Offset analgesia evoked by non-contact thermal stimulator

2010 ◽  
Vol 1 (3) ◽  
pp. 169-170
Author(s):  
K.S. Frahm ◽  
O.K. Andersen ◽  
L. Arendt-Nielsen ◽  
C.D. Mørch
Keyword(s):  
Pain Intensity ◽  
Infrared Camera ◽  
Glabrous Skin ◽  
Contact Heat ◽  
Hairy Skin ◽  
High Penetration ◽  
Pain Ratings ◽  
The Subject ◽  
Thermal Stimulator ◽  
Palm Of The Hand

AbstractObjectiveThe objective of this study was to test if offset analgesia could be evoked using a noncontact thermal stimulator. Offset analgesia [J. Neurophysiol. 87:2205–2208, 2002] is defined as an unproportionally large decrease in pain intensity following a slight decrease in stimulation intensity. The importance of differences in thermal properties between human hairy and glabrous skin was investigated.MethodsA 20W diode laser (970 nm) was used for the thermal stimulation. A fast (50 images/s) infrared camera measured the skin temperature and a temperature controlled feedback control loop adjusted the laser power. 8 subjects participated in this study. Stimulations were applied on the dorsum side and in the palm of the hand. Subjects were instructed to continuously rate the pain intensity. First the subject was stimulated using both a rising 35–45 °C staircase and a decreasing 45–35 °C staircase in both skin types; each staircase step was 1 °C and lasted for 15 s. Offset analgesia was tested by stimulating the hairy skin on the dorsum of the hand using two sequential temperature plateaus (48–48 °C, 48–49 °C, 49–48 °C and 49–49 °C). Each plateau was held for 5 s.ResultsFor the staircase stimulations identical surface temperatures were perceived significantly higher in glabrous than in hairy skin (p < 0.001). The offset analgesia test showed that a decrease in temperature from 49 to 48 °C evoked a drop in the pain rating which was significantly lower than observed during a 48–48 °C stimulation (p < 0.001) indicating offset analgesia.ConclusionA non-contact thermal stimulator is able to evoke offset analgesia. Furthermore, it was noted that a high penetration laser causes higher pain ratings in glabrous skin than in hairy skin—a relationship which is opposite to low penetration lasers (CO2 laser) and contact heat stimulation.

scholarly journals Specialized mechanoreceptor systems in rodent glabrous skin

2018 ◽  
Author(s):  
Jan Walcher ◽  
Julia Ojeda-Alonso ◽  
Julia Haseleu ◽  
Maria K. Oosthuizen ◽  
Ashlee H. Rowe ◽  
...  
Keyword(s):  
Small Group ◽  
Rodent Species ◽  
Glabrous Skin ◽  
Skin Area ◽  
Mechanical Stimuli ◽  
Orientation Sensitivity ◽  
Hairy Skin ◽  
Physiological Properties ◽  
Sensory Fibers ◽  
Very High

AbstractRodents use their forepaws to actively interact with their tactile environment. Studies on the physiology and anatomy of glabrous skin that makes up the majority of the forepaw are almost non-existent in the mouse. Here we developed a preparation to record from single sensory fibers of the forepaw and compared anatomical and physiological receptor properties to those of the hind paw glabrous and hairy skin. We found that the mouse forepaw skin is equipped with a very high density of mechanoreceptors; >3 fold more than hind paw glabrous skin. In addition, rapidly adapting mechanoreceptors that innervate Meissner’s corpuscles of the forepaw were several-fold more sensitive to slowly moving mechanical stimuli compared to their counterparts in the hind paw glabrous skin. All other mechanoreceptors types as well as myelinated nociceptors had physiological properties that were invariant regardless of which skin area they occupied. We discovered a novel D-hair receptor innervating a small group of hairs in the middle of the hind paw glabrous skin in mice. Glabrous D-hair receptors were direction sensitive albeit with an orientation sensitivity opposite to that described for hairy skin D-hair receptors. Glabrous D-hair receptors do not occur in all rodents, but are present in North American and African rodent species that diverged more than 65 million years ago. The function of these specialized hairs is unknown, but they are nevertheless evolutionarily very ancient. Our study reveals novel physiological specializations of mechanoreceptors in the glabrous skin that likely evolved to facilitate tactile exploration.

