A cervical primary afferent input to vestibular nuclei as demonstrated by retrograde transport of wheat germ agglutinin-horseradish peroxidase in the rat

Summary Wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) was microiontophoretically injected into the vestibular nuclear complex of the rat. Retrogradely labeled neurons were found in ipsilateral spinal ganglia C₂-C₃ only if the injection site was in the caudal part of the medial vestibular nucleus (MVN). Injections into rostral parts of the MVN, the superior, lateral and descending vestibular nuclei (SVN, LVN, DVN), the nucleus of the solitary tract (STN) and the reticular formation did not result in spinal ganglion labeling. Thus, the caudal part of the MVN appears to be the main vestibular termination site for rostral cervical primary afferents.Abbreviations Cu cuneate nucleus - DVN descending vestibular nucleus - ECN external cuneate nucleus - g7 genu of the facial nerve - icp inferior cerebellar peduncle - In intercalated nucleus - LVN lateral vestibular nucleus - mlf medial longitudinal fasciculus - MVN medial vestibular nucleus - PrH prepositus hypoglossi nucleus - Ro Roller's nucleus - sol solitary tract - SVN superior vestibular nucleus - 12 hypoglossal nucleus     

Cerebellar nuclear afferents from feline hypothalamus demonstrated by retrograde transport after implantation of crystalline wheat germ agglutinin-horseradish peroxidase complex

A hypothalamo-cerebellar projection has recently been discovered in the cat, and its presence has been verified in other mammalian species. Due to methodological limitations only hypothalamic projections to cerebellar cortex had been demonstrated. By means of modification of the new implantation technique described by Mori et al. [10], hypothalamic projections to the cerebellar nuclei have been revealed using retrograde transport of a wheat germ agglutinin-horseradish peroxidase complex (WGA-HRP). This method permits identification of afferents to restricted nuclear regions without uptake of the tracer into passing fibers. The projection from hypothalamus has an ipsilateral predominance and has its main terminal area in the fastigial nucleus. These findings were verified in anterograde transport experiments after hypothalamic injections of WGA-HRP.     

Cerebellar corticovestibular projections from lobule IX to the descending vestibular nucleus in the cat. A retrograde wheat germ agglutinin-horseradish peroxidase study

The distribution of Purkinje cells projecting to the descending vestibular nucleus was studied in lobule IX (uvula) of the cat by the retrograde wheat germ agglutinin-horseradish peroxidase method. In the transverse plane labeled Purkinje cells were seen diffusely within 1.0 mm from the midline and densely for 250-500 microns at around 1.0 mm lateral to the midline. Reconstruction of the distribution in the horizontal plane revealed that they were distributed in longitudinal areas extending in the apicobasal extent of lobule IX.     

Different wheat germ agglutinin-horseradish peroxidase labeling in structures related to the development of amygdaline kindling in the rat

The anterior commissure, medial and lateral bed nuclei of the stria terminalis and both sides of the medial prefrontal cortex showed a progressive increasing of wheat germ agglutinin-horseradish peroxidase labeling (WGA-HRP) in successive stages of amygdaline kindling, after 48 h of a right amygdala WGA-HRP injection. In contrast, during the first stages the number of labeled cells in the contralateral amygdala was reduced, reaching control values after the first generalized seizure. The present paper indicates that these structures are involved in the propagation and generalization of the epileptic activity. Our findings show that both sides of the medial prefrontal cortex can be activated before the contralateral amygdaloid complex, during the development of the amygdaline electrical kindling in the rat.     

