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Journal ArticleDOI

Spinal neurons specifically excited by noxious or thermal stimuli: marginal zone of the dorsal horn.

01 Mar 1970-Journal of Neurophysiology (American Physiological Society)-Vol. 33, Iss: 2, pp 293-307
TL;DR: HIGH-THRESHOLD MECHANORECEPTORS and their centrally projecting myelinated fibers make up a functionally distinct group of cutaneous sensory units that have been suggested as part of the afferent apparatus for pain resulting from mechanical damage to the skin.
Abstract: HIGH-THRESHOLD MECHANORECEPTORS and their centrally projecting myelinated fibers make up a functionally distinct group of cutaneous sensory units that have been suggested as part of the afferent apparatus for pain resulting from mechanical damage to the skin (3, 17). The argument for their relation to pain was based on two points: 1) the ability of such afferent elements, unique among those with medullated fibers, to provide signals differentiating noxious from innocuous mechanical events affecting the skin; and 2) the well-established correlation between pain and activity in thin myelinated afferent fibers
Citations
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Journal ArticleDOI
TL;DR: A review of the basic neuroscience processes of pain (the bio part of biopsychosocial, as well as the psychosocial factors, is presented) and on the development of new technologies, such as brain imaging, that provide new insights into brain-pain mechanisms.
Abstract: The prevalence and cost of chronic pain is a major physical and mental health care problem in the United States today. As a result, there has been a recent explosion of research on chronic pain, with significant advances in better understanding its etiology, assessment, and treatment. The purpose of the present article is to provide a review of the most noteworthy developments in the field. The biopsychosocial model is now widely accepted as the most heuristic approach to chronic pain. With this model in mind, a review of the basic neuroscience processes of pain (the bio part of biopsychosocial), as well as the psychosocial factors, is presented. This spans research on how psychological and social factors can interact with brain processes to influence health and illness as well as on the development of new technologies, such as brain imaging, that provide new insights into brain-pain mechanisms.

2,566 citations


Cites background from "Spinal neurons specifically excited..."

  • ...(2000) Spinal cord hemisection Christensen et al. (1996); Christensen & Hulsebosch (1997a, 1997b) Injection of quisqualic acid Yezierski & Park (1993); Yezierski et al. (1993, 1998) Injection of kainate LaBuda et al. (2000) Ischemia Hao, Xu, Yu, et al. (1991); Hao, Xu, Aldskogius, et al. (1991); Hao, Xu, Yu, et al. (1992); Xu et al. (1992); Hao, Xu, Aldskogius, et al....

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  • ...The finding of the superficial laminae of the spinal cord for nociception demonstrated that these neurons responded to mechanical and thermal nociceptive inputs in lamina I (B. N. Christensen & Perl, 1970) and II (Kumazawa & Perl, 1978)....

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  • ...(2000) Spinal cord hemisection Christensen et al. (1996); Christensen & Hulsebosch (1997a, 1997b) Injection of quisqualic acid Yezierski & Park (1993); Yezierski et al. (1993, 1998) Injection of kainate LaBuda et al. (2000) Ischemia Hao, Xu, Yu, et al. (1991); Hao, Xu, Aldskogius, et al. (1991); Hao, Xu, Yu, et al....

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  • ...(2000) Spinal cord hemisection Christensen et al. (1996); Christensen & Hulsebosch (1997a, 1997b) Injection of quisqualic acid Yezierski & Park (1993); Yezierski et al. (1993, 1998) Injection of kainate LaBuda et al. (2000) Ischemia Hao, Xu, Yu, et al. (1991); Hao, Xu, Aldskogius, et al. (1991); Hao, Xu, Yu, et al. (1992); Xu et al. (1992); Hao, Xu, Aldskogius, et al. (1992) Sciatic Injection of zymosan Gazda et al. (2001); Chacur et al....

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  • ...(2000) Spinal cord hemisection Christensen et al. (1996); Christensen & Hulsebosch (1997a, 1997b) Injection of quisqualic acid Yezierski & Park (1993); Yezierski et al. (1993, 1998) Injection of kainate LaBuda et al. (2000) Ischemia Hao, Xu, Yu, et al. (1991); Hao, Xu, Aldskogius, et al....

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Journal ArticleDOI
TL;DR: Using positron emission tomography, it is found contralateral activity correlated with graded cooling stimuli only in the dorsal margin of the middle/posterior insula in humans, which supports the proposal that central pain results from loss of the normal inhibition of pain by cold.
Abstract: Temperature sensation is regarded as a submodality of touch, but evidence suggests involvement of insular cortex rather than parietal somatosensory cortices. Using positron emission tomography (PET), we found contralateral activity correlated with graded cooling stimuli only in the dorsal margin of the middle/posterior insula in humans. This corresponds to the thermoreceptive- and nociceptive-specific lamina I spinothalamocortical pathway in monkeys, and can be considered an enteroceptive area within limbic sensory cortex. Because lesions at this site can produce the post-stroke central pain syndrome, this finding supports the proposal that central pain results from loss of the normal inhibition of pain by cold. Notably, perceived thermal intensity was well correlated with activation in the right (ipsilateral) anterior insular and orbitofrontal cortices.