Comparison of Concurrent and Retrospective Pain Ratings during Rehabilitation Following Anterior Cruciate Ligament Reconstruction

2004 ◽  
Vol 26 (4) ◽  
pp. 610-615 ◽  
Author(s):  
Britton W. Brewer ◽  
Allen E. Cornelius ◽  
Judy Van Raalte ◽  
John C. Brickner ◽  
Howard Tennen ◽  
...  
Keyword(s):  
Anterior Cruciate Ligament ◽  
Anterior Cruciate Ligament Reconstruction ◽  
Pain Intensity ◽  
Ligament Reconstruction ◽  
Cruciate Ligament ◽  
Cruciate Ligament Reconstruction ◽  
Average Pain Intensity ◽  
Pain Ratings ◽  
Average Pain ◽  
Anterior Cruciate

The accuracy of retrospective ratings of pain intensity was examined in a sample of 72 men and 36 women undergoing rehabilitation following anterior cruciate ligament (ACL) reconstructive surgery. Participants completed daily ratings of current, worst, and average pain intensity for the first 42 days of rehabilitation. Participants provided retrospective ratings of worst and average pain intensity twice for a 7-day period (on Days 7 and 21) and once for a 30-day period (on Day 30). Correlations between concurrent and retrospective pain ranged from .74 to .88. Retrospective pain ratings consistently overestimated concurrent pain ratings, but were generally not biased by current pain. The results suggest that retrospective pain ratings can substitute for concurrent pain ratings if the tendency toward overestimation is taken into account.

Time-intensity profiles of cutaneous pain in normal and hyperalgesic skin: a comparison with C-fiber nociceptor activities in monkey and human

1984 ◽  
Vol 51 (6) ◽  
pp. 1434-1450 ◽  
Author(s):  
R. H. LaMotte ◽  
H. E. Torebjork ◽  
C. J. Robinson ◽  
J. G. Thalhammer
Keyword(s):  
Normal Skin ◽  
Similar Response ◽  
Response Latencies ◽  
Median Response ◽  
Hairy Skin ◽  
Afferent Fibers ◽  
C Fiber ◽  
Before And After ◽  
Pain Ratings ◽  
Temporal Profiles

Contributions of evoked discharge in nociceptors with C-fibers to the temporal profiles of magnitude judgments of pain by humans were determined for heat stimulations of the skin before and after the development of hyperalgesia (increased sensitivity to pain) produced by a mild heat injury. Human subjects continuously rated the magnitude of pain evoked by short-duration heat stimuli of 39-51 degrees C delivered to the hairy skin of the arm or leg (calf or foot) before and after the development of hyperalgesia produced by a conditioning stimulus (CS) of either 50 degrees C for 100 s or 48 degrees C for 360 s. During heat stimulations of the leg in humans, magnitude judgments of pain were obtained simultaneously with recordings of evoked discharges in single C-fiber mechanoheat (CMH) nociceptive afferent fibers. Seven fibers were studied before and after the CS. In other experiments, magnitude ratings of pain evoked by heat stimulations of the arm were compared with heat-evoked discharges in 21 CMH nociceptive afferent fibers innervating the hairy skin of the wrist or hand in anesthetized monkeys. From CMH responses obtained in each species, median response latencies were calculated as well as poststimulus time (PST) histograms--the latter plotting mean frequency of discharge versus time during each stimulus. In these analyses, the times of action potentials in CMHs were calculated as they would occur at entry to the lumbar or cervical spinal cord in humans, taking into account the temporal dispersion that should occur because of differing conduction velocities. These results were then compared with response latencies for pain and the temporal profiles of pain ratings made by individual subjects. Comparisons were made for data obtained before the CS (normal skin) and those obtained 10 min after the CS in heat-sensitized (hyperalgesic) skin. For normal skin, PST histograms of mean frequencies of discharge were similar for CMHs with similar heat thresholds (41-43 degrees) in the anesthetized monkey and the awake human. Despite minor discrepancies, there were similarities in the changes in these histograms for monkey and human CMHs following heat sensitization after the CS. It was concluded that CMHs in monkeys and humans have similar response magnitudes and temporal profiles of response to heat. The major differences in the temporal profiles of CMH responses and human pain ratings were the latencies at which CMH responses and pain ratings began, reached maximum, and ended.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Evidence for sparse C-tactile afferent innervation of glabrous human hand skin

