Spatial summation of heat-induced pain: influence of stimulus area and spatial separation of stimuli on perceived pain sensation intensity and unpleasantness

1989 ◽  
Vol 62 (6) ◽  
pp. 1270-1279 ◽  
Author(s):  
D. D. Price ◽  
J. G. McHaffie ◽  
M. A. Larson
Keyword(s):  
Spatial Summation ◽  
Stimulus Size ◽  
Experimental Series ◽  
Pain Sensation ◽  
Thermal Probe ◽  
Spinothalamic Tract ◽  
Nociceptive Neurons ◽  
Thermal Probes ◽  
Perceived Pain ◽  
Thermal Stimuli

1. Psychophysical experiments were initiated to determine the possible influence of increasing stimulus size on perceived pain intensity. Six trained human subjects (5 male, 1 female) made visual analogue scale (VAS) ratings for pain-sensation intensity and unpleasantness in response to nociceptive thermal stimuli. Test stimuli consisted of 5-s duration heat pulses (45-50 degrees C in 1 degrees increments) delivered by one, two, or three contact thermal probes (1 cm2 each) applied to the medial aspect of the anterior forearm. 2. The area of skin receiving noxious thermal stimuli was changed by randomly varying the number of thermodes activated. The effects of varying the distance between the thermal probes also were evaluated. In the first series of experiments, thermal-probe separation was kept close to 0; in subsequent experimental series, the thermodes were separated by either 5 or 10 cm. 3. In each experimental series, considerable spatial summation occurred in both pain-sensation intensity and unpleasantness dimensions of pain. This summation occurred throughout the nociceptive thermal range of 45-50 degrees C and was larger at suprathreshold temperatures (greater than or equal to 47 degrees C) than those near threshold (less than or equal to 46 degrees C). Unlike spatial summation of perceived warmth, that of pain was not characterized by systematic changes in power-function exponents but as approximately upward parallel displacements in double-logarithmic coordinates. 4. Thermal-probe separation over a range of 0-10 cm had no effects on spatial summation of pain-sensation intensity or pain unpleasantness. In contrast, increasing thermal-probe separation increased the subjects' ability to discriminate differences in stimulus size and their ability to detect correctly the number of thermal probes activated. 5. Because affective VAS ratings of unpleasantness were linearly related to, but distinctly and systematically less than, VAS ratings of pain-sensation intensity, it was clear that subjects responded quite differently to these two pain dimensions. Affective judgements were not additionally influenced by thermal probe separation and hence by the ability to perceive stimulus size or number of thermal probes activated. 6. The results indicate that powerful spatial-summation mechanisms exist for heat-induced pain. Spatial summation of pain is likely to be subserved both by local integration mechanisms at the level of single spinothalamic-tract neurons and by recruitment of central nociceptive neurons, because spatial summation of pain occurred to approximately equal extents under conditions of thermode separations over a distance of at least 20 cm.

Responses of nociceptive SI neurons in monkeys and pain sensation in humans elicited by noxious thermal stimulation: effect of interstimulus interval

1990 ◽  
Vol 63 (3) ◽  
pp. 559-569 ◽  
Author(s):  
E. H. Chudler ◽  
F. Anton ◽  
R. Dubner ◽  
D. R. Kenshalo
Keyword(s):  
Linear Regression ◽  
Interstimulus Interval ◽  
Thermal Stimulation ◽  
Regression Coefficients ◽  
Response Functions ◽  
Neuronal Responses ◽  
Pain Sensation ◽  
Nociceptive Neurons ◽  
Stimulus Response ◽  
Thermal Stimuli

