Medullary Dorsal Horn Neurons Research Articles

Rapid transneuronal destruction following peripheral nerve transection in the medullary dorsal horn is enhanced by strychnine, picrotoxin and bicuculline

The effects of systemic administration of strychnine (1 mg/kg), picrotoxin (0.5 mg/kg) and bicuculline (2 mg/kg) on acute transsynaptic destruction of medullary dorsal horn neurons following transection of the inferior alveolar nerve were assessed in rats. Single intraperitoneal injections of the above drugs were given without, l min before or l min after the nerve transection. The effect of transection without drug administration was also examined. Eighteen hours after nerve transection without drug, approximately 7 dark neurons were found in a single toluidine blue stained l μm section of the rostral medullary dorsal horn ipsilateral to the nerve transection. Administration of the drugs l min before the nerve transection significantly increased the number of dark neurons in a single section to about 17 (strychnine), 46 (picrotoxin) and 20 (bicuculline). These dark neurons were found mainly in the dorsal half of medullary dorsal horn. Delivery of any of the drugs l min after the nerve transection did not increase the number of dark neurons. The data thus indicate that the transneuronal effect of transection of the nerve was enhanced by antagonism of glycinergic and GABAergic inhibition of dorsal horn neurons. In view of the short latency and duration of transsynaptic destructive activity, a massive injury discharge of primary afferent neurons and the subsequent release of excitatory neurotransmitters appear to be the direct cause of convulsant-enhanced rapid transsynaptic destruction which follows the peripheral nerve transection.

Task-related responses of monkey medullary dorsal horn neurons.

Medullary dorsal horn neurons with trigeminal sensory properties have been previously shown to have additional responses associated with cues relevant to the successful execution of a behavioral task. These "task-related" responses were evoked by environmental cues but were independent of the specific stimulus parameters. We have examined further the characteristics of task-related responses in medullary dorsal horn neurons of three monkeys. Single-unit activity was recorded while the monkeys were performing behavioral tasks that required them to discriminate thermal or visual stimuli for a liquid reward. Forty-five percent (34/75) of the medullary dorsal horn neurons studied exhibited task-related activity that was significantly correlated with the stereotypical behavioral events that occurred during the tasks. Similar events occurring outside of the task produced no response. In addition to the task-related activity of these medullary dorsal horn neurons, responses to mechanical and/or thermal stimuli presented within the neuron's receptive field were demonstrated in 28 of 34 cases. These sensory responses also were evoked by the same stimuli presented outside of the behavioral task. Fifteen of the neurons with task-related responses could be activated antidromically from thalamic stimulating electrodes. Task-related responses were categorized according to their relationship to the three phases of the behavioral trial: trial initiation, trial continuation, and trial termination. Although an individual task-related response was associated with a single behavioral event, most medullary dorsal horn neurons (30/34) exhibited a reproducible pattern of task-related responses that occurred during more than one phase of the trial. Trial-initiation task-related responses were subdivided depending on their correlation with specific events that occurred within that phase of the trial. One-third of the 18 excitatory trial-initiation responses were associated with the visual stimulus that cued the monkey to begin the trial; the remaining two-thirds were associated with the monkey's press of the button that actually initiated the trial. Trial-continuation task-related responses (observed while the monkey waited for a thermal stimulus that triggered a rewarded motor response) were shown to be independent of the actual temperature of the thermal stimulus. In addition these trial-continuation task-related responses were also noted during trials without a thermal stimulus, in which the trigger cue was the onset of a light (in a visual task).(ABSTRACT TRUNCATED AT 400 WORDS)

Structure-function relationships in rat medullary and cervical dorsal horns. II. Medullary dorsal horn cells.

