Comparison of responses of warm and nociceptive C-fiber afferents in monkey with human judgments of thermal pain

1978 ◽  
Vol 41 (2) ◽  
pp. 509-528 ◽  
Author(s):  
R. H. LaMotte ◽  
J. N. Campbell
Keyword(s):  
Skin Temperature ◽  
Conduction Velocity ◽  
Mechanical Stimulation ◽  
Human Subjects ◽  
Radiant Heat ◽  
Cumulative Number ◽  
Painful Stimulation ◽  
C Fibers ◽  
Nociceptive Afferents ◽  
Stimulus Temperature

1. Radiant-heat stimuli of different intensities were delivered every 28 s to the thenar eminence of the hand of human subjects and to the receptive fields (RFs) of 58 "mechanothermal nociceptive" and 16 "warm" C-fibers, most of which innervated the glabrous skin of the monkey hand. A CO2 infrared laser under control via a radiometer provided a step increase in skin temperature to a level maintained within +/- 0.1 degrees C over a 7.5-mm-diameter spot. 2. Human subjects categorized the magnitude of warmth and pain sensations evoked by stimuli that ranged in temperature from 40 to 50 degrees C. The scale of subjective thermal intensity constructed from these category estimates showed a monotonically increasing relation between stimulus temperature and the magnitude of warmth and pain sensations. 3. The mechanothermal fibers had a mean RF size of 18.9 +/- 3.2 mm2 (SE), a mean conduction velocity of 0.8 +/- 0.1 m/s, mean thresholds of 43.6 +/- 0.6 degrees C for radiant heat and 5.95 +/- 0.59 bars for mechanical stimulation, and no spontaneous activity. In contrast, warm fibers had punctate RFs, a mean conduction velocity of 1.1 +/- 0.1 m/s, heat thresholds of less than 1 degrees C above skin temperature, no response to mechanical stimulation, and a resting level of activity in warm skin that was suppressed by cooling. 4. The cumulative number of impulses evoked during each stimulation in the nociceptive afferents increased monotonically as a function of stimulus temperature over the range described by humans as increasingly painful (45-50 degrees C). Nociceptive fibers showed little or no response to stimulus temperatures less than 45 degrees C that elicited in humans sensations primarily of warmth but not pain. In contrast, the cumulative impulse count during stimulation of each warm fiber increased monotonically with stimulus temperature over the range of 39-43 degrees C. However, for stimuli of 41-49 degrees C the cumulative impulse count in warm fibers was nonmonotonic with stimulus temperature. Warm-fiber response to stimuli of 45 degrees C or greater usually consisted of a short burst of impulses followed by cessation of activity. 5. The subjective magnitude of warmth and pain sensations in humans and the cumulative impulse count evoked by each stimulus in warm and nociceptive afferents varied inversely with the number, delivery rate, and intensity of preceding stimulations. 6. The results of these experiments suggest the following: a) that activity in the mechanothermal nociceptive C-fibers signals the occurrence of pain evoked by radiant heat, and that the frequency of discharge in these fibers may encode the intensity of painful stimulation; b) that activity in warm fibers may encode the intensity of warmth at lower stimulus temperatures, but is unlikely to provide a peripheral mechanism for encoding the intensity of painful stimulation at higher stimulus temperatures.

Activity-dependent variations in conduction velocity of C fibers of rat sciatic nerve

1994 ◽  
Vol 19 (4) ◽  
pp. 427-431 ◽  
Author(s):  
Hyung-Cheul Shin ◽  
Yun-Lyul Lee ◽  
Hyeok-Yil Kwon ◽  
Hyoung Jin Park ◽  
Stephen A. Raymond
Keyword(s):  
Sciatic Nerve ◽  
Conduction Velocity ◽  
Rat Sciatic Nerve ◽  
C Fibers ◽  
Activity Dependent

An Examination by Forearm EMG on Pain Reaction Time to Radiant Heat

1993 ◽  
Vol 76 (3_suppl) ◽  
pp. 1139-1146 ◽  
Author(s):  
Toshiteru Hatayama ◽  
Kayoko Shimizu
Keyword(s):  
Reaction Time ◽  
Time Delay ◽  
Skin Temperature ◽  
Motor Response ◽  
Pain Threshold ◽  
Radiant Heat ◽  
Repeated Measurements ◽  
Pain Sensation ◽  
Pain Thresholds ◽  
Pain Reaction

The present study was done to estimate rise in skin temperature during a pain reaction time (pain RT) as a means of investigating why a pricking pain threshold, produced by thermal stimulation using time method, often increases during repeated measurements. The pain RT, or the time-delay between occurrence of pain sensation and a subsequent motor response, was measured by making EMG recording on a forearm. The radiant heat stimuli were three, 200, 300, and 350 mcal/sec./cm2, each of which was given through a round radiation window of an algesiometer head. Analysis showed that the pain RTs would be too short to explain higher pain thresholds often found using the time method.