1. Twenty-six nociceptive neurons in the primary somatosensory cortex (SI) of anesthetized monkeys were responsive to noxious thermal stimulation applied to the face. Thermode temperature increased from a base line of 38 degrees C to temperatures ranging from 44 to 49 degrees C (T1). After a period of 5 s, the temperature increased an additional 1 degree C (T2). The neuronal responses to noxious thermal stimuli were compared when the interstimulus interval (ISI) was 30 or 180 s. 2. A linear regression analysis was applied to the stimulus-response functions of neuronal responses to T1 stimuli obtained at ISIs of 180 s. Based on the slopes and linear regression coefficients of these stimulus-response functions, two populations of nociceptive neurons were identified. The neuronal responses of one population of nociceptive SI neurons (WDR1) to T1 stimuli were characterized by steep slopes and high regression coefficients, whereas the other population (WDR2) had flatter slopes and lower regression coefficients. WDR1 neurons responded with monotonic increases in neuronal activity as the stimulus intensity increased. However, the peak frequency of WDR2 neurons often reached a plateau below 47 degrees C. Both WDR1 and WDR2 neurons had receptive fields that encompassed one or two divisions of the trigeminal nerve. 3. The T1 neuronal responses of WDR1 neurons were significantly suppressed when thermal stimuli were delivered with ISIs of 30 s. The T1 neuronal responses of WDR2 and the T2 responses of both WDR1 and WDR2 neurons were not significantly different when ISIs of 30 and 180 s were used. The T1 thresholds of WDR1 and WDR2 neurons were significantly higher when stimuli were delivered with ISIs of 30 s compared with ISIs of 180 s. 4. Most nociceptive SI neurons were located in layers III and IV of area 1-2. In a number of instances, multiple nociceptive neurons were found in the same microelectrode penetration. 5. The humans' intensity of pain sensation paralleled the neuronal responses of nociceptive SI neurons. With the use of a similar paradigm as in the monkey experiments, increases in T1 and T2 temperatures resulted in monotonic increases in pain ratings and change in pain sensation, respectively. However, the intensity of pain sensation to T1 temperatures was suppressed by ISIs of 30 s. Neither ISI produced statistically significant changes in the intensity of pain sensation to T2 stimuli. 6. These data demonstrate that manipulations that alter the intensity of pain sensation also produce concomitant changes in the responsiveness of nociceptive SI neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals The input-output relation of primary nociceptive neurons is determined by the morphology of the peripheral nociceptive terminals

2020 ◽  
Author(s):  
Omer Barkai ◽  
Rachely Butterman ◽  
Ben Katz ◽  
Shaya Lev ◽  
Alexander M. Binshtok
Keyword(s):  
Action Potential ◽  
Input Output ◽  
Pain Sensation ◽  
Action Potential Firing ◽  
Nociceptive Neurons ◽  
Pathological Conditions ◽  
Potential Firing ◽  
Noxious Stimuli ◽  
The Individual ◽  
Neuronal Output

AbstractThe output from the peripheral terminals of primary nociceptive neurons, which detect and encode the information regarding noxious stimuli, is crucial in determining pain sensation. The nociceptive terminal endings are morphologically complex structures assembled from multiple branches of different geometry, which converge in a variety of forms to create the terminal tree. The output of a single terminal is defined by the properties of the transducer channels producing the generation potentials and voltage-gated channels, translating the generation potentials into action potential firing. However, in the majority of cases, noxious stimuli activate multiple terminals; thus, the output of the nociceptive neuron is defined by the integration and computation of the inputs of the individual terminals. Here we used a computational model of nociceptive terminal tree to study how the architecture of the terminal tree affects input-output relation of the primary nociceptive neurons. We show that the input-output properties of the nociceptive neurons depend on the length, the axial resistance, and location of individual terminals. Moreover, we show that activation of multiple terminals by capsaicin-like current allows summation of the responses from individual terminals, thus leading to increased nociceptive output. Stimulation of terminals in simulated models of inflammatory or nociceptive hyperexcitability led to a change in the temporal pattern of action potential firing, emphasizing the role of temporal code in conveying key information about changes in nociceptive output in pathological conditions, leading to pain hypersensitivity.Significance statementNoxious stimuli are detected by terminal endings of the primary nociceptive neurons, which are organized into morphologically complex terminal trees. The information from multiple terminals is integrated along the terminal tree, computing the neuronal output, which propagates towards the CNS, thus shaping the pain sensation. Here we revealed that the structure of the nociceptive terminal tree determines the output of the nociceptive neurons. We show that the integration of noxious information depends on the morphology of the terminal trees and how this integration and, consequently, the neuronal output change under pathological conditions. Our findings help to predict how nociceptive neurons encode noxious stimuli and how this encoding changes in pathological conditions, leading to pain.

