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Michael Ariel - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE Injections of Algesic Solutions into Muscle Activate the Lateral Reticular Formation: A Nociceptive Relay of the Spinoreticulothalamic Tract
2016Co-Authors: Michael W Panneton, Qi Gan, Michael ArielAbstract:Although musculoskeletal pain disorders are common clinically, the central processing of muscle pain is little understood. The present study reports on central neurons activated by injections of algesic solutions into the gastrocnemius muscle of the rat, and their subse-quent localization by c-Fos immunohistochemistry in the spinal cord and brainstem. An injection (300μl) of an algesic solution (6 % hypertonic saline, pH 4.0 acetate buffer, or 0.05 % capsaicin) was made into the gastrocnemius muscle and the distribution of immuno-labeled neurons compared to that obtained after control injections of phosphate buffered saline [pH 7.0]. Most labeled neurons in the spinal cord were found in laminae IV-V, VI, VII and X, comparing favorably with other studies, with fewer labeled neurons in laminae I and II. This finding is consistent with the diffuse pain perception due to noxious stimuli to mus-cles mediated by sensory fibers to deep spinal neurons as compared to more restricted pain localization during noxious stimuli to skin mediated by sensory fibers to superficial lam-inae. Numerous neurons were immunolabeled in the brainstem, predominantly in the Lateral Reticular Formation (LRF). Labeled neurons were found biLaterally in the caudalmost ventro
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injections of algesic solutions into muscle activate the Lateral Reticular Formation a nociceptive relay of the spinoreticulothalamic tract
PLOS ONE, 2015Co-Authors: Michael W Panneton, Michael ArielAbstract:Although musculoskeletal pain disorders are common clinically, the central processing of muscle pain is little understood. The present study reports on central neurons activated by injections of algesic solutions into the gastrocnemius muscle of the rat, and their subsequent localization by c-Fos immunohistochemistry in the spinal cord and brainstem. An injection (300μl) of an algesic solution (6% hypertonic saline, pH 4.0 acetate buffer, or 0.05% capsaicin) was made into the gastrocnemius muscle and the distribution of immunolabeled neurons compared to that obtained after control injections of phosphate buffered saline [pH 7.0]. Most labeled neurons in the spinal cord were found in laminae IV-V, VI, VII and X, comparing favorably with other studies, with fewer labeled neurons in laminae I and II. This finding is consistent with the diffuse pain perception due to noxious stimuli to muscles mediated by sensory fibers to deep spinal neurons as compared to more restricted pain localization during noxious stimuli to skin mediated by sensory fibers to superficial laminae. Numerous neurons were immunolabeled in the brainstem, predominantly in the Lateral Reticular Formation (LRF). Labeled neurons were found biLaterally in the caudalmost ventroLateral medulla, where neurons responsive to noxious stimulation of cutaneous and visceral structures lie. Immunolabeled neurons in the LRF continued rostrally and dorsally along the intermediate Reticular nucleus in the medulla, including the subnucleus Reticularis dorsalis caudally and the parvicellular Reticular nucleus more rostrally, and through the pons medial and Lateral to the motor trigeminal nucleus, including the subcoerulear network. Immunolabeled neurons, many of them catecholaminergic, were found biLaterally in the nucleus tractus solitarii, the gracile nucleus, the A1 area, the CVLM and RVLM, the superior salivatory nucleus, the nucleus locus coeruleus, the A5 area, and the nucleus raphe magnus in the pons. The external Lateral and superior Lateral subnuclei of the parabrachial nuclear complex were consistently labeled in experimental data, but they also were labeled in many control cases. The internal Lateral subnucleus of the parabrachial complex was labeled moderately. Few immunolabeled neurons were found in the medial Reticular Formation, however, but the rostroventromedial medulla was labeled consistently. These data are discussed in terms of an interoceptive, multisynaptic spinoreticulothalamic path, with its large receptive fields and role in the motivational-affective components of pain perceptions.
