Unmyelinated nociceptors of rat paraspinal tissues

1995 ◽  
Vol 73 (5) ◽  
pp. 1752-1762 ◽  
Author(s):  
G. M. Bove ◽  
A. R. Light
Keyword(s):  
Lumbar Spine ◽  
Intact Animal ◽  
Receptive Fields ◽  
Clinical Importance ◽  
Mechanical Stimuli ◽  
Peripheral Neuropathies ◽  
Deep Tissue ◽  
Surrounding Connective Tissue ◽  
Thermal Stimuli ◽  
Stimulation Of

1. We made recordings from rat dorsal root filaments to study unmyelinated afferent units (conduction velocity < or = 1.5 m/s) associated with deep paraspinal tissues of the dorsal sacrum and proximal tail. Data from 57 unmyelinated units were analyzed in 47 experiments. Receptive fields were identified in intact animals and then surgically isolated using microdissection. Units were characterized using mechanical, noxious chemical, and thermal stimuli. 2. These recordings revealed innervation of the nerve sheaths and surrounding connective tissue, muscles, tendons, and tissue apposed to the undersurface of the skin. No units were found with receptive fields directly on joint capsular tissue. The receptive fields of the units were often multiple and located in more than one tissue; 31 of 57 units showed convergence from different tissues. 3. The units with receptive fields on neurovascular bundles shared sensitivities with other deep tissue units described in this and other reports. These units may have clinical importance in pain due to peripheral neuropathies. 4. The units initially responded to strong mechanical stimulation of the intact animal and often to noxious stretch of the tail. Once surgically isolated, an individual unit's threshold to mechanical stimuli appeared lower. 5. Capsaicin (0.001%-0.1%) elicited responses in 81% (17 of 21) of the units tested. Bradykinin (20 micrograms/ml) elicited responses in 45% (10 of 22) of the units tested. Noxious cold (4-10 degrees C) and hot (55 degrees C) stimulation elicited discharges from 33% (5 of 15) and 25% (5 of 20) of the units tested, respectively. 6. The unmyelinated units had similar mechanical, chemical, and thermal sensitivities. These similarities and the observed convergence only allowed separation of units by the tissue in which the ending was found, and did not allow further classification. 7. The prevalence of background discharge suggested that many units were sensitized during the experiments. 8. The sensitivities of these paraspinal units were similar to those reported for other tissues. Because of the anatomic similarity of the paraspinal tissues of the proximal tail and the lumbar spine, the conclusions of the present study can be related to the lumbar spine. These afferent units are thought to participate in nociception from the deep paraspinal tissues.

Evidence for a central component in the sensitization of spinal neurons with joint input during development of acute arthritis in cat's knee

1990 ◽  
Vol 64 (1) ◽  
pp. 299-311 ◽  
Author(s):  
V. Neugebauer ◽  
H. G. Schaible
Keyword(s):  
Spinal Cord ◽  
Knee Joint ◽  
Mechanical Stimulation ◽  
Receptive Fields ◽  
Lumbar Spinal Cord ◽  
Mechanical Stimuli ◽  
Spinal Neurons ◽  
Deep Tissue ◽  
Lumbar Spinal ◽  
Stimulation Of