2020 ◽  
Author(s):  
Roger H Watkins ◽  
Mariama Dione ◽  
Rochelle Ackerley ◽  
Helena Backlund Wasling ◽  
Johan Wessberg ◽  
...  
Keyword(s):  
Firing Frequency ◽  
Glabrous Skin ◽  
Whole Body ◽  
Human Hand ◽  
Hairy Skin ◽  
Ct Afferents ◽  
Touch Perception ◽  
The Face ◽  
Nerve Recordings ◽  
Future Work

C-tactile (CT) afferents were long-believed to be lacking in humans, but were subsequently shown to densely innervate the face and arm skin, and to a lesser extent the leg. Their firing frequency to stroking touch at different velocities has been correlated with ratings of tactile pleasantness. CT afferents were thought to be absent in human glabrous skin; however, tactile pleasantness can be perceived across the whole body, including glabrous hand skin. We used microneurography to investigate mechanoreceptive afferents in the glabrous skin of the human hand, during median and radial nerve recordings. We describe CTs found in the glabrous skin, with comparable characteristics to those in hairy arm skin, and detail recordings from three such afferents. CTs were infrequently encountered in the glabrous skin and we estimate that the ratio of recorded CTs relative to myelinated mechanoreceptors (1:80) corresponds to an absolute innervation density of around 7 times lower than in hairy skin. This sparse innervation sheds light on discrepancies between psychophysical findings of touch perception on glabrous skin and hairy skin, although the role of these CT afferents in the glabrous skin remains subject to future work.

scholarly journals XXII. On the thermal resistance of liquids

1869 ◽  
Vol 159 ◽  
pp. 637-660 ◽  
Keyword(s):  
Thermal Resistance ◽  
Royal Society ◽  
Radiant Heat ◽  
Experimental Results ◽  
Contact Heat ◽  
The Subject

§ 1. The passage of heat through matter has been mainly examined in reference to the diathermancy of solids, liquids, and gases to radiant heat, and to the conduction of contact-heat through solids and gases. The conduction of contact-heat through liquids forms a chapter in heat transference which has not hitherto received as much attention from experimental physicists as it merits. § 2. In the following pages I have the honor of submitting to the Royal Society certain experimental results and considerations to which I have been led during an investigation of this subject. These results are necessarily incomplete. The inquiry is fraught with very numerous and considerable experimental difficulties; but I venture to hope that such as the results are, they may be found useful to those who shall hereafter pursue the subject with greater skill and more perfect appliances.

Microscopic Modeling of the Effects of Autonomous Vehicles on Motorway Performance

2020 ◽  
Vol 2674 (11) ◽  
pp. 697-707
Author(s):  
George Mesionis ◽  
Mark Brackstone ◽  
Natalie Gravett
Keyword(s):  
Automotive Industry ◽  
Autonomous Vehicles ◽  
Behavioral Model ◽  
Cruise Control ◽  
Lane Changing ◽  
Positive Effects ◽  
Traffic Conditions ◽  
High Penetration ◽  
The Subject ◽  
Microscopic Modeling