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Line drawings illustrating c-Fos activated neurons after a uniLateral injection of an algesic solution into the right GCM.
2015Co-Authors: Michael W Panneton, Qi Gan, Michael ArielAbstract:Symbols represent a single labeled neuron after injections of buffered normal saline (blue circles), capsaicin (yellow diamonds), low pH acetate buffer (green triangles), and 6% hypertonic saline (red squares). Note the preponderance of immunolabeled neurons in the Lateral Reticular Formation after injections of these algesics into muscle. Also note that immunoreactive neurons in the spinal trigeminal nucleus, parvocellular Lateral Reticular nucleus and pontine nuclei are not drawn. Numbers to the right of figures represent mm ± 120μm from interaural zero. Abbreviations found on figures: 10.1371/journal.pone.0130939.t001A1 - noradrenergic cell group of caudal medulla A5 - noradrenergic cell group in ventroLateral pons Amb - nucleus ambiguus AP - area postrema cmVLM - caudalmost ventroLateral medulla Cu - cuneate nucleus ECu - external cuneate nucleus GiA - gigantocellular Reticular nucleus, pars alpha Gr - gracile nucleus IO - inferior olivary nucleus LC - nucleus locus coeruleus Li - linear nucleus of medulla LRF - Lateral Reticular Formation of brainstem LRt - Lateral Reticular nucleus MDH - medullary dorsal horn Me5 - nucleus of the mesencephalic tract of the trigeminal nerve Mo5 - motor trigeminal nucleus MRF - medial Reticular Formation MVe - medial vestibular nucleus PBil - parabrachial nucleus, internal Lateral subnucleus Pr5 - principal trigeminal nucleus Pn - pontine nuclei RMg - raphe magnus nucleus RVLM - pressor area of the rostral medulla Sol, NTS - nucleus tractus solitarii SO - superior olivary nucleus Sp5I - nucleus of the spinal tract of the trigeminal nerve, interpolar part Sp5O - nucleus of the spinal tract of the trigeminal nerve, oral part SRD - subnucleus Reticularis dorsalis SVe - spinal vestibular nucleus Tz - trapezoid nucleus VC - ventral cochlear nucleus VLL - ventral nucleus of Lateral leminiscus VMM - ventromedial medulla bc - brachium conjunctivum g7 - genu of facial nerve mcp - middle cerebellar peduncle m5 - motor root of 5n n7 - facial nerve py - pyramidal tract sol - tractus solitarii sp5 - spinal tract of the trigeminal nerve 7 - facial motor nucleus 7n - facial nerve root 12 - hypoglossal motor nucleus
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Micrographs of sections through the rostral medulla (between 3.18–3.42 mm caudal to interaural zero) after a uniLateral injection of an algesic solution into the right GCM.
2015Co-Authors: Michael W Panneton, Qi Gan, Michael ArielAbstract:Each column is headed by a photomontage (A, D, G) of a complete section of a case after injection of capsaicin (A-C), low pH (D-F), or 6% saline (G-I). Similar to the caudal medulla, labeled neurons extended from the ventroLateral medulla through the Lateral Reticular Formation (outlined in A, D, G; arrows in E, H). Other immunoreactive profiles were found in the rostroventroLateral medulla (B, E), but only some were double labeled with tyrosine hydroxylase (B, red arrow). Numerous labeled profiles also were labeled in the ventromedial medulla (C, F; red arrows). However, very few labeled neurons were found in the medial Reticular Formation in the medulla (C, F, I). Black boxes in A, D, and G represent areas magnified in B, E, and H; white boxes represent areas magnified in C, F, and I.
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Micrographs of sections through the caudal medulla (between 5.18–5.42 mm caudal to interaural zero) after a uniLateral injection of an algesic solution into the right GCM.