Responses of spinothalamic tract cells to mechanical and thermal stimulation of skin in rats with experimental peripheral neuropathy

1992 ◽  
Vol 67 (6) ◽  
pp. 1562-1573 ◽  
Author(s):  
J. Palecek ◽  
V. Paleckova ◽  
P. M. Dougherty ◽  
S. M. Carlton ◽  
W. D. Willis
Keyword(s):  
Dynamic Range ◽  
Background Activity ◽  
Thermal Stimulation ◽  
Spontaneous Pain ◽  
Mechanical Stimuli ◽  
Spinothalamic Tract ◽  
High Background ◽  
Threshold Temperatures ◽  
Thermal Stimuli ◽  
Stimulation Of

1. Responses of spinothalamic tract (STT) neurons to mechanical and thermal stimulation of skin were recorded under urethane and pentobarbital anesthesia in 12 control rats and in 20 rats with experimental neuropathy. Activity of the STT cells in neuropathic rats was recorded 7, 14, and 28 days after inducing the neuropathy by placing four loose ligatures on the sciatic nerve. 2. All neuropathic animals showed guarding of the injured hindpaw and a shorter withdrawal latency from a radiant heat source of the neuropathic hindpaw than that of the sham-operated paw. 3. STT neurons in neuropathic animals showed the most profound changes 7 and 14 days after the nerve ligation. When compared with STT cells in unoperated animals, approximately half of the neurons had high background activity, responses to innocuous stimuli represented a larger percentage of the total evoked activity in wide dynamic range neurons, and the occurrence and magnitude of afterdischarges to mechanical and thermal stimuli were increased. 4. The mean threshold temperatures of heat-evoked responses of the STT cells in neuropathic animals were not different than those of cells from control animals. However, in neuropathic rats, cells reacting to small heat stimuli usually already had afterdischarges. 5. The increase in the background activity of STT cells is consistent with behavioral observations of spontaneous pain in this model of experimental neuropathy. Furthermore, the afterdischarges of STT cells may parallel the prolonged paw withdrawal in response to noxious stimuli that is seen in these animals and that is evidence for hyperalgesia. However, there was no indication of a lowered threshold for thermal stimuli as might be expected if the animals have thermal allodynia. Mechanical allodynia may have resulted from a relative increase in responsiveness to innocuous mechanical stimuli. However, responses to noxious mechanical stimuli were reduced compared with control, at least at 28 days after the ligation. Peripheral and central mechanisms responsible for the changes in responses of STT cells in neuropathic animals are suggested.

Placing pain on the sensory map: Classic papers by Ed Perl and colleagues

2007 ◽  
Vol 97 (3) ◽  
pp. 1871-1873 ◽  
Author(s):  
Peggy Mason
Keyword(s):  
Dorsal Horn ◽  
Marginal Zone ◽  
Superficial Dorsal Horn ◽  
Spinal Neurons ◽  
Nociceptive Neurons ◽  
Unmyelinated Fibers ◽  
Noxious Stimuli ◽  
Sensory Map ◽  
Thermal Stimuli ◽  
Classic Papers

This essay looks at two papers published by Ed Perl and co-workers that identified specifically nociceptive neurons in the periphery and superficial dorsal horn. Bessou P and Perl ER. Response of cutaneous sensory units with unmyelinated fibers to noxious stimuli. J Neurophysiol 32: 1025–1043 1969. Christensen BN and Perl ER. Spinal neurons specifically excited by noxious or thermal stimuli: marginal zone of the dorsal horn. J Neurophysiol 33: 293–307 1970.