Afferent projections to the cerebellar flocculus in the pigmented rat demonstrated by retrograde transport of horseradish peroxidase

The horseradish peroxidase (HRP) retrograde transport method was used to identify brainstem afferents to the cerebellar flocculus in the pigmented rat. Injections of the enzyme were made through recording microelectrodes, making it possible to localize the injection site by physiological criteria. Clearly, the largest number of afferents arise from the bilateral vestibular and perihypoglossal nuclei and from the contralateral dorsal cap (of Kooy) of the inferior olive. Additionally, a substantial number arise bilaterally from: (1) the nucleus reticularis tegmenti pontis (NRTP); (2) several of the cranial motor nuclei including the abducens, retrofacial and facial nuclei and the nucleus ambiguus; (3) the rostral part of the lateral reticular nucleus (subtrigeminal nucleus); (4) the raphe pontis and raphe magnus and (5) neurons intercalated among the medial longitudinal fasciculus (MLF) just rostral to the hypoglossal nucleus and another group rostral to the abducens nucleus. The basilar pontine nuclei contained a large number of lightly labeled neurons in all flocculus injections which were discretely located within the dorsolateral, lateral and medial divisions. These areas were labeled bilaterally but with a slight contralateral preponderance. Injection into the flocculus, but involving the adjacent ventral paraflocculus, produced a heavier labeling of pontine neurons with a slightly different distribution. Therefore, we tentatively conclude that the flocculus receives input from these pontine visual centers (dorsolateral, lateral and medial nuclei), perhaps through collateral projections from neurons projecting to the paraflocculus. The present study demonstrates strong similarities between the rat and other species studied (e.g., rabbit, cat, monkey) in terms of the brainstem nuclei projecting to the flocculus. Most noticeable in quantitative terms are the pathways known to mediate vestibular (vestibular and perihypoglossal nuclei) and visual (optokinetic) information (e.g., NRTP). Additionally, we can provide morphological evidence that the midline and paramedian pontine tegmentum, identified in the cat and monkey as containing saccade-related neurons, send large numbers of projections to the rat flocculus. Given these similarities, the rat may be a suitable animal model in which to study the pathways underlying visual-vestibular interaction and saccadic mechanisms in the flocculus.     

Selective retrograde transneuronal transport of wheat germ agglutinin-conjugated horseradish peroxidase in the oculomotor system

Summary Responses of striate cortical neurones to bars of optimal orientation and width, moving with fixed velocity, were recorded in the lightly anaesthetized cat. Effects of periods of pre-adaptation with square-wave gratings of variable spatial frequency and velocity, drifting continuously in each cell's preferred or null directions, were investigated. Variations of cells' directional bias and responsiveness to oriented bars were assessed in relation to the degree and time-course of pre-adaptation to drifting gratings, compared with the preceding level of firing when exposed to uniform backgrounds of the same average luminance. All cells showed some susceptibility to pre-adapting moving gratings: subsequent responses to a bar were initially depressed in the direction of pre-adaptation and, in direction-biased or bidirectional cells, were enhanced in the opposite direction, compared with bar responses following exposure merely to a uniform background. These effects were strongest and most consistent amongst standard complex cells and weakest amongst special complex cells: maximal effects were obtained with adapting gratings of optimal velocity and spatial frequency.     

Cerebellar afferent projections from the vestibular nuclei in the cat: An experimental study with the method of retrograde axonal transport of horseradish peroxidase