2015Co-Authors: Michael W Panneton, Qi Gan, Michael ArielAbstract:Each column is headed by a photomontage (A, D, G) of a complete section of a case after injection of capsaicin (A-C), low pH (D-F), or 6% saline (G-I). Many reactive neurons were found in the Lateral Reticular Formation from the caudalmost ventroLateral medulla angling dorsomedially towards the nucleus tractus solitarii (A, D, G; outlined), adjacent to the contours of the intermediate Reticular nucleus. Such labeled neurons thus were found in the caudalmost ventroLateral medulla (B, C, F), dorsal medullary Reticular Formation (labeled LRF; B, C, F, H), and subnucleus Reticularis dorsalis (E, H), forming a diffuse band of neurons activated by these different algesic solutions. The larger profiles just dorsal to the Lateral Reticular nucleus (B, C, F) often were double-labeled with antibodies against tyrosine hydroxylase (F) and thus are labeled the A1 group of catecholamine neurons. Black boxes in A, D, and G represent areas magnified in B, E, and H; white boxes represent areas magnified in C, F, and I.
Michael W Panneton - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE Injections of Algesic Solutions into Muscle Activate the Lateral Reticular Formation: A Nociceptive Relay of the Spinoreticulothalamic Tract
2016Co-Authors: Michael W Panneton, Qi Gan, Michael ArielAbstract:Although musculoskeletal pain disorders are common clinically, the central processing of muscle pain is little understood. The present study reports on central neurons activated by injections of algesic solutions into the gastrocnemius muscle of the rat, and their subse-quent localization by c-Fos immunohistochemistry in the spinal cord and brainstem. An injection (300μl) of an algesic solution (6 % hypertonic saline, pH 4.0 acetate buffer, or 0.05 % capsaicin) was made into the gastrocnemius muscle and the distribution of immuno-labeled neurons compared to that obtained after control injections of phosphate buffered saline [pH 7.0]. Most labeled neurons in the spinal cord were found in laminae IV-V, VI, VII and X, comparing favorably with other studies, with fewer labeled neurons in laminae I and II. This finding is consistent with the diffuse pain perception due to noxious stimuli to mus-cles mediated by sensory fibers to deep spinal neurons as compared to more restricted pain localization during noxious stimuli to skin mediated by sensory fibers to superficial lam-inae. Numerous neurons were immunolabeled in the brainstem, predominantly in the Lateral Reticular Formation (LRF). Labeled neurons were found biLaterally in the caudalmost ventro
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injections of algesic solutions into muscle activate the Lateral Reticular Formation a nociceptive relay of the spinoreticulothalamic tract
PLOS ONE, 2015Co-Authors: Michael W Panneton, Michael ArielAbstract:Although musculoskeletal pain disorders are common clinically, the central processing of muscle pain is little understood. The present study reports on central neurons activated by injections of algesic solutions into the gastrocnemius muscle of the rat, and their subsequent localization by c-Fos immunohistochemistry in the spinal cord and brainstem. An injection (300μl) of an algesic solution (6% hypertonic saline, pH 4.0 acetate buffer, or 0.05% capsaicin) was made into the gastrocnemius muscle and the distribution of immunolabeled neurons compared to that obtained after control injections of phosphate buffered saline [pH 7.0]. Most labeled neurons in the spinal cord were found in laminae IV-V, VI, VII and X, comparing favorably with other studies, with fewer labeled neurons in laminae I and II. This finding is consistent with the diffuse pain perception due to noxious stimuli to muscles mediated by sensory fibers to deep spinal neurons as compared to more restricted pain localization during noxious stimuli to skin mediated by sensory fibers to superficial laminae. Numerous neurons were immunolabeled in the brainstem, predominantly in the Lateral Reticular Formation (LRF). Labeled neurons were found biLaterally in the caudalmost ventroLateral medulla, where neurons responsive to noxious stimulation of cutaneous and visceral structures lie. Immunolabeled neurons in the LRF continued rostrally and dorsally along the intermediate Reticular nucleus in the medulla, including the subnucleus Reticularis dorsalis caudally and the parvicellular Reticular nucleus more rostrally, and through the pons medial and Lateral to the motor trigeminal nucleus, including the subcoerulear network. Immunolabeled neurons, many of them catecholaminergic, were found biLaterally in the nucleus tractus solitarii, the gracile nucleus, the A1 area, the CVLM and RVLM, the superior salivatory nucleus, the nucleus locus coeruleus, the A5 area, and the nucleus raphe magnus in the pons. The external Lateral and superior Lateral subnuclei of the parabrachial nuclear complex were consistently labeled in experimental data, but they also were labeled in many control cases. The internal Lateral subnucleus of the parabrachial complex was labeled moderately. Few immunolabeled neurons were found in the medial Reticular Formation, however, but the rostroventromedial medulla was labeled consistently. These data are discussed in terms of an interoceptive, multisynaptic spinoreticulothalamic path, with its large receptive fields and role in the motivational-affective components of pain perceptions.