Autonomous vehicles (AVs) have been the subject of extensive research in recent years and are expected to completely transform the operation of transport networks and revolutionize the automotive industry in the coming decades. Modeling detailed interactions among vehicles with varying levels of penetration rates is essential for evaluating the potential effects. One such investigation is being performed within the ‘HumanDrive’ Project in the U.K. This work has required the development of a behavioral model that incorporates microscopic level interactions and has been based on a pre-existing adaptive cruise control and lane-changing model that has been adapted to better replicate the limitations of AVs and allow the investigation of differing levels of intelligence or assertiveness. The model has been implemented on the M1 Motorway near Sheffield in the U.K. This has allowed the investigation of the effects of AVs on the operation of a real network under various traffic conditions where the overall effects may be revealed, both as advantages to AV drivers, and potentially disadvantages to non-AV traffic. Additionally, it has been possible to examine how these affect junction operations and net emissions. Preliminary results have allowed us to quantify the positive effects of AVs which increase with the penetration. However, it is clear that there are points of inflection where benefits start to slow. It is at these (high) penetration rates that initial operational assumptions may become increasingly stretched and additional infrastructure and cooperative systems are likely to have to become prevalent.

The effect of nerve compression and capsaicin on contact heat evoked potentials (CHEPs) related to Aδ and C fibers

2012 ◽  
Vol 3 (3) ◽  
pp. 187-187
Author(s):  
C.S. Madsen ◽  
B. Johnsen ◽  
A. Fuglsang-Frederiksen ◽  
T.S. Jensen ◽  
N.B. Finnerup
Keyword(s):  
Evoked Potentials ◽  
Pain Intensity ◽  
Radial Nerve ◽  
Nerve Compression ◽  
Contact Heat ◽  
Noxious Heat ◽  
Superficial Radial Nerve ◽  
C Fibers ◽  
Contact Heat Evoked Potentials ◽  
C Fiber

Abstract Background/aims Brief noxious heat stimuli activate Aδ and C fibers, and contact heat evoked potentials (CHEPs) can be recorded from the scalp. Under standard conditions, late responses related to AS fibers can be recorded. This study examines C-fiber responses to contact heat stimuli. Methods A preferential A-fiber blockade by compression to the superficial radial nerve was applied in 22 healthy subjects. Quality and intensity of heat evoked pain (NRS, 0–10), and CHEPs were examined at baseline, during nerve compression, and during further nerve compression with topical capsaicin (5%). Results During the A-fiber blockade, 3 subjects had CHEPs with latencies below 400 ms, 8 subjects within 400–800 ms and 6 subjects later than 800 ms. Pain intensity to contact heat stimuli was reduced and fewer subjects reported the heat stimuli as stinging. Following acute capsaicin application, ultralate CHEPs with latencies >800 ms could be recorded in 13 subjects, pain intensity to the contact heat stimuli was increased (p <0.01) and more subjects reported the heat stimuli as being more warm/hot-burning. Conclusion The results indicate that following a compression to the superficial radial nerve, CHEPs compatible within complete A fibers or C fibers were recorded. Following sensitization with capsaicin, C-fiber responses were recorded in 62% of subjects.

scholarly journals Stress-Induced Mast Cell Activation in Glabrous and Hairy Skin

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Constantin Căruntu ◽  
Daniel Boda ◽  
Sorin Musat ◽  
Ana Căruntu ◽  
Eugen Mandache
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Activation ◽  
Prolonged Exposure ◽  
Mast Cell Degranulation ◽  
Mast Cell Activation ◽  
Glabrous Skin ◽  
Stress Exposure ◽  
Hairy Skin ◽  
The Impact

Mast cells play a key role in modulation of stress-induced cutaneous inflammation. In this study we investigate the impact of repeated exposure to stress on mast cell degranulation, in both hairy and glabrous skin. Adult male Wistar rats were randomly divided into four groups: Stress 1 day(n=8), Stress 10 days(n=7), Stress 21 days(n=6), and Control(n=8). Rats in the stress groups were subjected to 2 h/day restraint stress. Subsequently, glabrous and hairy skin samples from animals of all groups were collected to assess mast cell degranulation by histochemistry and transmission electron microscopy. The impact of stress on mast cell degranulation was different depending on the type of skin and duration of stress exposure. Short-term stress exposure induced an amplification of mast cell degranulation in hairy skin that was maintained after prolonged exposure to stress. In glabrous skin, even though acute stress exposure had a profound stimulating effect on mast cell degranulation, it diminished progressively with long-term exposure to stress. The results of our study reinforce the view that mast cells are active players in modulating skin responses to stress and contribute to further understanding of pathophysiological mechanisms involved in stress-induced initiation or exacerbation of cutaneous inflammatory processes.