Summary Details of cerebellar afferent projections from the vestibular nuclei were investigated by the method of retrograde axonal transport of horseradish peroxidase (HRP) in the cat. The distribution of labeled cells in the vestibular nuclei following HRP injections in various parts of the cerebellum indicates that vestibular neurons in the medial and descending nuclei and cell groups f and x project bilaterally to the entire cerebellar vermis, the flocculus, the fastigial nucleus and the anterior and posterior interpositus nuclei. In addition, labeled cells (giant, medium and small) were consistently found bilaterally in the superior and lateral vestibular nuclei following HRP injections in the nodulus, flocculus, fastigial nucleus, and following large injections in the vermis. No labeled cells were observed in cases of HRP injections in crus I and II, the paramedian lobule, paraflocculus and lateral cerebellar nuclei. The present findings indicate that secondary vestibulocerebellar fibers project to larger areas in the cerebellum and originate from more subdivisions and cell groups of the vestibular nuclear complex than previously known.List of Abbreviations B.c. superior cerebellar peduncle (brachium conjunctivum) - D descending (inferior) vestibular nucleus - f cell group f in descending vestibular nucleus - g group rich in glia cells, caudal to the medial vestibular nucleus - HIX hemispheral lobule IX - HVIIA cr. Ia, p; cr. IIa, p anterior and posterior folia of crus I and II of the ansiform lobule - HVIIB, HVIIIA, B sublobules A and B of hemispheral lobules VII and VIII - i.c. nucleus intercalatus (Staderini) - L lateral vestibular nucleus (Deiters) - l small-celled lateral group of lateral vestibular nucleus - M medial (triangular or dorsal) vestibular nucleus - N. cu. e. accessory cuneate nucleus - N. f. c. cuneate nucleus - N. mes. V mesencephalic nucleus of trigeminal nerve - N.tr. s. nucleus of solitary tract - N. VII facial nerve - pfl. d. dorsal paraflocculus - pfl. v. ventral paraflocculus - S superior vestibular nucleus (Bechterew) - Sv. cell group probably representing the nucleus supravestibularis - Tr. s. solitary tract - x small-celled group x, lateral to the descending vestibular nucleus - y small-celled groupy, lateral to the lateral vestibular nucleus (Deiters) - z cell group dorsal to the caudal part of the descending vestibular nucleus - I–VI vermian lobules I–VI - V, VI, XII cranial motor nerve nuclei - VIIA, B; VIIIA, B anterior and posterior sublobules of lobules VII and VIII - IX uvula - X nodulus; dorsal motor nucleus of vagus nerve On leave from the Laboratory of Neurobiology and Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand, under the Felllowship Program of the Norwegian Agency for International Development (NORAD)     

The central cervical nucleus — A source of spinocerebellar fibres,demonstrated by retrograde transport of horseradish peroxidase

Injections of horseradish peroxidase in the cerebellum of kittens resulted in labelling of cells in the central cervical nucleus (CCN) in the upper cervical spinal cord. The largest number of labelled CCN neurones was found after injections including the anterior part of the anterior lobe of the cerebellum. In this neuronal system horseradish peroxidase was transported at a maximal velocity of about 150 mm/day.     

A direct projection from the medial vestibular nucleus to the cervical spinal dorsal horn of the rat, as demonstrated by anterograde and retrograde tracing

Summary Phaseolus vulgaris leucoagglutinin and wheat germ agglutinin-horseradish peroxidase were iontophoretically injected into different parts of the vestibular nuclear complex (VNC) of the rat. Injections centered into the caudal part of the medial vestibular nucleus revealed a vestibulospinal projection predominantly to the dorsal horn of the cervical spinal cord, besides the expected projection to the intermediate zone (IZ) and ventral horn (VH). While most of the anterogradely labelled fibres could be localized in laminae III to V, some scattered fibres were also seen in laminae I and VI. Lamina II remained free of labelling. The dorsal horn (DH) area with detectable anterograde labelling showed a rostrocaudal extension from C₁-C₆. Injections into other parts of the VNC labelled fibres and terminals in the IZ and VH while the DH remained almost free of labelling. Additionally, fluorogold and wheat germ agglutininhorseradish peroxidase were pressure- or iontophoretically injected at different levels into the spinal cord to confirm the projection to the dorsal horn by means of retrograde tracing. Labelled neurons in the area of the medial vestibular nucleus (MVN), from which anterograde labelling in the DH was obtained, were only detectable after fluorogold and wheat germ agglutinin-horseradish peroxidase injections into the cervical spinal cord, in particular its DH. This projection from the caudal medial vestibular nucleus to the dorsal horn of the cervical spinal cord probably enables the VNC to influence sensory processing in the DH, in addition to its well-established influence on posture and locomotion via projections to the intermediate zone and ventral horn.Abbreviations BSA bovine serum albumin - CuN cuneate nucleus - CCN central cervical nucleus - cMVN caudal medial vestibular nucleus - cVST caudal vestibulospinal tract - DAB diaminobenzidine - DH dorsal horn - DRG dorsal root ganglia - DVN descending vestibular nucleus - ECN external cuneate nucleus - FCS fetal calf serum - FG fluorogold - HRP horseradish peroxidase - icp inferior cerebellar peduncle - In intercalated nucleus - IZ intermediate zone - LVN lateral vestibular nucleus - LVST lateral vestibulospinal tract - mlf medial longitudinal fasciculus - MVN medial vestibular nucleus - MVST medial vestibulospinal tract - PHA-L Phaseolus vulgaris leucoagglutinin - PrH praepositus hypoglossi nucleus - rMVN rostral medial vestibular nucleus - Ro Roller's nucleus - SVN superior vestibular nucleus - TMB tetramethylbenzidine - VH ventral horn - VNC vestibular nuclear complex - WGAHRP wheat germ agglutinin-horseradish peroxidase - 12 hypoglossal nucleus Dedicated to Prof. J.W. Rohen on the occasion of his 70th birthday     

