Trigeminal Nuclear Complex Research Articles

5-HT-Immunoreactive fibers in the trigeminal nuclear complex of the rat.

The distribution of serotonin immunoreactive (5-HT-IR) fibers in the trigeminal nuclear complex of the rat was mapped. In the sensory nuclei, innervation appeared to be dense in areas primarily related to nociceptive afferent activity, and sparse in areas primarily related to nonnociceptive afferent activity. Specifically, the marginal and gelatinosa layers of the spinal subnucleus caudalis contained many 5-HT-IR fibers while few labeled fibers were seen in the magnocellular portion of subnucleus caudalis or in the principal sensory nucleus. The spinal subnuclei oralis and interpolaris were sparsely innervated except for a few areas which contained more 5-HT-IR fibers. The motor nucleus contained as many immunoreactive fibers as the subnucleus caudalis, although fibers in the motor nucleus were thicker and varicosities more irregularly spaced than in caudalis.

Three-dimensional stereotactic anatomy of the human trigeminal nerve nuclear complex.

The trigeminal nuclear complex and its spinal tract extend throughout the greater part of the brain-stem and at medullary levels form the target site for producing stereotactic lesions. This paper describes a method for three-dimensional drawings of this nuclear complex. A stereotactic atlas of the human brain-stem and cerebellar nuclei has formed the data base. The two-dimensional composite transverse sections, at 1-mm intervals have been digitized using an X-Y coordinate plotting microscope. Computer programs have been written to generate drawings of a single transverse hemisection as well as regeneration of the opposite hemibrain-stem section. Specific programs were used to reconstruct serial transverse section outlines and incorporate the trigeminal nuclear complex with and without hidden line removal techniques and colour graphic display facilities. Rotation about the x, y and z axes was possible and permits any view of the reconstructed specimen to be computer-generated. A further program for reconstructing structures as stereopairs is presented.

Trigeminal primary afferents project bilaterally to dorsal horn and ipsilaterally to cerebellum, reticular formation, and cuneate, solitary, supratrigeminal and vagal nuclei

Horseradish peroxidase (HRP) applied to the transected mandibular division of the trigeminal ganglion was transported anterogradely to previously well known primary afferent terminal zones in the dorsal brainstem trigeminal nuclear complex of the rat, and retrogradely to cell bodies in the trigeminal motor, supratrigeminal and mesencephalic nuclei. Primary trigeminal afferents were also visible in the ipsilateral cerebellar cortex and paraflocculus, and the dentate, cuneate, solitary, supratrigeminal, and dorsal motor vagal nuclei, parvicellular reticular formation, area postrema, and C1–C6 dorsal horn. The contralateral medulla and cervical dorsal horn were also innervated by primary afferents which crossed in the posterior commissure. These projections were also labeled when HRP was applied to individual sensory branches of the mandibular nerve.

Rostral trigeminal projections signal perioral facial pain

Sagittal knife cuts were made interrupting efferent projections of either the rostral or the caudal trigeminal nuclear complex in the rat. Only rostral cuts resulted in significant, specific deficits in ipsilateral facial nociception. These results are not consistent with a well-known view which emphasizes only caudal nuclear projections as critical for orofacial pain.

Cerebellar afferents to paramedian lobule from the trigeminal complex in Tupaia glis: a horseradish peroxidase (HRP) study.

Projections from the trigeminal complex to paramedian lobule (PML) were studied in the tree shrew (Tupaia glis) by means of retrograde transport of horseradish peroxidase (HRP). Neurons which project to both dorsal and ventral folia of PML are located primarily in those areas of the trigeminal nuclear complex interpreted as nucleus interpolaris (Vi) and caudal areas of the nucleus oralis (Vo). The majority of HRP-labeled neurons lie in ventral and ventrolateral regions of Vi/Vo. No HRP-reactive cells are present in the principal (Vp), mesencephalic, or motor nuclei nor in nucleus caudalis or rostral portions of oralis. The majority of trigeminocerebellar (TC) cells are found in ipsilateral Vi; however, sparse numbers of labeled somata are present in this subnucleus on the contralateral side. Within Vi/Vo, small fusiform and medium-and large-sized multipolar neurons contain HRP-reaction product. Large multipolar cells are found primarily in ventrolateral portions of Vi/Vo, while medium and small neurons are scattered throughout the ventral half of the nucleus. Small-sized neurons are also present dorsally within Vi/Vo. Axons of labeled TC cells course laterally through the spinal trigeminal tract, enter medial aspects of the restiform body, and arch dorsally into the cerebellum.

