The firing characteristics of foot sole cutaneous mechanoreceptor afferents in response to vibration stimuli
Single unit microneurography was used to record the firing characteristics of the four classes of foot sole cutaneous afferents [fast and slowly adapting type I and II (FAI, FAII, SAI, and SAII)] in response to sinusoidal vibratory stimuli. Frequency (3–250 Hz) and amplitude (0.001–2 mm) combinations were applied to afferent receptive fields through a 6-mm diameter probe. The impulses per cycle, defined as the number of action potentials evoked per vibration sine wave, were measured over 1 s of vibration at each frequency-amplitude combination tested. Afferent entrainment threshold (lowest amplitude at which an...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Strzalkowski, N. D. J., Ali, R. A., Bent, L. R. Tags: Research Articles Source Type: research
Approaching threatening stimuli cause an expansion of defensive peripersonal space
When sudden environmental stimuli signaling threat occur in the portion of space surrounding the body (defensive peripersonal space), defensive responses are enhanced. Recently Bisio et al. (Bisio A, Garbarini F, Biggio M, Fossataro C, Ruggeri P, Bove M. J Neurosci 37: 2415–2424, 2017) showed that a marker of defensive peripersonal space, the defensive hand-blink reflex, is modulated by the motion of the eliciting threatening stimulus. These results can be parsimoniously explained by the continuous monitoring of environmental threats, resulting in an expansion of defensive peripersonal space when threatening stimuli ...
Source: Journal of Neurophysiology - October 1, 2017 Category: Neurology Authors: Bufacchi, R. J. Tags: Neuro Forum Source Type: research
Emergent cortical circuit dynamics contain dense, interwoven ensembles of spike sequences
Temporal codes are theoretically powerful encoding schemes, but their precise form in the neocortex remains unknown in part because of the large number of possible codes and the difficulty in disambiguating informative spikes from statistical noise. A biologically plausible and computationally powerful temporal coding scheme is the Hebbian assembly phase sequence (APS), which predicts reliable propagation of spikes between functionally related assemblies of neurons. Here, we sought to measure the inherent capacity of neocortical networks to produce reliable sequences of spikes, as would be predicted by an APS code. To reco...
Source: Journal of Neurophysiology - September 14, 2017 Category: Neurology Authors: Dechery, J. B., MacLean, J. N. Tags: Research Articles Source Type: research
Spatially tuned normalization explains attention modulation variance within neurons
We present an equal-maximum-suppression spatially tuned normalization model that explains this covariance both across and within neurons: each stimulus generates equally strong suppression of its own excitatory drive, but its suppression of distant stimuli is typically less. This new model specifies how the tuned normalization associated with each stimulus location varies across space both within and across neurons, changing our understanding of the normalization mechanism and how attention modulations depend on this mechanism.
NEW & NOTEWORTHY Tuned normalization studies have demonstrated that the variance in attentio...
Source: Journal of Neurophysiology - September 14, 2017 Category: Neurology Authors: Ni, A. M., Maunsell, J. H. R. Tags: Research Articles Source Type: research
Climbing fibers predict movement kinematics and performance errors
This article demonstrates that complex spike (CS) discharge of cerebellar Purkinje cells encodes multiple parameters of movement, including motor errors and kinematics. The CS firing is not driven by error or kinematic events; instead it provides a linear representation of each parameter. In contrast with the view that CSs carry feedback signals, the CSs are predominantly predictive of upcoming position errors and kinematics. Therefore, climbing fibers carry multiple and predictive signals for online motor control. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - September 14, 2017 Category: Neurology Authors: Streng, M. L., Popa, L. S., Ebner, T. J. Tags: Research Articles Source Type: research
Envelope contributions to the representation of interaural time difference in the forebrain of barn owls
Birds and mammals use the interaural time difference (ITD) for azimuthal sound localization. While barn owls can use the ITD of the stimulus carrier frequency over nearly their entire hearing range, mammals have to utilize the ITD of the stimulus envelope to extend the upper frequency limit of ITD-based sound localization. ITD is computed and processed in a dedicated neural circuit that consists of two pathways. In the barn owl, ITD representation is more complex in the forebrain than in the midbrain pathway because of the combination of two inputs that represent different ITDs. We speculated that one of the two inputs inc...
Source: Journal of Neurophysiology - September 14, 2017 Category: Neurology Authors: Tellers, P., Lehmann, J., Führ, H., Wagner, H. Tags: Research Articles Source Type: research
Use of the Aplysia feeding network to study repetition priming of an episodic behavior
Many central pattern generator (CPG)-mediated behaviors are episodic, meaning that they are not continuously ongoing; instead, there are pauses between bouts of activity. This raises an interesting possibility, that the neural networks that mediate these behaviors are not operating under "steady-state" conditions; i.e., there could be dynamic changes in motor activity as it stops and starts. Research in the feeding system of the mollusk Aplysia californica has demonstrated that this can be the case. After a pause, initial food grasping responses are relatively weak. With repetition, however, responses strengthen. In this r...
Source: Journal of Neurophysiology - September 14, 2017 Category: Neurology Authors: Cropper, E. C., Jing, J., Perkins, M. H., Weiss, K. R. Tags: Reviews Source Type: research
Motor learning in a complex balance task and associated neuroplasticity: a comparison between endurance athletes and nonathletes
Studies suggested that motor expertise is associated with functional and structural brain alterations, which positively affect sensorimotor performance and learning capabilities. The purpose of the present study was to unravel differences in motor skill learning and associated functional neuroplasticity between endurance athletes (EA) and nonathletes (NA). For this purpose, participants had to perform a multimodal balance task (MBT) training on 2 sessions, which were separated by 1 wk. Before and after MBT training, a static balance task (SBT) had to be performed. MBT-induced functional neuroplasticity and neuromuscular al...