Vibrotactile Frequency Discrimination in Human Hairy Skin

2006 ◽  
Vol 95 (3) ◽  
pp. 1442-1450 ◽  
Author(s):  
D. A. Mahns ◽  
N. M. Perkins ◽  
V. Sahai ◽  
L. Robinson ◽  
M. J. Rowe
Keyword(s):  
Detection Threshold ◽  
Weber Fraction ◽  
Frequency Discrimination ◽  
Glabrous Skin ◽  
Striking Similarity ◽  
Discriminative Performance ◽  
Detection Thresholds ◽  
Low Frequencies ◽  
Hairy Skin ◽  
Finger Tip

The human capacity for vibrotactile frequency discrimination has been compared directly for glabrous and hairy skin regions by means of a two-alternative, forced-choice psychophysical procedure in five subjects. Sinusoidal vibratory stimuli, delivered by means of a 4-mm-diam probe, were first used to obtain detection threshold values for the two skin sites, the finger tip and the dorsal forearm, at four standard frequencies, 20, 50, 100, and 200 Hz. Values confirmed previous results showing detection thresholds were markedly higher on hairy skin than on glabrous skin. For the discrimination task, each standard frequency, at an amplitude four times detection threshold, was paired with a series of comparison frequencies, and discrimination capacity then was quantified by deriving from psychometric function curves, measures of the discriminable frequency increment (Δƒ) and the Weber Fraction (Δƒ/ƒ), which, when plotted as a function of the four standard frequencies, revealed similar capacities for frequency discrimination at the two skin sites at the standard frequencies of 20, 100, and 200 Hz but an equivocal difference at 50 Hz. Cutaneous local anesthesia produced a marked impairment in vibrotactile detection and discrimination at the low standard frequencies of 20 and 50 Hz but little effect at higher frequencies. In summary, the results reveal, first, a striking similarity in vibrotactile discriminative performance in hairy and glabrous skin despite marked differences in detection thresholds for the two sites, and, second, the results confirm that vibrotactile detection and discrimination in hairy skin depend on superficial receptors at low frequencies but depend on deep, probably Pacinian corpuscle, receptors for high frequencies.

Transient Analgesia Evoked by Noxious Stimulus Offset

2002 ◽  
Vol 87 (4) ◽  
pp. 2205-2208 ◽  
Author(s):  
Joshua D. Grill ◽  
Robert C. Coghill
Keyword(s):  
Chronic Pain ◽  
Pain Intensity ◽  
Relative Proportion ◽  
Noxious Stimulus ◽  
Temporal Contrast ◽  
Nociceptive Processing ◽  
Perceived Pain ◽  
Pain Ratings ◽  
Stimulus Offset ◽  
Escape Behaviors

Pain has long been thought to wax and wane in relative proportion to fluctuations in the intensity of noxious stimuli. Dynamic aspects of nociceptive processing, however, remain poorly characterized. Here we show that small decreases (±1–3°C) in noxious stimulus temperatures (47–50°C) evoked changes in perceived pain intensity that were as much as 271% greater than those of equal magnitude increases. These decreases in perceived pain intensity were sufficiently large to be indistinguishable from those evoked by 15°C decreases to clearly innocuous levels. Furthermore, decreases in pain ratings following noxious stimulus offset were significantly greater than those occurring during adaptation to constant temperature stimuli. Together, these findings indicate that an analgesic mechanism is activated during noxious stimulus offset. This analgesic phenomenon may serve as a temporal contrast enhancement mechanism to amplify awareness of stimulus offset and to reinforce escape behaviors. Disruption of this mechanism may contribute importantly to chronic pain.

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