Grouping of somatosensory neurons in the spinal cord and the gracile nucleus of the rat by cluster analysis

1994 ◽  
Vol 72 (6) ◽  
pp. 2590-2597 ◽  
Author(s):  
J. W. Leem ◽  
B. H. Lee ◽  
W. D. Willis ◽  
J. M. Chung
Keyword(s):  
Cluster Analysis ◽  
Dorsal Horn ◽  
Dynamic Range ◽  
High Threshold ◽  
Spinothalamic Tract ◽  
Wide Dynamic Range ◽  
Gracile Nucleus ◽  
Noxious Stimuli ◽  
Thermal Stimuli ◽  
Wide Dynamic Range Neurons

1. A set of 11 cutaneous stimuli defined previously to differentiate among different types of cutaneous sensory receptors in the rat hindpaw was also effective in differentially activating second-order sensory neurons in the dorsal horn and the gracile nucleus of rats. 2. All sampled units were responsive to more than 1 of the 11 stimuli. However, none responded to innocuous warming or cooling stimuli. Therefore further analysis was restricted to responses to nine of the selected stimuli. 3. Cluster analysis of the responses to nine selected innocuous and noxious mechanical stimuli and noxious thermal stimuli yielded seven classes that seemed functionally distinct from each other: a class of high-threshold neurons, three classes of convergent (wide dynamic range) neurons, a class of a mixture of poorly responsive neurons and neurons receiving Pacinian inputs, and two classes of low-threshold neurons. 4. High-threshold neurons responded predominantly to noxious mechanical and thermal stimuli and presumably received an input from both mechanically and thermally sensitive nociceptors. These cells were located in the dorsal horn, and some were spinothalamic tract cells. Wide dynamic range neurons were excited by innocuous and noxious stimuli, but better by noxious stimuli. These classes of cells were either in the dorsal horn (some were spinothalamic tract cells) or in the nucleus gracilis.(ABSTRACT TRUNCATED AT 250 WORDS)

Central sensitization following intradermal injection of capsaicin

1997 ◽  
Vol 20 (3) ◽  
pp. 471-471 ◽  
Author(s):  
William D. Willis
Keyword(s):  
Amino Acids ◽  
Substance P ◽  
Central Sensitization ◽  
Mechanical Allodynia ◽  
Excitatory Amino Acids ◽  
Intradermal Injection ◽  
Mechanical Hyperalgesia ◽  
Spinothalamic Tract ◽  
Nociceptive Neurons ◽  
Primary Hyperalgesia

Intradermal capsaicin in humans causes pain, primary hyperalgesia, and secondary mechanical hyperalgesia and allodynia. Parallel changes occur in the responses of primate spinothalamic tract cells and in rat behavior. Neurotransmitters that trigger secondary mechanical hyperalgesia and allodynia include excitatory amino acids and substance P. Secondary mechanical allodynia is actively maintained by central mechanisms. Our group has investigated mechanisms of central sensitization of nociceptive neurons by examining the responses to intradermal injection of capsaicin. These experiments are pertinent to issues raised by coderre & katz (sect. 2).

Presentation of Rapid Temperature Change Using Spatially Divided Hot and Cold Stimuli

2013 ◽  
Vol 25 (3) ◽  
pp. 497-505 ◽  
Author(s):  
Katsunari Sato ◽  
◽  
Takashi Maeno
Keyword(s):  
Temperature Change ◽  
Thermal Sensation ◽  
Spatial Summation ◽  
Single Stimulus ◽  
Experimental Results ◽  
Thermal Perception ◽  
Rapid Temperature ◽  
Temperature Sense ◽  
Thermal Stimuli

We propose a thermal display that presents a rapid temperature change using spatially divided hot and cold stimuli. The display exploits two characteristics of human thermal perception: spatial summation and the adapting temperature. Experimental results confirmed that users perceived separate individual thermal stimuli as a single stimulus because of spatial summation. Our thermal display successfully made the skin simultaneously more sensitive to both hot and cold stimuli by using spatially divided hot and cold stimuli, each of which separately adjusts the adapting temperature so that it enables users to perceive thermal sensation rapidly. The thermal display that we fabricated enabled users to perceive a different temperature sense by changing the temperature of hot and cold stimuli.