Mechanical sensitivity of group III and IV afferents from posterior articular nerve in normal and inflamed cat knee

1986 ◽  
Vol 55 (4) ◽  
pp. 635-643 ◽  
Author(s):  
P. Grigg ◽  
H. G. Schaible ◽  
R. F. Schmidt
Keyword(s):  
Sciatic Nerve ◽  
Knee Joint ◽  
Conduction Velocity ◽  
Mechanical Stimulation ◽  
Dorsal Root ◽  
Receptive Fields ◽  
Group Iv ◽  
Mechanical Sensitivity ◽  
Group Iii ◽  
Stimulation Of

Recordings were performed from sciatic nerve or dorsal root filaments in 28 cats to study single group III (conduction velocity 2.5-20 m/s) and group IV (conduction velocity less than 2.5 m/s) units supplying the knee joint via the posterior articular nerve (PAN). In seven of these cats the knee joint had been inflamed artificially. Recordings from sciatic nerve filaments revealed responses to local mechanical stimulation of the joint in only 3 of 41 group IV units and in 12 of 18 group III units from the normal joint. In the inflamed joint 14 of 36 group IV units and 24 of 36 group III units were excited with local mechanical stimulation. In recordings from dorsal root filaments (normal joint) 4 of 11 group IV units and 7 of 13 group III units were activated by stimulating the joint locally. In the normal joint four group IV units (recorded from dorsal root filaments) responded only to rotations against the resistance of the tissue, whereas the majority of the fibers did not respond even to forceful movements. Group III units with local mechanosensitivity in the normal joint reacted strongly or weakly to movements in the working range of the joint or only to movements against resistance of the tissue. In the inflamed joint, group IV fibers (recorded in sciatic nerve filaments) with detectable receptive fields responded strongly to gentle movements or only to movements against resistance of tissue. Some did not react to movements. Group III units reacted strongly or weakly to gentle movements or only to movements against resistance of the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Sweating and body temperatures following abrupt changes in environmental temperature

1962 ◽  
Vol 17 (1) ◽  
pp. 103-106 ◽  
Author(s):  
H. S. Belding ◽  
B. A. Hertig
Keyword(s):  
Skin Temperature ◽  
Environmental Temperature ◽  
Sweat Rate ◽  
Human Subjects ◽  
Body Temperatures ◽  
Hypothalamic Temperature ◽  
Abrupt Changes ◽  
Consistent Change ◽  
Different Levels ◽  
Skin Receptors

Human subjects were transferred between environments imposing different levels of heat stress. Analyses of measurements obtained after a reasonably steady state had been achieved in each of several environments revealed equally good correlation between a) sweat rate and ear temperature (tympanic membrane), and b) sweat rate and calculated deep skin temperature (hypothetical). The correlations are consistent with adjustment of sweating in response to either hypothalamic temperature or temperature of skin receptors or some combination of the two. However, during the first 20 min after transfer, changes in sweat rate and skin temperature occurred together and in the same direction, but were not accompanied by any consistent change in ear temperature. Thus, to the extent that ear temperature represents hypothalamic temperature, an hypothesis of control of sweating based on hypothalamic temperature alone is not tenable. Alternative physiological explanations are given for data developed elsewhere and used in support of an hypothesis of sweat control solely from the hypothalamus. Submitted on August 14, 1961

Spontaneous skin temperature oscillations in normal human subjects

1997 ◽  
Vol 273 (3) ◽  
pp. R1173-R1181 ◽  
Author(s):  
V. Shusterman ◽  
K. P. Anderson ◽  
O. Barnea
Keyword(s):  
Skin Temperature ◽  
Muscle Tone ◽  
Human Subjects ◽  
Spectral Characteristics ◽  
Peak Frequency ◽  
Temperature Variability ◽  
Spectral Energy ◽  
Temperature Oscillations ◽  
Normal Human ◽  
Vasomotor Activity