Afferent projections to A10 dopaminergic neurones in the rat as shown by the retrograde transport of horseradisd peroxidase

Following the microiontophoresis of horseradish peroxidase to the ventral tegmental area of Tsai, neurones labelled by retrograde transport of the enzyme were observed in a large number of sites throughout the brain. In addition to confirming previously described afferents, these studies suggest so far unknown systems projecting to the area from cerebral cortex, hypothalamus, amygdala, thalamus, superior colliculus, substantia nigra, parabrachial nuclei and medulla oblongata.     

Somatotopic termination of the spino-olivary fibers in the cat,studied with the wheat germ agglutinin-horseradish peroxidase technique

Summary Terminal sites of the spino-olivary fibers (SOFs) were examined by the anterograde transport of wheat germ agglutinin-horseradish peroxidase in the cat. The tracer was injected at various spinal cord levels from the first cervical to the caudal segments. The SOFs derived from the C1-T1 segments terminated medially in the caudal half (levels II–VIII of Brodal) of the medial accessory olive (MAO), which projects to the A zone of the cerebellar cortex, whereas the SOFs derived from the L6-S1 segments terminated laterally in the caudal half (levels I–VIII) of the MAO. No projections were found from the T2-L5 segments to the MAO. In the dorsal accessory olive (DAO), the SOFs terminated at levels III–XIV; the DAO projects to the B zone and the C1 and C3 zones of the cerebellar cortex. The SOFs derived from the C1-C4 segments terminated in the most medial part of the DAO (levels III–XIV), followed laterally by those from the C5-T1 segments. Further laterally, the SOFs derived from the T2-L5 and the L6-S1 segments terminated in the mediolateral order at levels V–XIV. The SOFs from the L6-S1 segments occupied the most lateral part of the DAO. The present study demonstrates that there is a distinct somatotopic termination of the SOFs in the mediolateral order in the caudal MAO and the DAO.     

Olivary afferents from the raphe nuclei as studied with retrograde transport of horseradish peroxidase

Summary The afferent projection to the olive from the raphe nuclei in the cat has been studied in animals where microinjections of horseradish peroxidase have been made into the inferior olive from a ventral approach. Retrogradely labelled cells were present in the three caudalmost raphe nuclei: the nucleus raphe pallidus, obscurus and magnus. The retrogradely labelled cells are of all sizes, and there appears to be a higher concentration of cells on the side ipsilateral to the injection. The observations demonstrate that all three major subdivisions of the olive — the medial accessory, the dorsal accessory and the principal olive — all receive efferent raphe fibres. No retrogradely labelled cells were present in the other raphe nuclei.The findings are discussed and related to other tracer studies dealing with olivary afferents from the raphe complex.     

Projection of thalamic neurons to cat primary vestibular cortical fields studied by means of retrograde axonal transport of horseradish peroxidase

Summary The two vestibular cortical projection areas in the anterior suprasylvian sulcus and post-cruciate dimple regions were defined by evoked potential technique in anaesthetized cats. The thalamic location of neurons with axon terminals in these fields was determined using the method of retrograde axonal transport of horseradish peroxidase. The ascending vestibular pathway appeared to be separated also at the thalamic level, where cells in the ventro-posterolateral nucleus were found to project to the post cruciate dimple and cells in the posterior nuclear group to the anterior suprasylvian vestibular cortical fields.     