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.

Somatotopic representation of eye muscle proprioception within the superior colliculus of the lamb

A somatotopic organization of the extraocular muscle proprioceptive afferent projection was observed in the superior colliculus of the lamb. Units responding to the stretching of each extraocular muscle were recorded along the dorsoventral axis in the superficial layers of the superior colliculus as follows: the inferior rectus and the inferior oblique were represented in the most dorsal layer of the superior colliculus, the superior rectus, and the superior oblique muscles in the intermediate layers, and the lateral and the medial recti in the deepest layers. The superior collicular sites influenced by stretching the extrinsic eye muscles could be activated by single-shock electrical stimulation of the cellular pool of the dorsal part of the semilunar ganglion and by stimulation of both the nucleus principalis and the pars oralis of the trigeminal nuclear complex ipsilaterally, where the eye muscle proprioception is represented. Our findings indicate for the first time that in the superior colliculus a somatotopic map of extraocular afferent input is present; the significance of this projection is discussed in relation to the control of head movements and extraocular proprioception.

Negative potentials evoked by nucleus reticularis gigantocellularis in the spinal trigeminal tract of the cat

In cats that were precollicularly decerebrated, bilateral elactrical stimulation of the nucleus reticularis gigantocellularis (NRGC) evoked negative potentials in the spinal trigeminal tract at the level of the subnucleus oralis of the spinal trigeminal nuclear complex. These negative potentials exhibited two types of configurations that differed in the slope of the rising and declining phase, duration, and amplitude of the negative wave. They were also found to develop as a function of the reticular stimulus parameters. Thus, they possessed electrophysiologic characteristics similar to the dorsal root potentials induced by comparable reticular activation in the spinal cord. The time course of the NRGC-evoked negative potential paralleled the inhibition of dental pulp-elicited responses in the subnucleus oralis, promoted by the same reticular stimulation. As the dorsal root potential is generally taken to be a manifestation of primary afferent depolarization, it is suggested, by extrapolation, that the NRGC may, at least in part, suppress the transmission of nociceptive signals from the dental pulp by a depolarization of the pulpal afferent fibers.

Neurotensin-containing cell bodies, fibers and nerve terminals in the brain stem of the rat: Immunohistochemical mapping

Neurotensin immunoreactive perikarya, fibers and nerve terminals, visualized by the indirect immunohistofluorescent method in colchicine-pretreated animals, are localized in many discrete regions of the rat brain stem. Cell body groups are found in the inner aspect of the substantia gelatinosa of the caudal trigeminal nuclear complex, the nucleus of the solitary tract, the parabrachial nuclei, the locus coeruleus, the dorsal raphénucleus, the periaqueductal gray matter, and the ventral tegmental area of Tsai. These areas of cell body density are accompanied by concentrations of fibers and terminals, while the occasional positive perikaryon noted in the dorsal cochlear nucleus is accompanied by only sparse fluorescent fiber/terminal patterns. Other brain stem regions, such as the floor of the fourth ventricle and aspects of the caudal ventrolateral reticular formation, possess substantial numbers of fibers and terminals that are not accompanied by cell bodies. Many aspects of this distribution coincide with the brain stem distribution of the enkephalin pentapeptides, though significant differences in localization are also evident. Interactions of neurotensin with other neurotransmitter candidates are also suggested by its presence in areas enriched in norepinephrine, dopamine, serotonin, and substance P. Certain neurotensin localizations suggest an association of the peptide with functional brain systems preferentially involving these regions. In particular periaqueductal gray and substantia gelatinosa neurotensin synapses are plausible sites for the analgesia elicited after intercisternal injection of low doses of neurotensin.