Effect of Systemic Morphine on the Responses of Convergent Neurons to Noxious Heat Stimuli Applied over Graded Surface Areas 

1999 ◽  
Vol 90 (4) ◽  
pp. 1129-1136 ◽  
Author(s):  
Olivier Gall ◽  
Didier Bouhassira ◽  
Djamel Chitour ◽  
Daniel Le Bars
Keyword(s):  
Spinal Cord ◽  
Spatial Summation ◽  
Adjacent Area ◽  
Neuronal Responses ◽  
Noxious Heat ◽  
Constant Intensity ◽  
Nociceptive Transmission ◽  
Surface Areas ◽  
Intravenous Morphine ◽  
Thermal Stimuli

Background Stimulus intensity is a major determinant of the antinociceptive activity of opiates. This study focused on the influence of the spatial characteristics of nociceptive stimuli, on opiate-induced depressions of nociceptive transmission at the level of the spinal cord. Methods Anesthetized rats were prepared to allow extracellular recordings to be made from convergent neurons in the lumbar dorsal horn. The effects of systemic morphine (1 and 10 mg/kg) were compared with those of saline for thermal stimuli of constant intensity, applied to the area of skin surrounding the excitatory receptive field (1.9 cm2) or to a much larger adjacent area (18 cm2). Results The responses (mean +/- SD) elicited by the 1.9-cm2 stimulus were not modified by 1 mg/kg intravenous morphine, although they were decreased by the 10-mg/kg dose (to 11+/-4% of control values compared with saline; P < 0.05). In contrast, when the 18-cm2 stimulus was applied, 1 mg/kg intravenous morphine produced a paradoxical facilitation of the neuronal responses (159+/-36% of control values; P < 0.05) and 10 mg/kg intravenous morphine resulted in a weaker depression of the responses (to 42+/-24% of control values; P < 0.05) than was observed with the smaller stimulus. Conclusions Doses of systemic morphine in the analgesic range for rats had dual effects on nociceptive transmission at the level of the spinal cord, depending on the surface area that was stimulated. Such effects are difficult to explain in terms of accepted pharmacodynamic concepts and may reflect an opioid-induced depression of descending inhibitory influences triggered by spatial summation.

scholarly journals Thermonociceptive interaction: interchannel pain modulation occurs before intrachannel convergence of warmth

2019 ◽  
Vol 121 (5) ◽  
pp. 1798-1808
Author(s):  
Antonio Cataldo ◽  
Elisa Raffaella Ferrè ◽  
Patrick Haggard
Keyword(s):  
Pain Intensity ◽  
Spatial Summation ◽  
Thermal Conditions ◽  
Laser Pulses ◽  
Middle Finger ◽  
Suppressive Effect ◽  
Inhibitory Effect ◽  
Pain Modulation ◽  
Perceived Pain ◽  
The Right

Nonnoxious warmth reduces both perceived pain intensity and the amplitude of EEG markers of pain. However, the spatial properties of thermonociceptive interaction, and the level of sensory processing at which it occurs, remain unclear. We investigated whether interchannel warmth-pain interactions occur before or after intrachannel spatial summation of warmth. Warm stimuli were applied to the fingers of the right hand. Their number and location were manipulated in different conditions. A concomitant noxious test pulse was delivered to the middle finger using a CO2 laser. We replicated the classical suppressive effect of warmth on both perceived pain intensity and EEG markers. Importantly, inhibition of pain was not affected by the location and the number of thermal stimuli, even though they increased the perceived intensity of warmth. Our results therefore suggest that the inhibitory effect of warmth on pain is not somatotopically organized. The results also rule out the possibility that warmth affects nociceptive processing after intrachannel warmth summation. NEW & NOTEWORTHY We used spatial summation of warmth as a model to investigate thermonociceptive interactions. Painful CO2 laser pulses were delivered during different thermal conditions. We found that warmth inhibited pain regardless of its location. Crucially, spatial summation of multiple warm stimuli did not further inhibit pain. These findings suggest that warmth-pain interaction occurs independently of or after spatial summation of warmth.

Spatial summation and spatial discrimination of pain sensation

Pain ◽  
2006 ◽  
Vol 126 (1) ◽  
pp. 123-131 ◽  
Author(s):  
Ruth Defrin ◽  
Ronit Givon ◽  
Netta Raz ◽  
Gideon Urca
Keyword(s):  
Spatial Summation ◽  
Spatial Discrimination ◽  
Pain Sensation
Sign in / Sign up

Export Citation Format

Share Document