In Nembutal-anesthetized rats, 31 physiologically identified medullary dorsal horn (MDH) cells were labeled with horseradish peroxidase (HRP). Ten responded only to deflection of one or more vibrissae. Six cells were activated by guard hair movement only, six by deflection of guard hairs or vibrissa(e), and seven by pinch of facial skin with serrated forceps. Different classes of low-threshold cells could not be distinguished on the basis of their somadendritic morphologies or laminar distribution. Neurons activated by multiple vibrissae were unique, however, in that one sent its axon into the medial lemniscus, and three projected into the trigeminal spinal tract. None of the guard hair-only or vibrissae-plus-guard hair neurons had such projections. Cells that responded best to noxious stimulation were located mainly in laminae I, II, and deep V, while neurons activated by vibrissa(e) and/or guard hair deflection were located in layers III, IV, and superficial V. Low-threshold neurons generally had fairly thick dendrites with few spines, whereas high-threshold cells tended to have thinner dendrites with numerous spines. Moreover, the dendritic arbors of low-threshold cells were, for the most part, denser than those of the noxious cells. Neurons with mandibular receptive fields were located in the dorsomedial portion of the MDH; cells with ophthalmic fields were found in the ventrolateral MDH, and maxillary cells were interposed. Cells sensitive to deflection of dorsal mystacial vibrissae and/or guard hairs were located ventral to those activated by more ventral hairs. Neurons with rostral receptive fields were found in the rostral MDH, while cells activated by hairs of the caudal mystacial pad, periauricular, and periorbital regions were located in the caudal MDH. Receptive-field types were encountered that have not been reported for trigeminal primary afferent neurons: multiple vibrissae; vibrissae plus guard hairs; and wide dynamic range. The latter two can be explained by the convergence of different primary afferent types onto individual neurons. Our failure to find a significant relationship between dendritic area (in the transverse plane) and the number of vibrissae suggests that primary afferent convergence may not be responsible for the synthesis of the multiple vibrissae receptive field. Excitatory connections between MDH neurons may, therefore, account for multiple vibrissae receptive fields in the MDH.

Strychnine and l-allylglycine but not bicuculline and picrotoxin induce transsynaptic degeneration following transection of the inferior alveolar nerve in adult rats

The effects of the convulsants strychnine, bicuculline, picrotoxin and l-allylglycine on the transsynaptic destruction of medullary dorsal horn neurons were examined following transection of the inferior alveolar nerve in adult rats. Strychnine and l-allylglycine enhanced the transsynaptic effect of nerve transection and caused degeneration of many dorsal horn neurons, while bicuculline and picrotoxin did not. The removal of glycinergic and GABAergic postsynaptic inhibition appears to enhance the transsynaptic destructive activity which follows the peripheral nerve transection.

Stomatology Activity of trigeminothalamic neurons in medullary dorsal horn of awake monkeys trained in a thermal discrimination task: J. Neurophysiol., 52 (1984) 170–187

Stomatology Activity of trigeminothalamic neurons in medullary dorsal horn of awake monkeys trained in a thermal discrimination task: J. Neurophysiol., 52 (1984) 170–187

Activity of trigeminothalamic neurons in medullary dorsal horn of awake monkeys trained in a thermal discrimination task.

We analyzed the activity of 51 trigeminothalamic neurons in the medullary dorsal horn (trigeminal nucleus caudalis) of monkeys during the performance of behavioral tasks requiring the monkeys to discriminate innocuous and noxious thermal stimuli applied to the face and to detect the onset of visual stimuli. Static properties of trigeminothalamic neurons in behaving monkeys were similar to those in anesthetized monkeys. Responses to passively presented mechanical and thermal stimuli, receptive-field properties, and conduction velocities did not differ in the awake and anesthetized states. For most wide dynamic range and nociceptive-specific trigeminothalamic neurons, there was a negative correlation between the magnitude of thermally evoked activity and behavioral latencies to discriminate 47 and 49 degrees C stimuli. Thus, both groups of neurons provide information that could be used by the monkey to discriminate noxious thermal stimuli. The magnitude of thermal responses of trigeminothalamic neurons was modulated by the behavioral significance of the stimulus. Behaviorally relevant thermal stimuli presented during the thermal discrimination task produced a greater neuronal response than equivalent irrelevant thermal stimuli presented between behavioral trials or presented while the monkey performed the visual detection task. Neurons whose activity is modulated by behavioral state are likely to be involved in discrimination of thermal stimuli, since the activity of these neurons correlates with the behavioral response to the stimuli and information from the modulated neurons is sent to the thalamus. Some trigeminothalamic neurons that exhibited somatosensory responses also responded to behaviorally relevant stimuli and events associated with trial initiation and receipt of reward in the behavioral tasks. Similar events outside a behavioral task evoked no neuronal responses. These task-related responses were similar to those described previously for medullary dorsal horn neurons not identified as to projection sites (14).(ABSTRACT TRUNCATED AT 400 WORDS)

An electrophysiological study of canine, premolar and molar tooth pulp afferents and their convergence on medullary trigeminal neurons