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Line drawings illustrating c-Fos activated neurons after a uniLateral injection of an algesic solution into the right GCM.
2015Co-Authors: Michael W Panneton, Qi Gan, Michael ArielAbstract:Symbols represent a single labeled neuron after injections of buffered normal saline (blue circles), capsaicin (yellow diamonds), low pH acetate buffer (green triangles), and 6% hypertonic saline (red squares). Note the preponderance of immunolabeled neurons in the Lateral Reticular Formation after injections of these algesics into muscle. Also note that immunoreactive neurons in the spinal trigeminal nucleus, parvocellular Lateral Reticular nucleus and pontine nuclei are not drawn. Numbers to the right of figures represent mm ± 120μm from interaural zero. Abbreviations found on figures: 10.1371/journal.pone.0130939.t001A1 - noradrenergic cell group of caudal medulla A5 - noradrenergic cell group in ventroLateral pons Amb - nucleus ambiguus AP - area postrema cmVLM - caudalmost ventroLateral medulla Cu - cuneate nucleus ECu - external cuneate nucleus GiA - gigantocellular Reticular nucleus, pars alpha Gr - gracile nucleus IO - inferior olivary nucleus LC - nucleus locus coeruleus Li - linear nucleus of medulla LRF - Lateral Reticular Formation of brainstem LRt - Lateral Reticular nucleus MDH - medullary dorsal horn Me5 - nucleus of the mesencephalic tract of the trigeminal nerve Mo5 - motor trigeminal nucleus MRF - medial Reticular Formation MVe - medial vestibular nucleus PBil - parabrachial nucleus, internal Lateral subnucleus Pr5 - principal trigeminal nucleus Pn - pontine nuclei RMg - raphe magnus nucleus RVLM - pressor area of the rostral medulla Sol, NTS - nucleus tractus solitarii SO - superior olivary nucleus Sp5I - nucleus of the spinal tract of the trigeminal nerve, interpolar part Sp5O - nucleus of the spinal tract of the trigeminal nerve, oral part SRD - subnucleus Reticularis dorsalis SVe - spinal vestibular nucleus Tz - trapezoid nucleus VC - ventral cochlear nucleus VLL - ventral nucleus of Lateral leminiscus VMM - ventromedial medulla bc - brachium conjunctivum g7 - genu of facial nerve mcp - middle cerebellar peduncle m5 - motor root of 5n n7 - facial nerve py - pyramidal tract sol - tractus solitarii sp5 - spinal tract of the trigeminal nerve 7 - facial motor nucleus 7n - facial nerve root 12 - hypoglossal motor nucleus
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Micrographs of sections through the rostral medulla (between 3.18–3.42 mm caudal to interaural zero) after a uniLateral injection of an algesic solution into the right GCM.