Basal ganglia projections to the brain stem in the lizard Varanus exanthematicus as demonstrated by retrograde transport of horseradish peroxidase

In the present study the cells of origin of basal ganglia projections to the brain stem have been studied with the horseradish peroxidase technique in the lizard, Varanus exanthematicus. Injections of horseradish peroxidase were made at various levels of the brain stem from the mesodiencephalic border to the obex as well as in the tectum mesencephali. Efferent libers from the telencephalon to the diencephalon and the brain stem were found to arise predominantly from the striatum. From the present data it seems likely that the basal ganglia in Varanus exanthematicus as in other reptiles consist of two parts, a rostral ‘striatal’ part with projections mainly to the diencephalon and mesencephalon including the substantia nigra and a caudal ‘pallidal’ part with projections to the intercollicular nucleus and the rhombencephalic reticular formation.Injections of horseradish peroxidase into various parts of the rhombencephalic reticular formation have shown rather extensive projections from diencephalic and mesencephalic structures which receive afferents from the striatum: the posterior entopeduncular nucleus, the intercollicular nucleus and the substantia nigra were found to project as far caudal as the nucleus reticularis inferior. The substantia nigra shows, as regards its fiber connections, striking similarities to the mammalian substantia nigra, whereas the intercollicular nucleus possibly represents the reptilian homologue of the mammalian pedunculopontine nucleus.Injections of horseradish peroxidase into the tectum mesencephali have shown labeled cells in the nucleus of the posterior commissure, the posterior entopeduncular nucleus and the substantia nigra, all centers which are known to receive afferents from the striatum. Thus, the striatum can influence bisynaptically the reptilian homologue of the mammalian superior colliculus.It can be concluded that the striatum of the lizard, Varanus exanthematicus, has extensive direct as well as indirect projections to centers which influence the motor apparatus of the brain stem and spinal cord. Thus in reptiles it seems likely that the striatum exerts its influence on motor activity mainly via descending projections, in contrast to mammals where both descending and ascending striatal efferent pathways occur.     

The rubro-olivary tract in the cat, as demonstrated with the method of retrograde transport of horseradish peroxidase

The rubro-olivary projection in the cat was investigated by means of the retrograde transport of horseradish peroxidase. After injections in the inferior olive, more than a thousand labelled neurons were found in the ipsilateral red nucleus. These neurons had triangular-shaped cell bodies with an average diameter of 26.4 +/- 7.7 microns (mean +/- S.E.M.) and had few dendrites. Between 85% and 95% of the rubro-olivary neurons were found in the rostral third of the red nucleus (between A 5.5 and A 7). Morphologically, the rubro-olivary neurons are similar to rubro-thalamic neurons. Previous studies with retrograde transport of horseradish peroxidase have failed to demonstrate an extensive projection from the red nucleus to the inferior olive. These results are discussed in relation to our own findings.     

Various types of corticotectal neurons of cats as demonstrated by means of retrograde axonal transport of horseradish peroxidase