Source: Journal of Neurophysiology - September 14, 2017 Category: Neurology Authors: Seidel, O., Carius, D., Kenville, R., Ragert, P. Tags: Research Articles Source Type: research
Perspectives on classical controversies about the motor cortex
Primary motor cortex has been studied for more than a century, yet a consensus on its functional contribution to movement control is still out of reach. In particular, there remains controversy as to the level of control produced by motor cortex ("low-level" movement dynamics vs. "high-level" movement kinematics) and the role of sensory feedback. In this review, we present different perspectives on the two following questions: What does activity in motor cortex reflect? and How do planned motor commands interact with incoming sensory feedback during movement? The four authors each present their independent views on how the...
Source: Journal of Neurophysiology - September 14, 2017 Category: Neurology Authors: Omrani, M., Kaufman, M. T., Hatsopoulos, N. G., Cheney, P. D. Tags: Reviews Source Type: research
The neural mechanisms able to predict future emotion regulation decisions
Emotion regulation is crucial in maintaining healthy psychological well-being, and its dysregulation is often linked to a range of neuropsychiatric disorders including depression. The neurobiological underpinnings of cognitive reappraisal, an emotion regulation strategy, have been shown to include the amygdala and regions of the prefrontal cortex. A novel study by Doré, Weber, and Ochsner (J Neurosci 37: 2580–2588, 2017) has demonstrated that neural activity in these regions during uninstructed visualization of affective stimuli can successfully predict which individuals are more likely to subsequently employ ...
Source: Journal of Neurophysiology - September 14, 2017 Category: Neurology Authors: Bendall, R. C. A. Tags: Neuro Forum Source Type: research
Differential contributions to the interception of occluded ballistic trajectories by the temporoparietal junction, area hMT/V5+, and the intraparietal cortex
The ability to catch objects when transiently occluded from view suggests their motion can be extrapolated. Intraparietal cortex (IPS) plays a major role in this process along with other brain structures, depending on the task. For example, interception of objects under Earth’s gravity effects may depend on time-to-contact predictions derived from integration of visual signals processed by hMT/V5+ with a priori knowledge of gravity residing in the temporoparietal junction (TPJ). To investigate this issue further, we disrupted TPJ, hMT/V5+, and IPS activities with transcranial magnetic stimulation (TMS) while subjects...
Source: Journal of Neurophysiology - September 8, 2017 Category: Neurology Authors: Delle Monache, S., Lacquaniti, F., Bosco, G. Tags: Research Articles Source Type: research
A novel paraplegia model in awake behaving macaques
Lower limb paralysis from spinal cord injury (SCI) or neurological disease carries a poor prognosis for recovery and remains a large societal burden. Neurophysiological and neuroprosthetic research have the potential to improve quality of life for these patients; however, the lack of an ethical and sustainable nonhuman primate model for paraplegia hinders their advancement. Therefore, our multidisciplinary team developed a way to induce temporary paralysis in awake behaving macaques by creating a fully implantable lumbar epidural catheter-subcutaneous port system that enables easy and reliable targeted drug delivery for se...
Source: Journal of Neurophysiology - September 8, 2017 Category: Neurology Authors: Krucoff, M. O., Zhuang, K., MacLeod, D., Yin, A., Byun, Y. W., Manson, R. J., Turner, D. A., Oliveira, L., Lebedev, M. A. Tags: Innovative Methodology Source Type: research
Fast voltage-sensitive dye imaging of excitatory and inhibitory synaptic transmission in the rat granular retrosplenial cortex
In conclusion, ATN inputs are processed differently in coronal and horizontal planes of the GRS and then conveyed to other cortical areas. In both planes, GRS superficial layers play an important role in signal propagation, which suggests that superficial neuronal cascade is crucial in the integration of multiple information sources.
NEW & NOTEWORTHY Superficial neurons in the rat granular retrosplenial cortex (GRS) show distinctive late-spiking (LS) firing property. However, little is known about spatiotemporal dynamics of signal transduction in the GRS. We demonstrated LS neuron network relaying thalamic inputs to de...
Source: Journal of Neurophysiology - September 8, 2017 Category: Neurology Authors: Nixima, K., Okanoya, K., Ichinohe, N., Kurotani, T. Tags: Research Articles Source Type: research
Intermuscular coherence reflects functional coordination
Coherence analysis has the ability to identify the presence of common descending drive shared by motor unit pools and reveals its spectral properties. However, the link between spectral properties of shared neural drive and functional interactions among muscles remains unclear. We assessed shared neural drive between muscles of the thumb and index finger while participants executed two mechanically distinct precision pinch tasks, each requiring distinct functional coordination among muscles. We found that shared neural drive was systematically reduced or enhanced at specific frequencies of interest (~10 and ~40 Hz). While ...
Source: Journal of Neurophysiology - September 8, 2017 Category: Neurology Authors: Laine, C. M., Valero-Cuevas, F. J. Tags: Research Articles Source Type: research
Discrimination of curvature from motion during smooth pursuit eye movements and fixation
Smooth pursuit and motion perception have mainly been investigated with stimuli moving along linear trajectories. Here we studied the quality of pursuit movements to curved motion trajectories in human observers and examined whether the pursuit responses would be sensitive enough to discriminate various degrees of curvature. In a two-interval forced-choice task subjects pursued a Gaussian blob moving along a curved trajectory and then indicated in which interval the curve was flatter. We also measured discrimination thresholds for the same curvatures during fixation. Motion curvature had some specific effects on smooth pur...
Source: Journal of Neurophysiology - September 8, 2017 Category: Neurology Authors: Ross, N. M., Goettker, A., Schütz, A. C., Braun, D. I., Gegenfurtner, K. R. Tags: Research Articles Source Type: research