Immunohistochemical mapping of enkephalin containing cell bodies, fibers and nerve terminals in the brain stem of the rat

Enkephalin immunoreactive perikarya, fibers and nerve terminals, visualized by the indirect immunohistofluorescent method in colchicine-pretreated animals, are localized in many discrete regions of the rat brain stem. These specific immunohistofluorescent patterns are similar after staining with selective primary antisera directed against either methione-enkephalin or leucine-enkephalin. Cell bodies are found in the substantia gelatinosa and interpolaris zones of the trigeminal nuclear complex, the nucleus of the solitary tract, in the vicinity of the nucleus raphe´magnus, in the dorsal cochlear, medial vestibular, and paraolivary nuclei and, dorsal to this last region, in the parabrachial nuclei and the dorsal tegmental nucleus of Gudden, in the periaqueductal gray matter and interpeduncular nucleus and along the borders of the lateral lemniscus and medial geniculate. In some areas, such as the parabrachial region, nucleus of the solitary tract and substantia gelatinosa of the trigeminal nucleus, these perikarya are associated with densities of fibers and terminals. Other regions, such as the dorsal cochlear nucleus and the vicinity of the nucleus raphe´magnus, contain cell bodies associated with low densities of processes and terminals. In still other nuclei, such as the nucleus of the facial nerve and the locus coeruleus, fiber and terminal densities without associated cell bodies are evident. Many of these enkephalin localizations can be rationalized on the basis of known actions of opiate drugs and the brain stem distribution of opiate receptors.

Evidence for primary afferent depolarization of single tooth-pulp afferents in the cat.

1. Responses of single tooth-pulp afferents to electrical stimulation of sites in the trigeminal sensory nuclear complex were recorded from caine teeth in cats. 2. Changes in the excitability of the central terminals of a pulpal afferent after stimulation of other groups of sensory nerves were taken as evidence for changes in their polarization. 3. Electrical stimulation of nerves in other teeth resulted in raised excitability of the central terminals of pulpal afferents lasting up to 300 msec. The greatest effects were observed 30--100 msec after the conditioning stimulus. 4. Increased terminal excitability was also observed after the ipsilateral infraorbital nerve was stimulated. This occurred when only nerve fibres with conduction velocities in the A alpha range were excited. 5. Mechanical stimulation of a canine tooth produced increases in terminal excitability of pulpal afferents innervating the same tooth. 6. A similar effect was also observed after a brief pull on a group of ipsilateral mystacial vibrissae. 7. No evidence of decreases in the excitability of the central terminals of tooth-pulp afferents was obtained with any of the conditioning stimuli.

Bilateral and unilateral antinociceptive effects of rostral trigeminal nuclear complex lesions in rats

Behavioural responses to two different orofacial noxious stimulations were analysed following lesion of spinal trigeminal subnucleus oralis (Sp5O) in the rat. Lesions were obtained by intranuclear microinjections of quinolinic acid (0.4 μl of 60 nmol/μl solution). The control groups received microinjection of saline. Noxious stimulation was a subcutaneous injection of formalin into the upper lip or electrical stimulation of the tooth pulp. The measured behavioural responses were duration of rubbing induced by the formalin injection and thresholds of the jaw-opening reflex (JOR), head rotation (HR) and face rubbing (FR) evoked by the pulp stimulation. In addition, formalin injection was also performed in two groups of rats that had received intranuclear injection of quinolinic acid or saline into rostral subnucleus caudalis (Sp5C). Rubbing duration was not significantly modified by the lesion of Sp5O, whereas a significant decrease occurred after the lesion of rostral Sp5C. After the lesion of Sp5O, an increase in the threshold of JOR was observed whereas the thresholds of HR and FR were not significantly modified. These results suggest that Sp5O is not necessary for the processing and relay of nociceptive inputs triggered by intense stimulations of oral and perioral areas. However further experiments are needed to reconcile these results with the relevant data obtained from cell recording experiments which indicate the existence, in Sp5O, of neuronal activities related to the sensory discriminative aspect of intense nociception.

