The third-stimulus temporal discrimination threshold: focusing on the temporal processing of sensory input within primary somatosensory cortex
The objective of this study was to investigate whether the time interval required to discriminate between two stimuli varies according to the number of stimuli in the task. We used the third-stimulus temporal discrimination threshold (ThirdDT), defined as the shortest time interval at which an individual distinguishes a third stimulus following a pair of stimuli delivered at the STDT. The STDT and ThirdDT were assessed in 31 healthy subjects. In a subgroup of 10 subjects, we evaluated the effects of the stimuli intensity on the ThirdDT. In a subgroup of 16 subjects, we evaluated the effects of S1 continuous theta-burst sti...
Source: Journal of Neurophysiology - October 5, 2017 Category: Neurology Authors: Leodori, G., Formica, A., Zhu, X., Conte, A., Belvisi, D., Cruccu, G., Hallett, M., Berardelli, A. Tags: Research Articles Source Type: research
Intra- and intersegmental influences among central pattern generating networks in the walking system of the stick insect
To efficiently move around, animals need to coordinate their limbs. Proper, context-dependent coupling among the neural networks underlying leg movement is necessary for generating intersegmental coordination. In the slow-walking stick insect, local sensory information is very important for shaping coordination. However, central coupling mechanisms among segmental central pattern generators (CPGs) may also contribute to this. Here, we analyzed the interactions between contralateral networks that drive the depressor trochanteris muscle of the legs in both isolated and interconnected deafferented thoracic ganglia of the stic...
Source: Journal of Neurophysiology - October 5, 2017 Category: Neurology Authors: Mantziaris, C., Bockemühl, T., Holmes, P., Borgmann, A., Daun, S., Büschges, A. Tags: Research Articles Source Type: research
Orthodontic treatment-induced temporal alteration of jaw-opening reflex excitability
The impairment of orofacial motor function during orthodontic treatment needs to be addressed, because most orthodontic patients experience pain and motor excitability would be affected by pain. In the present study, the temporal alteration of the jaw-opening reflex excitability was investigated to determine if orthodontic treatment affects orofacial motor function. The excitability of jaw-opening reflex evoked by electrical stimulation on the gingiva and recorded bilaterally in the anterior digastric muscles was evaluated at 1 (D1), 3 (D3), and 7 days (D7) after orthodontic force application to the teeth of right side; mo...
Source: Journal of Neurophysiology - October 5, 2017 Category: Neurology Authors: Sasaki, A., Hasegawa, N., Adachi, K., Sakagami, H., Suda, N. Tags: Research Articles Source Type: research
Neuronal networks in the developing brain are adversely modulated by early psychosocial neglect
This study provides the first evidence of the adverse effects of early psychosocial neglect on the wiring of the developing brain. Given these networks' potentially significant role in various cognitive processes, including memory, learning, social communication, and language, these findings suggest that institutionalization in early life may profoundly impact the neural correlates underlying multiple cognitive domains, in ways that may not be fully reversible in the short term.
NEW & NOTEWORTHY This paper provides first evidence that early psychosocial neglect associated with institutional rearing profoundly affects t...
Source: Journal of Neurophysiology - October 5, 2017 Category: Neurology Authors: Stamoulis, C., Vanderwert, R. E., Zeanah, C. H., Fox, N. A., Nelson, C. A. Tags: Research Articles Source Type: research
Influence of pain on motor preparation in the human brain
The protective function of pain depends on appropriate motor responses to avoid injury and promote recovery. The preparation and execution of motor responses is thus an essential part of pain. However, it is not yet fully understood how pain and motor processes interact in the brain. Here we used electroencephalography to investigate the effects of pain on motor preparation in the human brain. Twenty healthy human participants performed a motor task in which they performed button presses to stop increasingly painful thermal stimuli when they became intolerable. In another condition, participants performed button presses wi...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Postorino, M., May, E. S., Nickel, M. M., Tiemann, L., Ploner, M. Tags: Research Articles Source Type: research
Theta-frequency selectivity in the somatic spike-triggered average of rat hippocampal pyramidal neurons is dependent on HCN channels
The ability to distill specific frequencies from complex spatiotemporal patterns of afferent inputs is a pivotal functional requirement for neurons residing in networks receiving frequency-multiplexed inputs. Although the expression of theta-frequency subthreshold resonance is established in hippocampal pyramidal neurons, it is not known if their spike initiation dynamics manifest spectral selectivity, or if their intrinsic properties are tuned to process gamma-frequency inputs. Here, we measured the spike-triggered average (STA) of rat hippocampal pyramidal neurons through electrophysiological recordings and quantified sp...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Das, A., Narayanan, R. Tags: Research Articles Source Type: research
A latent low-dimensional common input drives a pool of motor neurons: a probabilistic latent state-space model
Motor neurons appear to be activated with a common input signal that modulates the discharge activity of all neurons in the motor nucleus. It has proven difficult for neurophysiologists to quantify the variability in a common input signal, but characterization of such a signal may improve our understanding of how the activation signal varies across motor tasks. Contemporary methods of quantifying the common input to motor neurons rely on compiling discrete action potentials into continuous time series, assuming the motor pool acts as a linear filter, and requiring signals to be of sufficient duration for frequency analysis...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Feeney, D. F., Meyer, F. G., Noone, N., Enoka, R. M. Tags: Innovative Methodology Source Type: research
Sympathetic neural and hemodynamic responses to head-up tilt during isoosmotic and hyperosmotic hypovolemia