1. In the spinalized cat, nociceptive spinal neurons with knee input show enhanced responses to mechanical stimulation of that joint once an inflammation has developed in the knee. Enhanced responses may result from increased afferent inflow as well as from modifications of the nociceptive processing within the spinal cord. To examine the significance of these components, we tested in 30 chloralose-anesthetized, spinalized cats whether, during development of arthritis, changes of responsiveness in spinal neurons are restricted to stimulation of the inflamed joint or whether responsiveness in these neurons is altered in general. While continuously recording from a neuron, we injected kaolin and carrageenan into one knee and tested the responses to mechanical stimuli applied to the joint and to regions adjacent to and remote from the knee during the developing arthritis. In addition, in six cats we monitored the neurons' responses to electrical stimulation of the sural nerves and the rostral lumbar spinal cord. 2. Of 32 neurons in laminae VI, VII, and VIII of the lumbar spinal cord, 15 ascending and eight nonascending cells were driven by mechanical stimulation of one or both knee joint(s). Nine of these were nociceptive specific (NS), responding exclusively or predominantly to noxious compression of the knee and other deep tissue, and 12 were wide-dynamic-range (WDR) cells with graded responses to gentle and noxious stimuli applied to the knee joint(s), deep tissue, and skin. Two neurons with high ongoing discharges had some excitatory joint input but showed marked inhibition by most stimuli used (INH neurons). The majority of the neurons had receptive fields on both legs. Nine of the 32 neurons had no input from the knee(s). 3. All 23 neurons with joint input became sensitive or more responsive to movements and gentle compression of the inflamed knee once the inflammation had developed. In general, these neurons also showed enhanced responses to compression of the adjacent muscles in thigh and lower leg. In 20 neurons, response properties were even altered for stimuli applied to regions remote from the inflamed joint, including the contralateral leg in 18 cases. We found expansion of initially restricted receptive fields (mainly in NS cells), enhancement of preexisting responses, and/or lowering of threshold to mechanical stimuli applied to these regions; few neurons developed inhibitory reactions.(ABSTRACT TRUNCATED AT 400 WORDS)

Responses of neurons in the lateral cervical nucleus of the cat to noxious cutaneous stimulation

1987 ◽  
Vol 57 (6) ◽  
pp. 1686-1704 ◽  
Author(s):  
K. C. Kajander ◽  
G. J. Giesler
Keyword(s):  
Receptive Fields ◽  
Noxious Stimulation ◽  
Mechanical Stimuli ◽  
Cutaneous Stimulation ◽  
Nociceptive Neurons ◽  
Nociceptive Responses ◽  
Lateral Cervical Nucleus ◽  
Noxious Mechanical Stimulation ◽  
Thermal Stimuli ◽  
Stimulation Of

The majority of neurons at the origin of the spinocervical tract are driven by noxious stimulation of their receptive fields. Surprisingly, previous studies have encountered only a small percentage of nociceptive neurons within the terminus of the spinocervical tract, the lateral cervical nucleus (LCN). To determine if previous reports have underestimated the proportion of nociceptive LCN neurons, 129 neurons within the nucleus were physiologically identified and examined in cats prepared using three different methods. Fifty-nine percent of the neurons studied in unanesthetized cats that were decerebrated and spinalized responded either differentially or exclusively to noxious mechanical stimulation of the skin within discrete receptive fields. LCN neurons also gave accelerating responses to increasingly more intense noxious thermal stimuli. LCN neurons are, therefore, capable of coding both the intensity and location of noxious stimuli. Only 6% of LCN neurons responded to noxious cutaneous stimuli in unanesthetized, decerebrated cats in which the spinal cord was intact. Only 4% of LCN neurons in intact urethan-anesthetized cats were driven by noxious stimulation. Several previous studies of the LCN have been performed in cats that were deeply anesthetized with barbiturates. Therefore, the effects of barbiturates on the nociceptive responses of LCN neurons were determined. Subanesthetic doses of intravenously administered barbiturates reduced or eliminated the responses of nociceptive LCN neurons to noxious thermal stimuli in decerebrated and spinalized cats. Responses to innocuous mechanical stimuli by these neurons were not blocked by barbiturates. Nociceptive LCN neurons in decerebrated and spinalized cats were somatotopically organized. Neurons with forelimb receptive fields were located in the ventromedial half of the LCN; neurons with hindlimb receptive fields were located in the dorsolateral half of the nucleus. This report and previous studies of the spinocervical tract suggest that the spinocervicothalamic pathway is capable of playing an important role in nociception.