The two main aims of this study were (1) to compare the conduction velocities of tooth pulp (TP) afferents innervating the cat canine, premolar and molar teeth and (2) to determine the degree of convergence of afferent input originating in these different teeth on medullary dorsal horn (MDH) neurons. Experiments were con- ducted on 10 cats anesthetized with chloralose. Single unit extracellular recordings were obtained from the tooth pulp or the MDH. The distribution of conduction velocities of afferents originating in the mandibular and maxillary canines, premolars and mandibular molar were all found to be similar except that the mean conduction velocity of canine afferents was slightly higher than the means for the other teeth. A total of 48 MDH neurons excited by TP stimulation was studied. Most MDH neurons activated by electrical stimulation of one of the TPs could also be activated by stimulation of one or more of the other TPs. In addition to the marked convergence from different teeth, most of the TP-activated neurons also had convergent inputs from facial skin and/or intraoral mucosa.

Pharmacological differentiation between responses of rat medullary dorsal horn neurons to noxious mechanical and noxious thermal cutaneous stimuli

Responses of lamina V medullary dorsal horn neurons to noxious thermal and noxious mechanical facial stimuli were challenged with iontophoretically applied cis-2,3-piperidine dicarboxlic acid, a broad spectrum excitatory amino acid antagonist. This antagonist reduced neuronal responses to noxious mechanical stimuli but not responses to noxious thermal stimuli. These results suggest that different neural mechanisms underlie the responses of lamina V neurons to different noxious stimuli, and that responses to noxious mechanical stimuli appear to involve excitatory amino acid receptors.

An anatomical demonstration of projections to the medullary dorsal horn (trigeminal nucleus caudalis) from rostral trigeminal nuclei and the contralateral caudal medulla

This study demonstrates that the medullary dorsal horn (MDH), the most caudal subdivision of the spinal trigeminal nucleus, receives input from neurons located in the trigeminal main sensory nucleus, the more rostral subdivisions of the spinal trigeminal nucleus, and the contralateral MDH. Using the retrograde transport of horseradish peroxidase (HRP), we show here that the MDH receives ipsilateral projections from rostral trigeminal nuclei but not from adjacent areas of the reticular formation. The rostral pole of spinal trigeminal nucleus oralis (nucleus oralis, pars β) contains the highest density of MDH projection neurons. In addition, the MDH on one side receives projections from contralateral MDH neurons located in layers I, III, IV, V, VII and VIII but not from neurons in layers II and VI. We conclude that: (1) specific subdivisions of rostral trigeminal nuclei send projections to the MDH that could modulate the activity of MDH neurons; (2) projections from trigeminal nuclei to layers V and VI of the MDH, but not from adjacent areas of the reticular formation, provide further evidence that these deeper layers are related functionally to the MDH and trigeminal sensory processes; and (3) several populations of MDH neurons send axons across the midline into the contralateral MDH and may mediate contralateral inhibitory effects.

Postsynaptic inhibition of cat medullary dorsal horn neurons by stimulation of nucleus raphe magnus and other brain stem sites

Sensory responses of neurons in the medullary and spinal cord dorsal horn can be inhibited by stimulation of a number of brain stem regions. These regions include the nucleus raphe magnus (NRM), the nucleus reticularis gigantocellularis (NGC), the nucleus reticularis magnocellularis (NMC), the periaqueductal gray (PAG), and the nucleus cuneiformis (CU). The purpose of this study was to determine whether or not this inhibition is mediated by postsynaptic processes. Experiments were carried out on chloralose-anesthetized cats. The responses of 29 medullary dorsal horn (trigeminal subnucleus caudalis) cells were recorded with carbon-fiber microelectrodes. Included were cells which responded to noxious stimulation (nine cells) as well as cells which responded only to nonnoxious input. The presence of postsynaptic inhibition was tested by two indirect techniques. We studied the effects of conditioning stimulation of the five regions on the latency of antidromically activated cells and also on the firing rate of neurons excited by iontophoretically applied glutamate. Conditioning stimulation was associated with a block or increased latency of antidromic activation in 15 of 18 nociceptive and nonnociceptive neurons. These effects reflect membrane hyperpolarization, presumably resulting from postsynaptic inhibition. Furthermore, conditioning stimulation of these regions inhibited the glutamate-evoked firing of all 11 cells tested, also indicating a postsynaptic type of inhibition of medullary dorsal horn cells. Thus these results indicate that at least part of the inhibition induced by stimulation of the NRM, NGC, NMC, PAG, and the CU probably results from postsynaptic inhibitory mechanisms.