Afferents to the cerebellar lateral nucleus. Evidence from retrograde transport of horseradish peroxidase after pressure injections through micropipettes.

HRP was injected by pressure from glass capillary micropipettes unilaterally into the lateral nucleus of rat so as to encompass the entire nucleus, but without spread into the interpositus nuclei. The cells of origin of the afferents to the lateral nucleus were studied after retrograde transport of the HRP. The reticulotegmental nucleus of the pons was labelled bilaterally and is the major source of crossed and uncrossed reticular imputs. The pontine nuclei also provide extensive crossed and uncrossed afferents. The inferior olive gives a large crossed olivo-lateral nucleus projection and a minor uncrossed input. The trigeminal nuclear complex--the nucleus of the spinal tract and the mesencephalic, principal sensory, and motor nuclei--all provide uncrossed afferents. The rostral portion of the lateral reticular nucleus gives a small crossed and uncrossed projection while the perihypoglossal nuclei and the dorsal parabrachial body give crossed afferents to the lateral nucleus. The norepinephrine afferent system from the locus coeruleus is represented by one or two heavily labelled cells and the serotonin raphe systems come from at least five raphe subgroups, the dorsal, superior centralis, pontis, obscurus and magnus nuclei. No evidence was found for commissural fibers between ipsilateral or contralateral cerebellar nuclei, or afferent axons from the spinocerebellar nuclei and the paramedian retricular nucleus. The significance of these sources of afferent imputs to the lateral cerebellar nucleus is discussed. The question is raised of the direct relationship between size of terminal axonal arborization and the quantity of HRP granules present in a cell retrograde transport. The limitations of the HRP method for detecting subtle local differences in the distribution of afferents within the heterogeneous groups of neurons in the lateral nucleus are discussed.

The ascending fiber projections from the mandibular subdivision in the trigeminal nuclear complex of the rat

Many studies on the ascending pathways from the trigeminal sensory nuclear complex were reported, but a few reports dealt with the fiber projections from the subnuclear subdivisions of trigeminal sensory nuclear complex systematically were found.The purpose of the present experiment is to clarify the ascending pathways from the mandibular subdivision in the trigeminal sensory nuclear complex of the rat by using the Fink-Heimer and Marchi methods. The trigeminal sensory nuclear complex was divided into the main sensory nucleus and the nucleus of the trigeminal spinal tract (subnucleus oralis, interporalis and caudalis).The experimental lesions were produced to the mandibular division which was confirmed by the previous studies.Degenerated fibers emanated from the main sensory nucleus terminated in the contralateral thalamus via only the crossed ventral trigeminothalamic tract. The ventral tract crossed at the midline dorsal to the interpeduncular nucleus and ascended along the medial lemniscus. At the level of the superior colliculus, a few degenerated fibers terminated in the medial geniculate complex pars medialis (PO). The rest ascended rostrally and terminated in the ventral part of the zona inzerta (ZI). At this level, however, terminal degeneration in the caudal third of the ventrobasal thalamic complex pars medialis (VPM) was small amount. From the middle third of VPM heavy degeneration was produced and ended to the medial part of it. In addition, heavy terminal degeneration could be traced in the most rostral and ventromedial part of it.Degenerated fibers ascending to the thalamus from the subnucleus oralis were very small amount, and very sparse terminal degeneration were found at the caudal and middle part of VPM. On the other hand, both PO and ZI were free from terminal endings.Degenerated fibers from the subnucleus interporalis crossed immediately and ascended along the medial lemniscus to PO, ZI and VPM. Terminal degeneration was found in the all rostrocaudal level of VPM, but not found in the most medial part of VPM. Terminal endings in VPM were more dense than thost of the subnucleus oralis.Following the lesion restricted to the subnucleus caudalis, a small amount of degeneration was noticed in the contralateral PO, but not in ZI. In VPM, terminal degeneration was found in caudal two thirds of it. No degeneration could be found in the rostral one third of VPM as seen in the sections from the main sensory nucleus and the subnucleus interporalis.Judging from above-mentioned results, the thalamic afferent fibers originated from the mandibular division of trigeminal sensory nuclear complex could be found by way of the only crossed ventral tract, but the dorsal trigemino-thalamic tract and homolateral pathways could not be found. Theterminal endings from the different sites of the lesion produced some.differences in the density and terminal areas in the thalamus.In the rat, it appears that the impulses from the mandibular division to the thalamus are directly conducted only by crossed trigemino-thalmic ventral tract. But, the route to the ipsilateral thalmic neurons from the trigeminal sensory nuclear complex is thought to be multisynaptic via the reticular formation etc.