Changes in the response properties of neurons in the ventroposterior lateral thalamic nucleus of the raccoon after peripheral deafferentation

1996 ◽  
Vol 75 (6) ◽  
pp. 2441-2450 ◽  
Author(s):  
D. D. Rasmusson
Keyword(s):  
Receptive Field ◽  
Thalamic Nucleus ◽  
Receptive Fields ◽  
Field Size ◽  
Mechanical Stimuli ◽  
Sensory Pathways ◽  
Average Latency ◽  
Somatotopic Map ◽  
Almost All ◽  
Stimulation Of

1. Single neurons in the ventroposterior lateral thalamic nucleus were studied in 10 anesthetized raccoons, 4 of which had undergone amputation of the fourth digit 4-5 mo before recording. Neurons with receptive fields on the glabrous skin of a forepaw digit were examined in response to electrical stimulation of the “on-focus” digit that contained the neuron's receptive field and stimulation of an adjacent, “off-focus” digit. 2. In normal raccoons all neurons responded to on-focus stimulation with an excitation at a short latency (mean 13 ms), whereas only 63% of the neurons responded to off-focus digit stimulation. The off-focus responses had a longer latency (mean 27.2 ms) and a higher threshold than the on-focus responses (800 and 452 microA, respectively). Only 3 of 32 neurons tested with off-focus stimulation had both a latency and a threshold within the range of on-focus values. Inhibition following the excitation was seen in the majority of neurons with both types of stimulation. 3. In the raccoons with digit removal, the region of the thalamus that had lost its major peripheral input (the “deafferented” region) was distinguished from the normal third and fifth digit regions on the basis of the sequence of neuronal receptive fields within a penetration and receptive field size as described previously. 4. Almost all of the neurons in the deafferented region (91%) were excited by stimulation of one or both adjacent digits. The average latency for these responses was shorter (15.3 ms) and the threshold was lower than was the case with off-focus stimulation in control animals. These values were not significantly different from the responses to on-focus stimulation in the animals with digit amputation. 5. These results confirm that reorganization of sensory pathways can be observed at the thalamic level. In addition to the changes in the somatotopic map that have been shown previously with the use of mechanical stimuli, the present paper demonstrates an improvement in several quantitative measures of single-unit responses. Many of these changes suggest that this reorganization could be explained by an increased effectiveness of preexisting, weak connections from the off-focus digits; however, the increase in the proportion of neurons responding to stimulation of adjacent digits may indicate that sprouting of new connections also occurs.

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.

scholarly journals Response characteristics of pruriceptive and nociceptive trigeminoparabrachial tract neurons in the rat

2015 ◽  
Vol 113 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Nico A. Jansen ◽  
Glenn J. Giesler
Keyword(s):  
Discharge Rate ◽  
Receptive Fields ◽  
Behavioral Responses ◽  
Spike Timing ◽  
Mustard Oil ◽  
Mechanical Stimuli ◽  
Firing Rates ◽  
Response Characteristics ◽  
Mapping Techniques ◽  
Thermal Stimuli

We tested the possibility that the trigeminoparabrachial tract (VcPbT), a projection thought to be importantly involved in nociception, might also contribute to sensation of itch. In anesthetized rats, 47 antidromically identified VcPbT neurons with receptive fields involving the cheek were characterized for their responses to graded mechanical and thermal stimuli and intradermal injections of pruritogens (serotonin, chloroquine, and β-alanine), partial pruritogens (histamine and capsaicin), and an algogen (mustard oil). All pruriceptive VcPbT neurons were responsive to mechanical stimuli, and more than half were additionally responsive to thermal stimuli. The majority of VcPbT neurons were activated by injections of serotonin, histamine, capsaicin, and/or mustard oil. A subset of neurons were inhibited by injection of chloroquine. The large majority of VcPbT neurons projected to the ipsilateral and/or contralateral external lateral parabrachial and Kölliker-Fuse nuclei, as evidenced by antidromic mapping techniques. Analyses of mean responses and spike-timing dynamics of VcPbT neurons suggested clear differences in firing rates between responses to noxious and pruritic stimuli. Comparisons between the present data and those previously obtained from trigeminothalamic tract (VcTT) neurons demonstrated several differences in responses to some pruritogens. For example, responses of VcPbT neurons to injection of serotonin often endured for nearly an hour and showed a delayed peak in discharge rate. In contrast, responses of VcTT neurons endured for roughly 20 min and no delayed peak of firing was noted. Thus the longer duration responses to 5-HT and the delay in peak firing of VcPbT neurons better matched behavioral responses to stimulation in awake rats than did those of VcTT neurons. The results indicate that VcPbT neurons may have important roles in the signaling of itch as well as pain.