We hypothesized that muscle sympathetic nerve activity (MSNA) during head-up tilt (HUT) would be augmented during exercise-induced (hyperosmotic) dehydration but not isoosmotic dehydration via an oral diuretic. We studied 26 young healthy subjects (7 female, 19 male) divided into three groups: euhydrated (EUH, n = 7), previously exercised in 40°C while maintaining hydration; dehydrated (DEH, n = 10), previously exercised in 40°C during which ~3% of body weight was lost via sweat loss; and diuretic (DIUR, n = 9), a group that did not exercise but lost ~3% of body weight via diuresis (furosemide, 80 mg by mouth). We ...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Posch, A. M., Luippold, A. J., Mitchell, K. M., Bradbury, K. E., Kenefick, R. W., Cheuvront, S. N., Charkoudian, N. Tags: Research Articles Source Type: research
Dissecting patterns of preparatory activity in the frontal eye fields during pursuit target selection
We investigated the composition of preparatory activity of frontal eye field (FEF) neurons in monkeys performing a pursuit target selection task. In response to the orthogonal motion of a large and a small reward target, monkeys initiated pursuit biased toward the direction of large reward target motion. FEF neurons exhibited robust preparatory activity preceding movement initiation in this task. Preparatory activity consisted of two components, ramping activity that was constant across target selection conditions, and a flat offset in firing rates that signaled the target selection condition. Ramping activity accounted fo...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Raghavan, R. T., Joshua, M. Tags: Research Articles Source Type: research
Eupnea, tachypnea, and autoresuscitation in a closed-loop respiratory control model
How sensory information influences the dynamics of rhythm generation varies across systems, and general principles for understanding this aspect of motor control are lacking. Determining the origin of respiratory rhythm generation is challenging because the mechanisms in a central circuit considered in isolation may be different from those in the intact organism. We analyze a closed-loop respiratory control model incorporating a central pattern generator (CPG), the Butera-Rinzel-Smith (BRS) model, together with lung mechanics, oxygen handling, and chemosensory components. We show that 1) embedding the BRS model neuron in a...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Diekman, C. O., Thomas, P. J., Wilson, C. G. Tags: Research Articles Source Type: research
Measuring and quantifying skin sympathetic nervous system activity in humans
Development of the technique of microneurography has substantially increased our understanding of the function of the sympathetic nervous system (SNS) in health and in disease. The ability to directly record signals from peripheral autonomic nerves in conscious humans allows for qualitative and quantitative characterization of SNS responses to specific stimuli and over time. Furthermore, distinct neural outflow to muscle (MSNA) and skin (SSNA) can be delineated. However, there are limitations and caveats to the use of microneurography, measurement criteria, and signal analysis and interpretation. MSNA recordings have a lon...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Greaney, J. L., Kenney, W. L. Tags: Reviews Source Type: research
Spike-timing-dependent plasticity in lower-limb motoneurons after human spinal cord injury
In conclusion, PCMS elicits spike-timing-dependent changes at spinal synapses of lower-limb motoneurons in humans and has potential to improve lower-limb motor output following SCI.
NEW & NOTEWORTHY Approaches that aim to enhance corticospinal transmission to lower-limb muscles following spinal cord injury (SCI) are needed. We demonstrate that paired corticomotoneuronal stimulation (PCMS) can enhance plasticity at spinal synapses of lower-limb motoneurons in humans with and without SCI. We propose that PCMS has potential for improving motor output in leg muscles in individuals with damage to the corticospinal tract. (S...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Urbin, M. A., Ozdemir, R. A., Tazoe, T., Perez, M. A. Tags: Research Articles Source Type: research
Neural correlates for task switching in the macaque superior colliculus
Successful task switching requires a network of brain areas to select, maintain, implement, and execute the appropriate task. Although frontoparietal brain areas are thought to play a critical role in task switching by selecting and encoding task rules and exerting top-down control, how brain areas closer to the execution of tasks participate in task switching is unclear. The superior colliculus (SC) integrates information from various brain areas to generate saccades and is likely influenced by task switching. Here, we investigated switch costs in nonhuman primates and their neural correlates in the activity of SC saccade...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Chan, J. L., Koval, M. J., Johnston, K., Everling, S. Tags: Research Articles Source Type: research
Network activity influences the subthreshold and spiking visual responses of pyramidal neurons in the three-layer turtle cortex
A primary goal of systems neuroscience is to understand cortical function, typically by studying spontaneous and stimulus-modulated cortical activity. Mounting evidence suggests a strong and complex relationship exists between the ongoing and stimulus-modulated cortical state. To date, most work in this area has been based on spiking in populations of neurons. While advantageous in many respects, this approach is limited in scope: it records the activity of a minority of neurons and gives no direct indication of the underlying subthreshold dynamics. Membrane potential recordings can fill these gaps in our understanding, bu...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Wright, N. C., Wessel, R. Tags: Research Articles Source Type: research
Chronic pain alters spatiotemporal activation patterns of forearm muscle synergies during the development of grip force
This study used muscle synergy analysis to investigate multiple forearm muscles in individuals with chronic elbow pain during the development of grip force. Eleven individuals with chronic elbow pain and 11 healthy age-matched control subjects developed grip force to 15% and 30% of maximum voluntary contraction (MVC). Surface electromyography was obtained from six forearm muscles during force development before nonnegative matrix factorization was performed. The relationship between muscle synergies and standard clinical tests of elbow pain were examined by linear regression. During grip force development to 15% MVC the pa...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Manickaraj, N., Bisset, L. M., Devanaboyina, V. S. P. T., Kavanagh, J. J. Tags: Research Articles Source Type: research
