scholarly journals The degree of acute descending control of spinal nociception in an area of primary hyperalgesia is dependent on the peripheral domain of afferent input

2014 ◽  
Vol 592 (16) ◽  
pp. 3611-3624 ◽  
Author(s):  
Robert A. R. Drake ◽  
Richard P. Hulse ◽  
Bridget M. Lumb ◽  
Lucy F. Donaldson
Keyword(s):  
Afferent Input ◽  
Primary Hyperalgesia ◽  
Peripheral Domain ◽  
Descending Control

The limits of human performance

2008 ◽  
Vol 44 ◽  
pp. 11-26 ◽  
Author(s):  
Ralph Beneke ◽  
Dieter Böning
Keyword(s):  
Human Performance ◽  
Safety Margin ◽  
Afferent Input ◽  
Metabolic Energy ◽  
Human Organism ◽  
Mechanical Resistance ◽  
As Doping ◽  
Gene And Protein Expression ◽  
Underlying Mechanisms ◽  
Biochemical Research

Human performance, defined by mechanical resistance and distance per time, includes human, task and environmental factors, all interrelated. It requires metabolic energy provided by anaerobic and aerobic metabolic energy sources. These sources have specific limitations in the capacity and rate to provide re-phosphorylation energy, which determines individual ratios of aerobic and anaerobic metabolic power and their sustainability. In healthy athletes, limits to provide and utilize metabolic energy are multifactorial, carefully matched and include a safety margin imposed in order to protect the integrity of the human organism under maximal effort. Perception of afferent input associated with effort leads to conscious or unconscious decisions to modulate or terminate performance; however, the underlying mechanisms of cerebral control are not fully understood. The idea to move borders of performance with the help of biochemicals is two millennia old. Biochemical findings resulted in highly effective substances widely used to increase performance in daily life, during preparation for sport events and during competition, but many of them must be considered as doping and therefore illegal. Supplements and food have ergogenic potential; however, numerous concepts are controversially discussed with respect to legality and particularly evidence in terms of usefulness and risks. The effect of evidence-based nutritional strategies on adaptations in terms of gene and protein expression that occur in skeletal muscle during and after exercise training sessions is widely unknown. Biochemical research is essential for better understanding of the basic mechanisms causing fatigue and the regulation of the dynamic adaptation to physical and mental training.

Prolongation of mechanical hyperalgesia by non nociceptive afferent input

2005 ◽  
Vol 32 (S 4) ◽  
Author(s):  
J Schattschneider ◽  
H.K Kim ◽  
J.M Chung ◽  
R Baron
Keyword(s):  
Afferent Input ◽  
Mechanical Hyperalgesia

A determination of excitability changes in dorsal spinocerebellar tract neurons from spike-train analysis

1977 ◽  
Vol 40 (3) ◽  
pp. 626-646 ◽  
Author(s):  
C. K. Knox ◽  
S. Kubota ◽  
R. E. Poppele
Keyword(s):  
Spike Train ◽  
Afferent Input ◽  
Complex Interactions ◽  
Group I ◽  
Long Latency ◽  
Cross Correlation Analysis ◽  
Output Spike ◽  
Type 3 ◽  
Stimulation Of

1. Responses of DSCT neurons to random electrical stimulation of peripheral nerves of the hindleg at group I intensity were studied using cross-correlation analysis of the output spike train with the stimulus. Three types of response were found: type 1 was due to monosynaptic activation of DSCT cells, type 2 resulted from inhibition of those cells, and type 3 was due to a long-latency excitation that was probably polysynaptic. 2. Most of the units studied responded to stimulation of both proximal and distal flexor and extensor nerves. The extensive convergence of afferent input on DSCT cells is much greater than has been observed previously, with type 2 and type 3 responses totaling 80% of the observed responses. We attribute this to the sensitivity of the analysis in detecting small changes in postsynaptic excitability. 3. The results of the study, particularly the derivation of postsynaptic excitability changes, generally confirm those of earlier work employing intracellular recording. 4. By varying stimulus rate and stimulus intensity in the group 1 range and simulating the resulting correlations, we conclude that excitability changes in DSCT cells are the net result of complex interactions involving excitation and inhibition. A summary of these findings is presented as a model for the minimum circuitry necessary to account for the observed behavior.

Visual and Tactile Information About Object-Curvature Control Fingertip Forces and Grasp Kinematics in Human Dexterous Manipulation

2000 ◽  
Vol 84 (6) ◽  
pp. 2984-2997 ◽  
Author(s):  
Per Jenmalm ◽  
Seth Dahlstedt ◽  
Roland S. Johansson
Keyword(s):  
Visual Processing ◽  
Visual Cues ◽  
Grip Force ◽  
Center Of Mass ◽  
Precision Grip ◽  
Sensory Information ◽  
Afferent Input ◽  
Dependent Manner ◽  
Tactile Sensibility ◽  
Grasp Stability