Projections of the subnucleus caudalis of the trigeminal nucleus in the sheep.

AbstractA study has been made of the efferent connections of the trigeminal sibnucleus caudalis in 12 shep. Lesions were placed in this nucleus either surgically or by means of an electrical cautery device. Resulting degeneration was determined by staining serially prepared frozen sections according to the silver techniques of Nauta and Fink‐Heimer. Ipsilateral connections are desribed with the fifth, seventh eleventh and twelfth cranial nerve motor nuclei, and ascending ipsilateral connections with all of the more rostral portions of the trigeminal nuclear complex. Evidence of widespread bilateral trigemino‐reticular connections is reported. By contrast, only a small number of fibers from the subnucleus caudalis were found to ascend in the mdial lemniscus; few of these lemniscal fibers appear to ascend beyond mesencephalic levels.

Fine structural aspects of the synaptic organization of spinal trigeminal nucleus (pars interpolaris) of the cat

Pars interpolaris of the spinal trigeminal nuclear complex has been studied electron microscopically in normal adult cats and after total ipsilateral retrogasserian rhizotomy. Small cell body profiles are numerous and have few axo-somatic synapses. Larger cell body profiles are few in number but have several axo-somatic synapses. Axo-dendritic synaptic contacts are numerous and axo-axonic serial synapses are seen at all levels. Presynaptic profiles containing predominantly round vesicles are usually characterized by an asymmetrical postynaptic specialization and those with many flattened vesicles usually have a symmetrical specialization. A small proportion of profiles with flattened vesicles are associated with an asymmetrical specialization. Axo-axonic synapses have flattened vesicle profiles presynaptic to round vesicle ones. Degeneration of axons and presynaptic processes are seen at 30 h survival and become rare after 7 days. Most degenerated processes are electron-dense and associated with an asymmetrical specialization. In serial synapses the round vesicle profile degenerates. After 3 days many degenerated endings are replaced by glial and other processes which are applied to the denervated postsynaptic specialization. After 7 days survival some unaltered flattened vesicle profiles appear to migrate into the denervated postsynaptic sites. Later survivals show such endings applied to both symmetrical and asymmetrical specializations on the same dendritic profile. Other origins for unaltered presynaptic processes are considered. A correlation between denervated postsynaptic sites and neuronal hyperactivity is discussed, as is the apparent synaptic reorganization or re-innervation of these denervated sites.

Central eye nystagmus in the pontomesencephalic preparation

An acute “pontomesencephalic” preparation, surgically separated from the thalamus and from the medulla oblongata, was prepared in the guinea pig. A region was isolated from the other parts of the central nervous system by two transections, one rostral to the oculomotor nuclei and the other just caudal to the abducent nuclei. This preparation was also deprived of the cerebellum and of all the vestibular nuclear complex; it contained only the nuclei of cranial nerves III, IV, and VI, part of the trigeminal nuclear complex and part of the reticular formation. Electrical stimulation of the surface of one superior colliculus still produced contraversive quick-phase ocular nystagmus. This ponto mesencephalic preparation represented the minimal brain-stem portion indispensable for central eye nystagmus. We concluded that the neural mechanism for central ocular nystagmus is located in the brain stem between and including the oculomotor and abducent nuclei. While the reticular formation seemed to be involved in the circuitry of central eye nystagmus, the vestibular nuclei were not essential.