Summary The retrograde labeling of cortical neurons with horseradish peroxidase (HRP) was used to investigate the morphological features of neurons in various cortical areas projecting to the superior colliculus in the cat.Corticotectal cells were found to be labeled in layer V of the entire cerebral cortex. The number of labeled cells and their locations varied according to the sites of injections of HRP in the colliculus. Most of the Corticotectal cells identified in the present study were small (9–20 m in diameter, 66%) and medium (20–40 urn, 30%) pyramidal neurons and only 4% of them were large (more than 40 m). The labeled cells, 261 in total number, had somal diameters of 20.8±8.0 m (mean and SD). The range of sizes of the labeled neurons was different in different cortical areas. For example, the labeled neurons in the Clare-Bishop area had a greater proportion of large diameter cells than in other areas.The present findings are largely in agreement with the previous data of anterograde degeneration methods with respect to the topographical correlation of the Corticotectal projections. However, in some cortical areas, e.g., the sensorimotor and the first visual (area 17) cortex of the lateral surface of the hemisphere, relatively small numbers of Corticotectal neurons appear to have been labeled by retrogradely transported HRP. The sparsity of the labeled neurons in certain cortical areas may reflect the existence of Corticotectal neurons with axon collaterals supplying brain structures other than the superior colliculus.Abbreviations A.c. Aqueductus cerebri - AEct Gyrus ectosylvius anterior - AEs Sulcus ectosylvius anterior - AI Stratum album intermediale - AL Gyrus lateralis anterior - AP Stratum album profundum - AS Gyrus sylvius anterior - Cd Nucleus caudatus - F.l.m. Fasciculus longitudinalis medialis - GI Stratum griseum intermediale - GP Stratum griseum profundum - GS Stratum griseum superficiale - Ic Inferior colliculus - L Left - MEct Gyrus ectosylvius medius - MS Gyrus sylvius medius - MSup Gyrus suprasylvius medius - N.r. Nucleus ruber - O Stratum opticum - P Pontine nuclei - P.c. Pedunculus cerebri - PEct Gyrus ectosylvius posterior - P.g. Periaqueductal gray matter - PSigm Gyrus sigmoideus posterior - PSup Gyrus suprasylvius posterior - R Right - Sc Superior colliculus - S.n. Substantia nigra - Z Statum zonale - II Optic nerve - III and IV Motor nuclei of cranial nerves     

Basal ganglia and other afferent projections to the peribrachial region in the rat: A study using retrograde and anterograde transport of horseradish peroxidase

The afferent projections to the peribrachial region in the rat were studied using retrograde and anterograde transport of horseradish peroxidase. Particular attention was paid to descending projections from the basal ganglia and related nuclei to the region of nucleus tegmenti pedunculopontinus. Following injection of peroxidase into nucleus tegmenti pedunculopontinus, few retrogradely-labelled neurons were found in the entopeduncular nucleus proper, but larger numbers were found with a wide distribution within the boundaries of the internal capsule and cerebral peduncle. Labelled cells were also consistently observed in the amygdala, the caudal globus pallidus, the subthalamus including zona incerta and subthalamic nucleus, the hypothalamus, the substantia nigra and the ventral tegmental area. Following iontophoretic injections of horseradish peroxidase into the entopeduncular nucleus, lateral hypothalamus, subthalamic nucleus or ventral tegmental area, terminal labelling was observed in and around the branchium conjunctivum in an area apparently corresponding to nucleus tegmenti pedunculopontinus in the rat.     

Cerebellar afferent projections from the perihypoglossal nuclei: An experimental study with the method of retrograde axonal transport of horseradish peroxidase