Most objects that we manipulate have curved surfaces. We have analyzed how subjects during a prototypical manipulatory task use visual and tactile sensory information for adapting fingertip actions to changes in object curvature. Subjects grasped an elongated object at one end using a precision grip and lifted it while instructed to keep it level. The principal load of the grasp was tangential torque due to the location of the center of mass of the object in relation to the horizontal grip axis joining the centers of the opposing grasp surfaces. The curvature strongly influenced the grip forces required to prevent rotational slips. Likewise the curvature influenced the rotational yield of the grasp that developed under the tangential torque load due to the viscoelastic properties of the fingertip pulps. Subjects scaled the grip forces parametrically with object curvature for grasp stability. Moreover in a curvature-dependent manner, subjects twisted the grasp around the grip axis by a radial flexion of the wrist to keep the desired object orientation despite the rotational yield. To adapt these fingertip actions to object curvature, subjects could use both vision and tactile sensibility integrated with predictive control. During combined blindfolding and digital anesthesia, however, the motor output failed to predict the consequences of the prevailing curvature. Subjects used vision to identify the curvature for efficient feedforward retrieval of grip force requirements before executing the motor commands. Digital anesthesia caused little impairment of grip force control when subjects had vision available, but the adaptation of the twist became delayed. Visual cues about the form of the grasp surface obtained before contact was used to scale the grip force, whereas the scaling of the twist depended on visual cues related to object movement. Thus subjects apparently relied on different visuomotor mechanisms for adaptation of grip force and grasp kinematics. In contrast, blindfolded subjects used tactile cues about the prevailing curvature obtained after contact with the object for feedforward adaptation of both grip force and twist. We conclude that humans use both vision and tactile sensibility for feedforward parametric adaptation of grip forces and grasp kinematics to object curvature. Normal control of the twist action, however, requires digital afferent input, and different visuomotor mechanisms support the control of the grasp twist and the grip force. This differential use of vision may have a bearing to the two-stream model of human visual processing.

Developmental Expression of Calcium-Binding Protein-Containing Neurons in Neocortical Transplants

1998 ◽  
Vol 7 (2) ◽  
pp. 121-129 ◽  
Author(s):  
Jeffrey M. Rosenstein ◽  
Newton S. More ◽  
Nina Mani ◽  
Janette M. Krum
Keyword(s):  
Oxidative Stress ◽  
Cortical Neurons ◽  
Calcium Binding ◽  
Binding Protein ◽  
Substantial Reduction ◽  
Qualitative Change ◽  
Afferent Input ◽  
Calcium Binding Protein ◽  
Developmental Expression ◽  
Parvalbumin Neurons

The present study examined the development of calcium binding protein-containing neurons in a timed series of fetal neocortical transplants. The immunoexpression of parvalbumin and calbindin, which are subpopulations of GABAergic neurons, have been widely studied in normal development and in disease and injury states. Because of their purported resistance to oxidative injury by their ability to buffer Ca++ influx, these neurons have been particularly studied following ischemia. Because it is likely that oxidative stress is associated with the grafting procedure, we sought to determine if these neurons displayed enhanced survival characteristics. Normally, parvalbumin and calbindin represent about 5-10% of cortical neurons. Within 2-4 wk after grafting the expression of both proteins increased markedly in that a relatively larger number of neurons (27% for parvalbumin) were immunopositive. This increase was transitory, however, and by 4 mo and beyond, confocal microscopic data showed a reduction of over 50% of parvalbumin (+) neurons and processes. Calbindin (+) processes showed a qualitative change in that they were smaller with less terminal branching. Electron microscopy confirmed a substantial reduction in parvalbumin synaptic contacts. Interestingly, in older grafts, remaining parvalbumin neurons were those that were strongly NSE (+) suggesting a link between normal metabolism and Ca++ buffering in grafted neurons. It is possible that in early grafts certain neuronal populations transiently upregulated calcium binding proteins as a defensive mechanism against Ca++ influx associated with oxidative stress. Over time, however, following physiological normalization within grafts, the calcium binding protein (+) neurons are diminished, possibly due to lack of appropriate afferent input to the interneuronal pool.

Calcitonin gene-related peptide receptors in rat trigeminal ganglion do not control spinal trigeminal activity

2012 ◽  
Vol 108 (2) ◽  
pp. 431-440 ◽  
Author(s):  
Oana Covasala ◽  
Sören L. Stirn ◽  
Stephanie Albrecht ◽  
Roberto De Col ◽  
Karl Messlinger
Keyword(s):  
Trigeminal Ganglion ◽  
Dura Mater ◽  
Calcitonin Gene Related Peptide ◽  
Afferent Input ◽  
Nitric Oxide Donor ◽  
Cgrp Receptor ◽  
Related Peptide ◽  
Trigeminal Neurons ◽  
Calcitonin Gene ◽  
Evoked Activity

Calcitonin gene-related peptide (CGRP) is regarded as a key mediator in the generation of primary headaches. CGRP receptor antagonists reduce migraine pain in clinical trials and spinal trigeminal activity in animal experiments. The site of CGRP receptor inhibition causing these effects is debated. Activation and inhibition of CGRP receptors in the trigeminal ganglion may influence the activity of trigeminal afferents and hence of spinal trigeminal neurons. In anesthetized rats extracellular activity was recorded from neurons with meningeal afferent input in the spinal trigeminal nucleus caudalis. Mechanical stimuli were applied at regular intervals to receptive fields located in the exposed cranial dura mater. α-CGRP (10−5 M), the CGRP receptor antagonist olcegepant (10−3 M), or vehicle was injected through the infraorbital canal into the trigeminal ganglion. The injection of volumes caused transient discharges, but vehicle, CGRP, or olcegepant injection was not followed by significant changes in ongoing or mechanically evoked activity. In animals pretreated intravenously with the nitric oxide donor glyceryl trinitrate (GTN, 250 μg/kg) the mechanically evoked activity decreased after injection of CGRP and increased after injection of olcegepant. In conclusion, the activity of spinal trigeminal neurons with meningeal afferent input is normally not controlled by CGRP receptor activation or inhibition in the trigeminal ganglion. CGRP receptors in the trigeminal ganglion may influence neuronal activity evoked by mechanical stimulation of meningeal afferents only after pretreatment with GTN. Since it has previously been shown that olcegepant applied to the cranial dura mater is ineffective, trigeminal activity driven by meningeal afferent input is more likely to be controlled by CGRP receptors located centrally to the trigeminal ganglion.

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