950 citations


Cites background from "Spinal neurons specifically excited..."

  • ...Innocuous primary afferent (Aδ ‘cool’ and C ‘warm’) thermoreceptors innervating skin and deep tissues terminate in the superficial spinal (and trigeminal) dorsal horn, where a unique population of lamina I spinothalamic neurons is thermoreceptive-specific and morphologically distinc...

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Journal ArticleDOI
TL;DR: In the literature, there are some contradictions with respect to the stimulus modalities to which hyperalgesia and sensitization occur and this contradiction should spawn further investigations into the mechanical response properties of nociceptors and into the molecular mechanisms of heat sensitization.

867 citations

Journal ArticleDOI
TL;DR: Results suggest that there is a highly specialized central projection of primary afferent endings which is related to sensory function and not to fiber diameter, and which receives direct input from cutaneous receptors transmitting activity initiated by innocuous stimulation.
Abstract: Single primary afferent myelinated fibers from cutaneous receptors of cat and monkey were functionally identified by recording from the spinal cord with micropipettes filled with horseradish peroxidase (HRP). Relatively slowly conducting fibers (less than 40 m/sec) from high threshold mechanoreceptors (mechanical nociceptors) and two types of low threshold mechanoreceptor (D-hair and field) were selected for staining. Iontophoresis of the HRP and subsequent histochemical reaction stained the axons recorded from and their collaterals, including terminations, for several millimeters. The termination patterns in the two species proved essentially identical. Ipsilaterally, the mechanical nociceptor fibers terminated principally in the dorsal horn's marginal zone and in the ventral parts of the nucleus proprius (lamina V in the cat). Some of these nociceptors also had terminals in the midline just dorsal to the central canal, contralaterally in the marginal zone, and at the base of the opposite nucleus proprius. In contrast, the D-hair primary afferent axons terminated in the dorsal part of the nucleus proprius overlapping into the innermost portion of the substantia gelatinosa. The field receptor fibers terminated predominantly in the middle part of the nucleus proprius. These results suggest that there is a highly specialized central projection of primary afferent endings which is related to sensory function and not to fiber diameter. The marginal zone and most dorsal parts of the substantia gelatinosa receive direct projections from cutaneous nociceptors but do not have direct input from cutaneous receptors transmitting activity initiated by innocuous stimulation.

783 citations

References
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Journal ArticleDOI
Bror Rexed1

1,575 citations


Additional excerpts

  • ...These results were taken to indicate that the dorsal horn marginal layer, Rexed’s lamina I (20), represents a specialized sensory nucleus containing neurons important for nociception and for detection of thermal changes in the skin....

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Journal ArticleDOI
TL;DR: In an attempt to learn more about the range of behavior associated with the terminals of cutaneous C fibers, a number of randomly sele,cted units were surveyed for responses to a variety of graded stimuli.
Abstract: the concept that sense organs of the skin with unmyelinated (C) fibers have widely varying functional characteristics. In the mammal, a large proportion of such sensory units are excited by gentle mechanical stimuli (8, 16, 34) and by transient cooling (9). Others are described as responding best to small temperature changes (13, 18) and some are reported to have elevated thresholds for various or all stimuli (14, 15, 18, 32). Studies proposing large and important differences between various afferent units with C fibers have drawn conclusions from a small or highly selected population and no view has been provided of the way in which these differences fit into the spectrum presented by the sensory structures from a given skin region. Such information seems essential for the understanding of somatic sensation inasmuch as unmyelinated fibers far outnumber myelinated fibers in the afferent nerves from the skin. In particular, unmyelinated afferent fibers are generally agreed to have some causal relation to pain and its associated reactions (3, 6, 7, 25). A crucial issue in hypotheses correlating afferent activity to pain is whether the underlying mechanisms are set off by impulses from sensory structures responding only to noxious stimuli (i.e., intense enough to threaten or (cause tissue damage) or whether they are triggered by special patterns of discharge from nonspecific afferent units (25). In an attempt to learn more about the range of behavior associated with the terminals of cutaneous C fibers, we surveyed a number of randomly sele,cted units for responses to a variety of graded stimuli. The results point out that a large proportion of

1,022 citations


"Spinal neurons specifically excited..." refers background or methods in this paper

  • ...Spinal units responding to strong mechanical stimuli and to noxious heat apparently received an excitatory input from both the high-threshold mechanoreceptors with myelinated afferent fibers (3) and the polymodal nociceptors with unmyelinated afferent fibers (1)....

