Type: research
New insights into vestibular-saccade interaction based on covert corrective saccades in patients with unilateral vestibular deficits
In response to passive high-acceleration head impulses, patients with low vestibulo-ocular reflex (VOR) gains often produce covert (executed while the head is still moving) corrective saccades in the direction of deficient slow phases. Here we examined 23 patients using passive, and 9 also active, head impulses with acute (< 10 days from onset) unilateral vestibular neuritis and low VOR gains. We found that when corrective saccades are larger than 10°, the slow-phase component of the VOR is inhibited, even though inhibition increases further the time to reacquire the fixation target. We also found that 1) saccades a...
Source: Journal of Neurophysiology - June 13, 2017 Category: Neurology Authors: Colagiorgio, P., Versino, M., Colnaghi, S., Quaglieri, S., Manfrin, M., Zamaro, E., Mantokoudis, G., Zee, D. S., Ramat, S. Tags: Research Articles Source Type: research
AMPA receptor-mediated rapid EPSCs in vestibular calyx afferents
In the vestibular periphery neurotransmission between hair cells and primary afferent nerves occurs via specialized ribbon synapses. Type I vestibular hair cells (HCIs) make synaptic contacts with calyx terminals, which enclose most of the HCI basolateral surface. To probe synaptic transmission, whole cell patch-clamp recordings were made from calyx afferent terminals isolated together with their mature HCIs from gerbil crista. Neurotransmitter release was measured as excitatory postsynaptic currents (EPSCs) in voltage clamp. Spontaneous EPSCs were classified as simple or complex. Simple events exhibited a rapid rise time ...
Source: Journal of Neurophysiology - June 13, 2017 Category: Neurology Authors: Kirk, M. E., Meredith, F. L., Benke, T. A., Rennie, K. J. Tags: Research Articles Source Type: research
Modeling the diversity of spontaneous and agonist-induced electrical activity in anterior pituitary corticotrophs
Pituitary corticotrophs fire action potentials spontaneously and in response to stimulation with corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP), and such electrical activity is critical for calcium signaling and calcium-dependent adrenocorticotropic hormone secretion. These cells typically fire tall, sharp action potentials when spontaneously active, but a variety of other spontaneous patterns have also been reported, including various modes of bursting. There is variability in reports of the fraction of corticotrophs that are electrically active, as well as their patterns of activity, and the sources...
Source: Journal of Neurophysiology - June 13, 2017 Category: Neurology Authors: Fletcher, P. A., Zemkova, H., Stojilkovic, S. S., Sherman, A. Tags: Research Articles Source Type: research
Coordination of pincer grasp and transport after mechanical perturbation of the index finger
In this study, we physically perturbed the index finger into extension during grasping closure on a minority of trials to test whether modifying the movement of one digit would affect the movement of the opposite digit, suggestive of an overarching coordinative process. Furthermore, we tested whether disruption of the grasp results in the modification of kinematic parameters of the transport. Our results showed that a continuous perturbation to the index finger affected wrist velocity but not lateral displacement. Moreover, we found that the typical flexion of the thumb observed in nonperturbed trials was delayed until the...
Source: Journal of Neurophysiology - June 6, 2017 Category: Neurology Authors: Schettino, L. F., Adamovich, S. V., Tunik, E. Tags: Research Articles Source Type: research
IL-1{beta}-induces NF-{kappa}B and upregulates microRNA-372 to inhibit spinal cord injury recovery
In this study we have shown that in cultured human neural stem cells (hNSC), IL-1β reduced the expression of both KIF3B (kinesin family member 3B) and NOSIP (nitric oxide synthase-interacting protein), two key modulators for restricting inflammation and promoting neuronal regeneration. The induction of microRNA-372 (miR-372) by IL-1β is specifically responsible for the inhibition of KIF3B and NOSIP. The 3'-untranslated regions (UTRs) of both KIF3B and NOSIP contain targeting sequences to miR-372 that directly inhibit their expression. Moreover, we found that the expression of miR-372 was stimulated in hNSC by IL-...
Source: Journal of Neurophysiology - June 6, 2017 Category: Neurology Authors: Zhou, W., Yuan, T., Gao, Y., Yin, P., Liu, W., Pan, C., Liu, Y., Yu, X. Tags: Research Articles Source Type: research