Neuronal and behavioural responses in rats during noxious stimulation of the tail

1977 ◽  
Vol 197 (1127) ◽  
pp. 169-194 ◽  
Keyword(s):  
Dorsal Horn ◽  
Receptive Fields ◽  
Temperature Response ◽  
Threshold Temperature ◽  
Noxious Stimulation ◽  
Mechanical Stimuli ◽  
Response Curves ◽  
Ventrobasal Nucleus ◽  
Behavioural Experiments ◽  
Stimulation Of

In rats anaesthetized with urethane, extracellular unit activity has been recorded from neurones in the central nervous system during noxious stimulation of the tail. Accurately graded and sustained stimulation was achieved by immersing the whole tail in water at controlled temperatures. Neurones were found chiefly in the marginal layers of the dorsal horn near the entry of the dorsal roots supplying the tail and in the ventrobasal nucleus of the thalamus; a few neurones were also found in the somatosensory cortex. Both dorsal horn units and thalamic units showed very similar responses as the tail temperature was gradually raised. At 42°C there was an increase in firing rate which rose sharply with increasing temperatures to reach a maximum at 46°C. At higher temperatures activ­ity declined and at temperatures above 50°C was largely extinguished. The temperature-response curves were bell-shaped. The decline in activity depended on temperature and not on time: sustained firing for many minutes was seen when temperature was at or just below the peak of the bell-shaped curve. The dorsal horn and thalamic cells also responded to noxious mechanical stimulation of the tail. The receptive fields at both levels were similar, being variable in size, often bilateral and sometimes covering the whole tail. None of the central neurones showed any response to noxious stimulation other than on the tail; neither did they respond to movement of the tail nor to light mechanical stimuli applied to the tail or elsewhere. In behavioural experiments conscious rats had their tails exposed to water at various temperatures. The rats lifted their tails from the water at a threshold temperature of 43.7 ± 0.6°C, i. e. just above the threshold for the central nociceptive neurones. The findings are compatible with a specific nociceptive pathway ascending to the ventrobasal thalamus.

Responses of neurons in primate ventral posterior lateral nucleus to noxious stimuli

1980 ◽  
Vol 43 (6) ◽  
pp. 1594-1614 ◽  
Author(s):  
D. R. Kenshalo ◽  
G. J. Giesler ◽  
R. B. Leonard ◽  
W. D. Willis
Keyword(s):  
Receptive Fields ◽  
Dorsal Column ◽  
Sensory Cortex ◽  
Noxious Stimulation ◽  
Mechanical Stimuli ◽  
Thalamic Neuron ◽  
Noxious Heat ◽  
Thalamic Neurons ◽  
Noxious Stimuli ◽  
Stimulation Of

1. Recordings were made from the caudal part of the ventral posterior lateral (VPLc) nucleus of the thalamus in anesthetized macaque monkeys. In additon to many neurons that responded only to weak mechanical stimuli, scattered neurons were found that responded to both innocuous and noxious stimulation or just to noxious stimulation of the skin. A total of 73 such neurons were examined in 26 animals. 2. Noxious stimuli included strong mechanical stimuli (pressure, pinch, and squeezing with forceps) and graded noxious heat (from 35 degrees C adapting temperature to 43, 45, 47, and 50 degrees C). The responses of the VPLc neurons increased progressively with greater intensities of noxious stimulation. The stimulus-response function when noxious heat stimuli were used was a power function with an exponent greater than one. 3. Repetition of the noxious heat stimuli revealed sensitization of the responses of the thalamic neurons to such stimuli. The threshold for a response to noxious heat was lowered, and the responses to supra-threshold noxious heat stimuli were enhanced. 4. The responses of VPLc neurons to noxious heat stimuli adapted after reaching a peak discharge frequency. The rate of adaptation was slower for a stimulus of 50 degrees C than for one of 47 degrees C. 5. For the six neurons tested, responses to noxious heat were dependent on pathways ascending in the ventral part of the lateral funiculus contralateral to the receptive field (ipsilateral to the thalamic neuron). In two cases, the input to the thalamic neurons from axons of the dorsal column was also conveyed by way of a crossed pathway in the opposite ventral quadrant. In another case, access to the thalamic neuron by way of ascending dorsal column fibers was demonstrated. 6. The thalamic neurons had restricted contralateral receptive fields that were somatotopically organized. Neurons with receptive fields on the hindlimb were in the lateral part of the VPLc nucleus, whereas neurons with receptive fields on the forelimb were in medial VPLc. 7. Ninety percent of the VPLc neurons tested that responded to noxious stimuli could be activated antidromically by stimulation of the surface of SI sensory cortex. It was possible to confirm that many of these cells project to the SI sensory cortex by using microstimulation. Successful microstimulation points were either within the SI cortex or in the white matter just beneath the cortex. 8. We conclude that some neurons in the VPLc nucleus are capable of signaling noiceptive stimuli. The nociceptive information appears to reach these cells through the ventral part of the lateral funiculus on the side contralateral to the receptive field, presumably by way of the spinothalamic tract. The VPLc cells are somatotopically organized, and they are thalamocortical neurons that project to the VPLc nucleus and SI cortex play a role in nociception.