2015Co-Authors: Michael W Panneton, Qi Gan, Michael ArielAbstract:Each column is headed by a photomontage (A, D, G) of a complete section of a case after injection of capsaicin (A-C), low pH (D-F), or 6% saline (G-I). Similar to the caudal medulla, labeled neurons extended from the ventroLateral medulla through the Lateral Reticular Formation (outlined in A, D, G; arrows in E, H). Other immunoreactive profiles were found in the rostroventroLateral medulla (B, E), but only some were double labeled with tyrosine hydroxylase (B, red arrow). Numerous labeled profiles also were labeled in the ventromedial medulla (C, F; red arrows). However, very few labeled neurons were found in the medial Reticular Formation in the medulla (C, F, I). Black boxes in A, D, and G represent areas magnified in B, E, and H; white boxes represent areas magnified in C, F, and I.
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Micrographs of sections through the caudal medulla (between 5.18–5.42 mm caudal to interaural zero) after a uniLateral injection of an algesic solution into the right GCM.
2015Co-Authors: Michael W Panneton, Qi Gan, Michael ArielAbstract:Each column is headed by a photomontage (A, D, G) of a complete section of a case after injection of capsaicin (A-C), low pH (D-F), or 6% saline (G-I). Many reactive neurons were found in the Lateral Reticular Formation from the caudalmost ventroLateral medulla angling dorsomedially towards the nucleus tractus solitarii (A, D, G; outlined), adjacent to the contours of the intermediate Reticular nucleus. Such labeled neurons thus were found in the caudalmost ventroLateral medulla (B, C, F), dorsal medullary Reticular Formation (labeled LRF; B, C, F, H), and subnucleus Reticularis dorsalis (E, H), forming a diffuse band of neurons activated by these different algesic solutions. The larger profiles just dorsal to the Lateral Reticular nucleus (B, C, F) often were double-labeled with antibodies against tyrosine hydroxylase (F) and thus are labeled the A1 group of catecholamine neurons. Black boxes in A, D, and G represent areas magnified in B, E, and H; white boxes represent areas magnified in C, F, and I.
Masahiko Takada - One of the best experts on this subject based on the ideXlab platform.
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Input-output organization of jaw movement-related areas in monkey frontal cortex.
The Journal of comparative neurology, 2005Co-Authors: Nobuhiko Hatanaka, Hironobu Tokuno, Atsushi Nambu, Tomio Inoue, Masahiko TakadaAbstract:The brain mechanisms underlying mastication are not fully understood. To address this issue, we analyzed the distribution patterns of cortico–striatal and cortico–brainstem axon terminals and the origin of thalamocortical and intracortical fibers by injecting anterograde/retrograde tracers into physiologically and morphologically defined jaw movement-related cortical areas. Four areas were identified in the macaque monkey: the primary and supplementary orofacial motor areas (MIoro and SMAoro) and the principal and deep parts of the cortical masticatory area (CMaAp and CMaAd), where intracortical microstimulation produced single twitch-like or rhythmic jaw movements, respectively. Tracer injections into these areas labeled terminals in the ipsiLateral putamen in a topographic fashion (MIoro vs. SMAoro and CMaAp vs. CMaAd), in the Lateral Reticular Formation and trigeminal sensory nuclei contraLaterally (MIoro and CMaAp) or biLaterally (SMAoro) in a complex manner of segregation vs. overlap, and in the medial parabranchial and Kolliker-Fuse nuclei contraLaterally (CMaAd). The MIoro and CMaAp received thalamic projections from the ventroLateral and ventroposteroLateral nuclei, the SMAoro from the ventroanterior and ventroLateral nuclei, and the CMaAd from the ventroposteromedial nucleus. The MIoro, SMAoro, CMaAp, and CMaAd received intracortical projections from the ventral premotor cortex and primary somatosensory cortex, the ventral premotor cortex and rostral cingulate motor area, the ventral premotor cortex and area 7b, and various sensory areas. In addition, the MIoro and CMaAp received projections from the three other jaw movement-related areas. Our results suggest that the four jaw movement-related cortical areas may play important roles in the Formation of distinctive masticatory patterns. J. Comp. Neurol. 492:401–425, 2005. © 2005 Wiley-Liss, Inc.