Projections of the anterior ectosylvian gyrus to the thalamus, the dorsal column nuclei, the trigeminal nuclei and the spinal cord in cats

1. Descending projections of the anterior ectosylvian gyrus (AEct) were studied with the Nauta-Gygax method of secondary degeneration on the basis of total and partial cortical removals in 11 cats. 2. Thalamus. Degenerated fibers were traced to the posterior ventral, lateral ventral, reticular, anterior ventral, centralis lateralis, centre me´dian and the so-called posterior group nuclei. A somatotopic organization was found with respect to the projection into the posterior VP nuclei: anterior part of AEct to dorsolateral VPM (except for the most lateral region), middle part of AEct to medial division of VPL and the most lateral portions of VPM, posterior part of AEct to the lateral division of VPL. No somatotopic arrangement was found with respect to connections to other thalamic nuclei including the PO group. 3. Pons and medulla oblongata. Degenerated fibers were found in the trigeminal nuclear complex and adjacent lateral reticular formation (anterior AEct), in the cuneate nucleus (middle AEct) and in the gracile nucleus (posterior AEct). The trigeminal projections were found mainly in the principal sensory nucleus and in the ‘c’ subnucleus of the oral division of the spinal trigeminal complex. 4. Spinal cord. Degenerated fibers were found mainly in the cervical cord, and few at the thoracic and lumbar levels. They were traced to the basal layers of the contralateral dorsal horn. Very few fibers seem to end in the more dorsal layers of the dorsal horn or in the intermediate zone. No degenerated fibers were found ipsilaterally.

Somatotopic organization of mechanoreceptor units in the trigeminal nuclear complex of the macaque

AbstractThe properties of neurons in the sensory trigeminal nuclear complex of macaque monkeys have been investigated by a systematic exploration of the principal sub‐divisions in an attempt to define somatotopic organization, modality representation, receptive field size and adaptive properties. Particular attention was paid to several discrepancies in the literature on the cat trigeminal complex. The results suggest that each cutaneous locus is represented by a rostro‐caudally oriented column of neurons possessing comparable properties and receptive field sizes at all levels examined in deeply anesthetized animals. A consistent somatotopic pattern with minor variations, was evident at all rostro‐caudal levels. Criteria for distinguishing “spinothalmic” and “lemniscal” neuron properties in appropriate portions of the sensory complex (inferred from human data) could not be identified. Neurons in adjacent structures may respond to crude stimuli and lack distinct receptive fields, but it is unlikely that these are related to an afferent “pain” pathway.

Organization of somatic afferents to the diencephalon.

THREE main areas within the diencephalon are known to be concerned with somatosensory mechanisms; these are the ventrobasal complex, the intralaminar complex, and the posterior group. It is generally accepted that the afferents to the ventrobasal complex are organized in a simple somatotopic fashion1,2, whereas the input to the intralaminar complex3,4 and to the posterior group4,5 is non-somatotopic and generally of long latency. The arrangement of afferents to the ventrobasal complex may be more complex than previously supposed6,7, and the lateral thalamic nuclei may also be involved in somatosensory activity7. Furthermore, the properties of the nuclei of the dorsal column show a rostro-caudal differentiation8,9, and it has been suggested that this is reflected in a differential termination of the medial lemniscus10. We have investigated the distribution of degeneration in the rat diencephalon using the Nauta method11,12 after lesions made separately in the gracile and cuneate nuclei, the spinal cord at different levels from the spinomedullary junction to the lumbar region, and the trigeminal nuclear complex.