Summary Details of cerebellar afferent projections from the perihypoglossal nuclei were studied in the cat by means of retrograde axonal transport of horseradish peroxidase (HRP). Labeled cells were observed bilaterally (with a preponderance ipsilaterally) in nuclei intercalatus and praepositus hypoglossi following injections in various folia of the entire vermis, paraflocculus, flocculus, fastigial nucleus, and the nucleus interpositus anterior and posterior. Relatively high densities of labeled cells were found in nucleus intercalatus following injections in the anterior part of the vermis, whereas labeled cells in nucleus praepositus hypoglossi were found more frequently following injections in the posterior part of the vermis. Labeled cells in the nucleus of Roller were found only following injections in the anterior lobe vermis, posterior vermal lobules VI and VII, in the flocculus and in the nucleus interpositus anterior. No labeled cells could be detected in the three subdivisions of the perihypoglossal nuclei following HRP injections in crus I, crus II, paramedian lobule, and lateral cerebellar nucleus. The distribution of the HRP positive cells indicated the presence of a topographically organized projection from certain regions of the perihypoglossal nuclei to different parts of the cerebellum. The afferent and efferent connections of the perihypoglossal nuclei in relation to a functional role in eye and head movements are discussed.Abbreviations in Figures a,b,c sublobules of lobules V, VI and VII - f.apm. ansoparamedian fissure - f.icul. intraculminate fissure - f.in.cr. intercrural fissure - f.pc. preculminate fissure - f.pfl. parafloccular fissure - f.p.l. posterolateral fissure - f.ppd. prepyramidal fissure - f.pr. fissura prima - f.prc. precentral fissure - f.prc.a. precentral fissure a - f.p.s. posterior superior fissure - f.sec. fissura secunda - fl. flocculus - g.n. VII genu of facial nerve - HII-HVI, HIX hemispheral lobules II–VI, IX - HVIIA cr.Ia,p; cr.IIa,p anterior and posterior folia of crus I and II of the ansiform lobule - HVIIB, HVIIIA,B sublobules A and B of hemispheral lobules VII and VIII - ic nucleus intercalatus - l.ans. ansiform lobule - N.f. nucleus fastigii - Nfc nucleus cuneatus - Nfg nucleus gracilis - N.i.a. nucleus interpositus anterior - N.i.p. nucleus interpositus posterior - N.l. nucleus lateralis - pfl.d. dorsal paraflocculus - pfl.v. ventral paraflocculus - Ph nucleus praepositus hypoglossi - Ro nucleus of Roller - S solitary tract - s.int.cr.1,2 intracrural sulcus 1 and 2 - SL lateral nucleus of the solitary tract - SM medial nucleus of the solitary tract - VIN inferior vestibular nucleus - VLD lateral vestibular nucleus, dorsal division - VMN medial vestibular nucleus - I-VI vermian lobules I–VI - VI nucleus of abducent nerve - VIIA,B; VIIIA,B anterior and posterior sublobules of lobules VII and VIII - IX uvula - X dorsal motor nucleus of vagus nerve; nodulus - XII nucleus of hypoglossal nerve Parts of this paper were presented at the Symposium Control of Gaze by Brain Stem Neurons, Paris, July 13–15, 1977On leave from the Laboratory of Neurobiology, Faculty of Science, Mahidol University, Bangkok, Thailand, under NORAD Fellowship Program from the Norwegian Agency for International Development     

Peripheral injury and anterograde transport of wheat germ agglutinin-horse radish peroxidase to the spinal cord.

Previous observations have revealed labeling in the extracellular space surrounding boutons and unmyelinated fibers in superficial laminae of the spinal cord after injection of the tracer wheat germ agglutinin conjugated to horseradish peroxidase in dorsal root ganglia. The degree of extracellular labeling appeared related to the extent of the damage to the ganglia at the time of the injection. To determine whether injury might produce extracellular labeling, we investigated the effects of unilateral nerve crush or transection on spinal labeling after bilateral injections of the tracer into sciatic nerves. Confirming previous reports, labeling was confined to small dorsal root ganglion cells and to spinal laminae I and II, suggesting a selective affinity of this tracer for unmyelinated fibers. Labeling of both ganglion neurons and superficial spinal laminae was increased on the injured side, probably as a result of increased efficiency of receptor-mediated endocytosis. Electron microscopical observations revealed that the tracer was largely confined to unmyelinated dorsal root fibers bilaterally; a higher percentage of these fibers were labeled on the injured side. In the dorsal horn, the tracer was predominantly within unmyelinated axons and their terminals on the control side, whereas most of the labeling was extracellular and transneuronal on the injured side. The extracellular labeling surrounded unmyelinated fibers and their terminals in the spinal cord, but was excluded from the synaptic cleft. The demonstration that injury is accompanied by significantly increased release of this tracer from the terminals of unmyelinated fibers into the extracellular space suggests that endogenous substances may be released after peripheral lesions as a central signal of injury.     

Effects of kindling in wheat germ agglutinin-horseradish peroxidase [corrected] labeling in neurons of the interamygdaloid pathway in rats

This paper describes in kindled rats an increment in wheat germ agglutinin-horseradish peroxidase labeling in anterior commissure, bed nuclei of stria terminalis and amygdala. Three groups of animals were analyzed: control, sham-operated and kindled animals with ten convulsive generalized seizures. Results show that kindled animals have an increase in fiber labeling in anterior commissure and in the bed nuclei of stria terminalis, as well as a greater number of labeled neurons in amygdala. This label enhancement is related to the hyperexcitability of neurons produced by epilepsy, and could be associated to the propagation and formation of secondary foci and related plastic changes occurring during kindling.