A noninvasive method based on high-resolution measurements and bandpass filtering of spontaneous skin temperature oscillations (approximately 4.0 x 10(-2) degrees C) in the low-frequency range (0.01-0.04 Hz) was investigated in normal human subjects. We hypothesized that the oscillations (temperature variability) originate from vasomotor activity of small arteries and arterioles in subcutaneous tissues. To test this hypothesis, continuous blood pressure waveforms were obtained with the use of an external piezoelectric sensor. The peak-to-peak envelope of the pressure signal (pressure variability) was used as an indicator of vasomotor activity. The variabilities of temperature and pressure were compared using cross-spectral and coherence analysis. The correlation between the peak frequency of the signals was 0.92, and the coherence was greater than 0.9. The signals demonstrated similar changes in spectral energy and peak frequency in response to mental stress. Reproducibility of the temperature variability in individual subjects was verified by repeating measurements 1-12 wk later. The differences in peak frequency were small (0.0155 +/- 0.001 Hz), and in each subject the signals exhibited similar patterns in response to stress. Correlation between spectral characteristics of the signals suggests that temperature variability can be attributed to changes in blood flow resulting from oscillations in vasomotor smooth muscle tone.

Protection of Sensory Function and Antihyperalgesic Properties of a Prosaposin-derived Peptide in Diabetic Rats

2000 ◽  
Vol 93 (5) ◽  
pp. 1271-1278 ◽  
Author(s):  
Nigel A. Calcutt ◽  
Jason D. Freshwater ◽  
John S. O’Brien
Keyword(s):  
Conduction Velocity ◽  
Single Injection ◽  
Intrathecal Injection ◽  
Sensory Nerve ◽  
Radiant Heat ◽  
Diabetic Rats ◽  
Sensory Function ◽  
Formalin Injection ◽  
Weekly Dose ◽  
Sensory Stimuli

Background Short-term diabetes causes sensory disorders in rats ranging from thermal hypoalgesia to exaggerated behavioral responses to other sensory stimuli. As impaired neurotrophic support may promote sensory nerve disorders during diabetes, the authors investigated whether TX14(A), a neurotrophic peptide derived from prosaposin, was able to ameliorate nerve disorders in diabetic rats. Methods TX14(A) was delivered by intraperitoneal or intrathecal injection to control or streptozotocin-diabetic rats in either single or multiple (three times weekly) dose regimens. Efficacy was measured against diabetes-induced disorders of sensory nerve conduction velocity, paw withdrawal latency to radiant heat, tactile response thresholds to von Frey filaments, and flinching after paw formalin injection. Results Prolonged TX14(A) treatment of diabetic rats prevented the progressive decline in large sensory fiber conduction velocity in the sciatic nerve, development of paw thermal hypoalgesia, and increased flinching after paw formalin injection. The effect on formalin hyperalgesia persisted for 48 h but not 72 h after injection. No effects were noted in control rats. A single injection of TX14(A) 30 min before testing did not alter thermal response latencies in control or diabetic rats but prevented formalin hyperalgesia in diabetic rats. Tactile allodynia and the prolonged paw thermal hyperalgesia to radiant heat after intrathecal delivery of substance P were also dose-dependently ameliorated in diabetic rats by a single injection of TX14(A), whereas no effects were observed on the responses to these tests in control rats. Conclusions TX14(A) exhibits both neuroprotective and acute antihyperalgesic properties in diabetic rats without altering normal nociceptive function.

The Effect of Pressure on Skin Temperature Measurements for a Disk Sensor

1979 ◽  
Vol 101 (4) ◽  
pp. 261-266 ◽  
Author(s):  
S. D. Mahanty ◽  
R. B. Roemer
Keyword(s):  
Skin Temperature ◽  
Human Subjects ◽  
Reactive Hyperemia ◽  
Circular Disk ◽  
Temperature Measurements ◽  
Whole Body ◽  
Local Pressure ◽  
Local Skin ◽  
Local Skin Temperature ◽  
Skin Temperatures

In order to determine the effect of application pressure on the accuracy of skin temperature measurements for area contact sensors, low values of pressure (2-20 mm Hg) were applied to the mid-thigh and to the lateral aspect of the trochanter of human subjects using a thin, circular disk with a thermistor mounted in the base. From measurements of the local skin temperatures, it was determined that a pressure of 2 mm Hg is adequate to measure the skin temperature accurately. Applying larger pressure results in higher local skin temperatures with the thighs showing larger temperature increases than the trochanters. The results of a finite difference analysis indicate that the increases in skin temperature at higher pressures can be accounted for by the physical phenomena associated with the penetration of the sensor into the tissue. After the release of pressure, the local skin temperature immediately decreased for all subjects indicating little or no reactive hyperemia was occurring. A method of compensating for the changes in local skin temperature which are due to whole body transient thermal effects was also developed. Use of this method allows the effects of the local pressure application to be separated from the transient environmental effects.

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