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distribution of gabaergic and glycinergic premotor neurons projecting to the facial and hypoglossal nuclei in the rat
The Journal of Comparative Neurology, 1997Co-Authors: Masahiko Takada, Takeshi Kaneko, Noboru MizunoAbstract:The distribution of inhibitory premotor neurons for the facial and hypoglossal nuclei was examined in the lower brainstem of the rat. A retrograde axonal tracing method with the fluorescent tracer, tetramethylrhodamine dextran amine (TMR-DA), was combined with immunofluorescence histochemistry for glutamic acid decarboxylase (GAD), i.e., the enzyme involved in gamma-aminobutyric acid synthesis, or glycine. In the rats injected with TMR-DA uniLaterally into the facial or hypoglossal nucleus, the distribution of TMR-DA-labeled neurons showing GAD-like immunoreactivity (GAD/TMR-DA neurons) was essentially the same as that of TMR-DA-labeled neurons displaying glycine-like immunoreactivity (Gly/TMR-DA neurons). The distributions of GAD/TMR-DA and Gly/TMR-DA neurons in the rats injected with TMR-DA into the facial nucleus were also similar to those in the rats injected with TMR-DA into the hypoglossal nucleus. These neurons were seen most frequently in the Lateral aspect of the pontine Reticular Formation, the supratrigeminal region, the dorsal aspect of the Lateral Reticular Formation of the medulla oblongata, and the Reticular regions around the raphe magnus nucleus and the gigantocellular Reticular nucleus pars alpha, biLaterally with a slight dominance on the side ipsiLateral to the injection site. A number of GAD/TMR-DA and Gly/TMR-DA neurons were also seen in the oral and interpolar subnuclei of the spinal trigeminal nucleus, biLaterally with a slight ipsiLateral dominance. In the rats injected with TMR-DA into the facial nucleus, GAD/TMR-DA and Gly/TMR-DA neurons were also encountered in the paralemniscal zone of the midbrain tegmentum biLaterally with an apparent dominance on the side contraLateral to the injection site. A large part of these inhibitory premotor neurons for the facial and hypoglossal nuclei and the excitatory ones may constitute premotor neuron pools common to the orofacial motor nuclei implicated in the control of integrated orofacial movements. J. Comp. Neurol. 378:283–294, 1997. © 1997 Wiley-Liss, Inc.
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gabaergic and glycinergic neurons projecting to the trigeminal motor nucleus a double labeling study in the rat
The Journal of Comparative Neurology, 1996Co-Authors: Masahiko Takada, Takeshi KanekoAbstract:The distribution of GABAergic and glycinergic premotor neurons projecting to the trigeminal motor nucleus (Vm) was examined in the lower brainstem of the rat by a double labeling method combining retrograde axonal tracing with immunofluorescence histochemistry. After injection of the fluorescent retrograde tracer, tetramethylrhodamine dextran amine (TRDA), into the Vm uniLaterally, neurons labeled with TRDA were seen ipsiLaterally in the mesencephalic trigeminal nucleus, and biLaterally in the parabrachial region, the supratrigeminal and intertrigeminal regions, the Reticular Formation just medial to the Vm, the principal sensory and spinal trigeminal nuclei, the pontine and medullary Reticular Formation, especially the parvicellular part of the medullary Reticular Formation, the alpha part of the gigantocellular Reticular nucleus, and the medullary raphe nuclei. Some of these neurons labeled with TRDA were found to display glutamic acid decarboxylase (the enzyme involved in GABA synthesis)-like or glycine-like immunoreactivity. Such double-labeled neurons were seen mainly in the supratrigeminal region, the Reticular region adjacent to the medial border of the Vm, and the dorsal part of the Lateral Reticular Formation of the medulla oblongata; a number of them were further scattered in the intertrigeminal region, the alpha part of the gigantocellular Reticular nucleus, the nucleus raphe magnus, the principal sensory trigeminal nucleus, and the interpolar subnucleus of the spinal trigeminal nucleus. These neurons were considered to be inhibitory (GABAergic or glycinergic) neurons sending their axons to motoneurons in the Vm, or to local interneurons within and around the Vm.