Functional properties of neurons in cat trigeminal subnucleus caudalis (medullary dorsal horn). II. Modulation of responses to noxious and nonnoxious stimuli by periaqueductal gray, nucleus raphe magnus, cerebral cortex, and afferent influences, and effect of naloxone.

Functional properties of neurons in cat trigeminal subnucleus caudalis (medullary dorsal horn). II. Modulation of responses to noxious and nonnoxious stimuli by periaqueductal gray, nucleus raphe magnus, cerebral cortex, and afferent influences, and effect of naloxone.

Functional properties of neurons in cat trigeminal subnucleus caudalis (medullary dorsal horn). I. Responses to oral-facial noxious and nonnoxious stimuli and projections to thalamus and subnucleus oralis.

Functional properties of neurons in cat trigeminal subnucleus caudalis (medullary dorsal horn). I. Responses to oral-facial noxious and nonnoxious stimuli and projections to thalamus and subnucleus oralis.

Sensitivity of cutaneous cold fibers to noxious heat: paradoxical cold discharge

ArticlesSensitivity of cutaneous cold fibers to noxious heat: paradoxical cold dischargeR. R. LongR. R. LongPublished Online:01 May 1977https://doi.org/10.1152/jn.1977.40.3.489MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited BySpike propagation through the dorsal root ganglia in an unmyelinated sensory neuron: a modeling studyDanielle Sundt, Nikita Gamper, and David B. Jaffe11 December 2015 | Journal of Neurophysiology, Vol. 114, No. 6Responses of intact and injured sural nerve fibers to cooling and mentholAlina Teliban, Fabian Bartsch, Marek Struck, Ralf Baron, and Wilfrid Jänig15 May 2014 | Journal of Neurophysiology, Vol. 111, No. 10Dry eye modifies the thermal and menthol responses in rat corneal primary afferent cool cellsMasayuki Kurose, and Ian D. Meng15 July 2013 | Journal of Neurophysiology, Vol. 110, No. 2Ocular dryness excites two classes of corneal afferent neurons implicated in basal tearing in rats: involvement of transient receptor potential channelsHarumitsu Hirata, and Michael L. Oshinsky15 February 2012 | Journal of Neurophysiology, Vol. 107, No. 4Temperature perception and nociception1 January 2004 | Journal of Neurobiology, Vol. 61, No. 1Identification and function of thermosensory neurons in Drosophila larvae3 February 2003 | Nature Neuroscience, Vol. 6, No. 3A cold- and menthol-activated current in rat dorsal root ganglion neurones: properties and role in cold transduction22 July 2004 | The Journal of Physiology, Vol. 545, No. 2Clinical and electrophysiologic correlates of quantitative sensory testing in patients with incomplete spinal cord injuryArchives of Physical Medicine and Rehabilitation, Vol. 83, No. 11Slowly conducting afferents activated by innocuous low temperature in human skin5 August 2004 | The Journal of Physiology, Vol. 535, No. 3Physiological Properties of the Lamina I Spinoparabrachial Neurons in the RatHervé Bester, Victoria Chapman, Jean-Marie Besson, and Jean-François Bernard1 April 2000 | Journal of Neurophysiology, Vol. 83, No. 4Quantitative Analysis of Orofacial Thermoreceptive Neurons in the Superficial Medullary Dorsal Horn of the RatW. D. Hutchison, J. Tsoukatos, and J. O. Dostrovsky1 June 1997 | Journal of Neurophysiology, Vol. 77, No. 6Segmental release of Met-enkephalin-like material from the spinal cord of rats, elicited by noxious thermal stimuliBrain Research, Vol. 484, No. 1-2Response to an itch-producing substance in cat. II. Cutaneous receptor populations with unmyelinated axonsBrain Research, Vol. 413, No. 1Painful sensation induced by a thermal cutaneous stimulusPain, Vol. 17, No. 2Psychophysical detection and pain ratings of incremental thermal stimuli: A comparison with nociceptor responses in humansBrain Research, Vol. 274, No. 1Unmyelinated nociceptive units in two skin areas of the ratBrain Research, Vol. 267, No. 1Response properties of high-threshold cutaneous cold receptors in the primateBrain Research, Vol. 244, No. 2 More from this issue > Volume 40Issue 3May 1977Pages 489-502 Copyright & PermissionsCopyright © 1977 the American Physiological Societyhttps://doi.org/10.1152/jn.1977.40.3.489PubMed406366History Published online 1 May 1977 Published in print 1 May 1977 Metrics

Neural processes in thermoregulation.