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  • ...for activation; apparently they were subject to convergence from both the high-threshold mechanoreceptors with myelinated fibers and polymodal nociceptors with unmyelinated fibers (1)....

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  • ...Skin stimuli were delivered using the various devices described in previous publications (1, 3)....

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Journal ArticleDOI
TL;DR: The characteristics of receptors from the hairy skin of the hind limb of cat were studied by recording from single primary afferent fibres with fine micropipettes with distinctive features of 513 fibres conducting under 51 m/sec.
Abstract: 1. The characteristics of receptors from the hairy skin of the hind limb of cat were studied by recording from single primary afferent fibres with fine micropipettes. The distinctive features of 513 fibres conducting under 51 m/sec are described. 2. Seventy-four fibres conducting between 6 and 37 m/sec were classified as nociceptors because they responded only to damaging mechanical stimulation of the skin. These fibres responded maximally to pinching the skin with a serrated forceps or to cutting the skin. Noxious heat, noxious cold, acid applied to the receptive field and bradykinin injected into skin cuts did not evoke discharges from such receptors. Typically their receptive fields were 2-5 cm long by 1-2·5 cm wide and consisted of responsive spots (under 1 mm diameter) separated by unresponsive areas. There was a tendency for the most slowly conducting fibres so classified to be the least sensitive. 3. Other afferent fibres had receptive fields similar to the nociceptors; however, they were excited by substantial but not noxious mechanical deformation. Their conduction velocities overlapped those of the nociceptors and extended upwards to 51 m/sec; the most rapidly conducting fibres tended to be the most sensitive to mechanical stimuli. These insensitive mechanoreceptors or moderate pressure receptors adapted more slowly than the nociceptors. 4. The majority of fine myelinated axons originated from hair receptors and had conduction velocities concentrated between 14 and 22 m/sec. 5. The possible relation of these observations to pain and reactions typical of pain is considered.

594 citations


"Spinal neurons specifically excited..." refers background or methods in this paper

  • ...gested as part of the afferent apparatus for pain resulting from mechanical damage to the skin (3, 17)....

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  • ...studies on the posterior femoral cutaneous and sural nerves (3, 4), some high-threshold mechanoreceptors may have receptive terminals distributed over as large an area as that innervated by a coccygeal segment....

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  • ...One group responded in a way indicating an effective drive solely from the myelinated afferent fibers of high-threshold mechanoreceptors (3); they responded only to strong or frankly noxious mechanical stimulation of the skin....

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  • ...Spinal units responding to strong mechanical stimuli and to noxious heat apparently received an excitatory input from both the high-threshold mechanoreceptors with myelinated afferent fibers (3) and the polymodal nociceptors with unmyelinated afferent fibers (1)....

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  • ...Skin stimuli were delivered using the various devices described in previous publications (1, 3)....

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Journal ArticleDOI
TL;DR: The functional characteristics of cutaneous receptors in the squirrel monkey were determined by recording discharges of single myelinated afferent fibres in peripheral nerves with micro‐electrodes or from fine filaments prepared by dissection.
Abstract: 1. The functional characteristics of cutaneous receptors in the squirrel monkey were determined by recording discharges of single myelinated afferent fibres in peripheral nerves with micro-electrodes or from fine filaments prepared by dissection. One hundred and sixty-nine fibres of the posterior femoral cutaneous nerve and 209 of the superficial radial nerve with conduction velocities between 4 and 88 m/sec were classified according to the nature of the most effective stimulus, discharge characteristics, adaptation rate and organization of the receptive field.2. Twenty per cent of the fibres innervating either hairy or glabrous skin required strong mechanical stimuli for activation; thresholds ranged from moderate to overtly damaging pressures. This class showed little or no sensitivity to thermal changes including noxious heat. Their receptive fields consisted of numerous, mechanically-excitable points or spots. All such fibres gave higher impulse frequencies to noxious than to innocuous mechanical stimuli and a large fraction were considered to be nociceptors because they responded only to noxious deformation. The conduction velocities of nociceptors were distributed between 5 and 28 m/sec.3. All but a few of the other fibres encountered responded vigorously to innocuous stimuli and were readily identified as corresponding to one of the receptor types known to exist in either the primate or the cat. These sensitive receptors were systematically tested by intense cutaneous stimuli; their response to injurious stimuli always could be mimicked by innocuous ones.4. Therefore, in the primate a particular class of slowly-conducting myelinated fibres is partially responsible for signalling mechanically-induced cutaneous damage. The probable relation between such afferent fibres and certain kinds of cutaneous pain is explored.

315 citations


"Spinal neurons specifically excited..." refers background in this paper

  • ...gested as part of the afferent apparatus for pain resulting from mechanical damage to the skin (3, 17)....

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