Réjean Dubuc - One of the best experts on this subject based on the ideXlab platform.
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an anatomical study of brainstem projections to the trigeminal motor nucleus of lampreys
Neuroscience, 1999Co-Authors: H Huard, Réjean Dubuc, J P Lund, D VeilleuxAbstract:This study was undertaken to identify and describe populations of brainstem neurons that project to the area of the nucleus motorius nervi trigemini in lampreys as a first step in the study of neurons that control feeding behavior in this species. To identify these neurons, the retrograde tracer cobalt-lysine was injected into the nucleus motorius nervi trigemini on one side of the in vitro isolated brainstem preparation of seven spawning adult lampreys (Petromyzon marinus). Transport times ranged from 42 to 48 h. Retrogradely labeled neurons were found within the rostral spinal cord, the rhombencephalon, the mesencephalon and the caudal diencephalon. This study concentrates on the labeled neurons in the rhombencephalon, since the essential circuits for mastication and swallowing are confined to this region in higher vertebrates. Within the rhombencephalon, labeled cells were in the nucleus sensibilis nervi trigemini on both sides. A densely packed column of labeled neurons was found medial to the nucleus motorius nervi trigemini on the ipsiLateral side, extending further rostrally in the isthmic region. Continuous columns of labeled cells were observed in the Lateral Reticular Formation on each side in the basal plate ventral to rhombencephalic cranial motor nuclei. They extended from the rostral trigeminal region down into the rostral spinal cord. A comparison with data from cats and rats shows that the distribution of neurons that project to the nucleus motorius nervi trigemini is very similar in mammals and in agnathes. We conclude that the organization of the motor command network of the trigeminal system is well preserved throughout phylogeny and that the in vitro isolated brainstem of lampreys should be a useful model for the study of vertebrate feeding behavior.
Toshikatsu Yokota - One of the best experts on this subject based on the ideXlab platform.
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corneal representation within the trigeminal subnucleus caudalis and adjacent bulbar Lateral Reticular Formation of the cat
Japanese Journal of Physiology, 1991Co-Authors: Yasuhiro Nishida, Toshikatsu YokotaAbstract:Corneal units in the trigeminal subnucleus caudalis and adjacent bulbar Lateral Reticular Formation were studied in urethane-chloralose anesthetized cats. Corneal units were categorized into four classes: low-threshold corneal (LTC) units, high-threshold corneal (HTC) units, wide dynamic range (WDR) units with corneal input, and subnucleus Reticularis ventralis (SRV) units with corneal input. Corneal receptive fields of these four classes of corneal afferent units consisted of 3-6 spots. Mechanical thresholds of LTC units were lower than 30 mg (2.6 g/mm2) and were comparable to the sensory threshold of the human cornea measured in patients with cataract. Mechanical thresholds of the other 3 classes of corneal afferent units were well above the pain threshold in the human cornea. LTC units were located in the magnocellular layer of trigeminal subnucleus caudalis and were intermingled with cutaneous low-threshold mechanoreceptive units. HTC units were coexistent with nociceptive specific units in the marginal layer and in the outer zone of substantia gelatinosa. WDR units with corneal input were found in the Lateral part of trigeminal lamina V equivalent, which corresponds to the Lateral part of subnucleus Reticularis dorsalis. These 3 classes of corneal units were found at a level 2.7-3.5 mm caudal to the obex. SRV units were found in the dorsoLateral part of SRV along the entire length of the medulla oblongata caudal to the obex. These results support the suggestion that either nonpainful sensation or pain can be evoked from the cornea.