Neural processes in thermoregulation.

Hyperpolarizing influence of trigeminal nucleus caudalis on primary afferent preterminals in trigeminal nucleus oralis.

Hyperpolarizing influence of trigeminal nucleus caudalis on primary afferent preterminals in trigeminal nucleus oralis.C J Scibetta, and R B KingC J Scibetta, and R B KingPublished Online:01 Mar 1969https://doi.org/10.1152/jn.1969.32.2.229MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByCornea-Responsive Medullary Dorsal Horn Neurons: Modulation by Local Opioids and Projections to Thalamus and Brain StemHarumitsu Hirata, Shinichiro Takeshita, James W. Hu, and David A. Bereiter1 August 2000 | Journal of Neurophysiology, Vol. 84, No. 2Differential Effects of Morphine on Corneal-Responsive Neurons in Rostral Versus Caudal Regions of Spinal Trigeminal Nucleus in the RatIan D. Meng, James W. Hu, and David A. Bereiter1 May 1998 | Journal of Neurophysiology, Vol. 79, No. 5Encoding of Corneal Input in Two Distinct Regions of the Spinal Trigeminal Nucleus in the Rat: Cutaneous Receptive Field Properties, Responses to Thermal and Chemical Stimulation, Modulation by Diffuse Noxious Inhibitory Controls, and Projections to the Parabrachial AreaI. D. Meng, J. W. Hu, A. P. Benetti, and D. A. Bereiter1 January 1997 | Journal of Neurophysiology, Vol. 77, No. 1Golgi and immunocytochemical analysis of neurons in trigeminal subnucleus interpolaris: Correlations with cellular localization of enkephalinNeuroscience, Vol. 32, No. 2The rostral part of the trigeminal sensory complex is involved in orofacial nociceptionBrain Research, Vol. 448, No. 1Lesions of the Mid-Spinal trigeminal complex are effective in producing perioral thermal hypoalgesiaBrain Research, Vol. 382, No. 2Effects of trigeminal tractotomy on facial thermal nociception in the ratBrain Research, Vol. 333, No. 1Peripheral and central substrates involved in the Rostrad transmission of nociceptive informationPain, Vol. 13, No. 1Presynaptic excitability changes produced in brain stem endings of tooth pulp afferents by raphe and other central and peripheral influencesBrain Research, Vol. 218, No. 1-2Peripheral and central pathways in painPharmacology & Therapeutics, Vol. 14, No. 3Odorant responses in taste neurons of the rat NTSBrain Research, Vol. 135, No. 2Responses in the rostral medulla to electrical stimulation of an intranasal trigeminal nerve: Convergence of oral and nasal inputsNeuroscience Letters, Vol. 5, No. 6Response patterns to noxious and non-noxious stimuli in rostral trigeminal relay nucleiBrain Research, Vol. 97, No. 1Jamming spinal sensory input: Effects of anesthetic and analgesic drugs in the spinal cord dorsal hornPain, Vol. 1, No. 3Differences in the excitability of two populations of trigeminal primary afferent central terminalsBrain Research, Vol. 77, No. 2Trigeminal main sensory nucleus polymodal unit responses to noxious and non-noxious stimuliBrain Research, Vol. 72, No. 1Fine structural aspects of the synaptic organization of spinal trigeminal nucleus (pars interpolaris) of the catBrain Research, Vol. 25, No. 2Presynaptic inhibition of jaw-opening reflex by high threshold afferents from the masseter muscle of the catBrain Research, Vol. 23, No. 2Presynaptic hyperpolarization of fibers projecting to trigeminal brain stem and thalamic nucleiBrain Research, Vol. 22, No. 1 More from this issue > Volume 32Issue 2March 1969Pages 229-38 https://doi.org/10.1152/jn.1969.32.2.229PubMed4304624History Published online 1 March 1969 Published in print 1 March 1969 Metrics

Four aspects of trigeminal nucleus and a paradox.

Four aspects of trigeminal nucleus and a paradox.