Processing of Nociceptive Mechanical and Thermal Information in Central Amygdala Neurons With Knee-Joint Input

2002 ◽  
Vol 87 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Volker Neugebauer ◽  
Weidong Li
Keyword(s):  
Knee Joint ◽  
Mechanical Stimulation ◽  
Receptive Fields ◽  
Central Nucleus ◽  
Response Functions ◽  
Central Amygdala ◽  
Deep Tissue ◽  
Stimulus Response ◽  
Noxious Mechanical Stimulation ◽  
Stimulation Of

Pain has a strong emotional dimension, and the amygdala plays a key role in emotionality. The processing of nociceptive mechanical and thermal information was studied in individual neurons of the central nucleus of the amygdala, the target of the spino-parabrachio-amygdaloid pain pathway and a major output nucleus of the amygdala. This study is the first to characterize nociceptive amygdala neurons with input from deep tissue, particularly the knee joint. In 46 anesthetized rats, extracellular single-unit recordings were made from 119 central amygdala neurons that were activated orthodromically by electrical stimulation in the lateral pontine parabrachial area and were tested for receptive fields in the knee joints. Responses to brief mechanical stimulation of joints, muscles, and skin and to cutaneous thermal stimuli were recorded. Receptive-field sizes and thresholds were mapped and stimulus-response functions constructed. Neurons in the central nucleus of the amygdala with excitatory input from the knee joint ( n = 62) typically had large symmetrical receptive fields in both hindlimbs or in all four extremities and responded exclusively or preferentially to noxious mechanical stimulation of deep tissue ( n = 58). Noxious mechanical stimulation of the skin excited 30 of these neurons; noxious heat activated 21 neurons. Stimulus-response data were best fitted by a sigmoid nonlinear regression model rather than by a monotonically increasing linear function. Another 15 neurons were inhibited by noxious mechanical stimulation of the knee joint and other deep tissue. Fifteen neurons had no receptive field in the knee but responded to noxious stimulation of other body areas; 27 nonresponsive neurons were not activated by natural somesthetic stimulation. Our data suggest that excitation is the predominant effect of brief painful stimulation of somatic tissue on the population of central amygdala neurons with knee joint input. Their large symmetrical receptive fields and sigmoid rather than monotonically increasing linear stimulus-response functions suggest a role of nociceptive central amygdala neurons in other than sensory-discriminative aspects of pain.

The primate spinocervicothalamic pathway: responses of cells of the lateral cervical nucleus and spinocervical tract to innocuous and noxious stimuli

1988 ◽  
Vol 59 (3) ◽  
pp. 861-885 ◽  
Author(s):  
J. W. Downie ◽  
D. G. Ferrington ◽  
L. S. Sorkin ◽  
W. D. Willis
Keyword(s):  
Conduction Velocity ◽  
Dynamic Range ◽  
Receptive Fields ◽  
Glabrous Skin ◽  
Mechanical Stimuli ◽  
Spinothalamic Tract ◽  
Sinusoidal Vibration ◽  
Antidromic Activation ◽  
Lateral Cervical Nucleus ◽  
Stimulation Of

1. The response properties of neurons of the spinocervicothalamic pathway were studied in anesthetized macaque monkeys. Graded innocuous and noxious mechanical stimuli, including sinusoidal vibration and thermal pulses, were applied to the cutaneous receptive fields. 2. Forty-nine cells in the lateral cervical nucleus (LCN) were identified by antidromic activation from the ventral posterior lateral (VPL) nucleus of the contralateral thalamus. Twelve spinocervical tract (SCT) cells in the lumbosacral enlargement of the spinal cord were identified by antidromic activation from stimulation of the ipsilateral dorsolateral funiculus below C3 but not above C1. 3. Latencies for antidromic activation of LCN neurons averaged 2.3 ms, corresponding to a mean conduction velocity of approximately 17 m/s. Mean latency for orthodromic activation of LCN neurons following electrical stimulation of peripheral nerves was 12.6 ms. Overall mean conduction velocity for the monkey spinocervicothalamic pathway was estimated to be 29 m/s. 4. Most LCN cells had receptive fields on hairy skin, but some had input from glabrous skin and a few had subcutaneous fields. The receptive fields of most SCT cells had a glabrous skin component. Receptive fields tended to be smaller for SCT than LCN cells even for fields on a comparable part of the distal hindlimb. 5. Based on their responses to a series of mechanical stimuli (brushing, pressure, pinch, and squeeze), LCN and SCT cells were classified as low-threshold (LT), wide dynamic range (WDR), or high-threshold (HT) neurons. Most of the cells were in the LT or WDR classes. Thus the spinocervicothalamic pathway in the monkey differs from the spinothalamic tract (STT), in that STT cells are generally of the WDR or HT classes. 6. With the use of discriminant analysis, LCN and SCT neurons were allocated to categories determined from a k-means cluster analysis of the responses of 318 STT cells. The LCN and SCT neurons were in different proportions in the various categories than were STT cells, suggesting differences in the signaling properties of the spinocervicothalamic and spinothalamic paths. 7. Innocuous steady indentation of the skin failed to excite any of the neurons tested. Thus no positive evidence was obtained for an input to LCN neurons from slowly adapting mechanoreceptors. 8. Sinusoidal vibratory stimuli were used to test the ability of LCN and SCT neurons to follow repeated innocuous mechanical stimuli. Vibration at 10 Hz and an amplitude of 100 micron resulted in repetitive discharges in most LCN neurons and half the SCT neurons tested; many LCN neurons had thresholds below 25 micron.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Central mechanisms of vascular headaches

1991 ◽  
Vol 69 (5) ◽  
pp. 652-658 ◽  
Author(s):  
J. O. Dostrovsky ◽  
K. D. Davis ◽  
K. Kawakita
Keyword(s):  
Electrical Stimulation ◽  
Receptive Fields ◽  
Middle Meningeal Artery ◽  
Trigeminal System ◽  
Published Data ◽  
Mechanical Stimuli ◽  
Sagittal Sinus ◽  
Ganglion Neurons ◽  
Meningeal Artery ◽  
Stimulation Of

The intracranial blood vessels supplying the dura and brain are innervated by sensory afferents from the trigeminal nerve. These fibers are believed to be responsible for conveying the pain associated with vascular head pain such as migraines. This paper reviews recently published data describing the existence of neurons within the cat trigeminal nucleus and thalamus that respond to electrical stimulation of the middle meningeal artery and superior sagittal sinus. Almost all of these neurons receive convergent input from the facial skin and most of the receptive fields include the periorbital region. On the basis of their cutaneous inputs, most of the neurons are classified as nociceptive. The characteristics of these cerebrovascular-activated neurons are consistent with their role in mediating vascular head pains and with the typical referral of such pains in man to the orbital region. This paper also presents preliminary results of recordings from rat trigeminal ganglion neurons activated by electrical stimulation of the middle meningeal artery and sagittal sinus. The latencies of activation of these neurons are indicative of conduction in slowly conducting myelinated axons and in unmyelinated axons. Some of the neurons could also be activated by mechanical stimuli applied to the vessels.Key words: headache, pain, trigeminal system, somatosensory, thalamus.

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