Morphology of posterior canal related secondary vestibular neurons in rabbit and cat

The morphology of secondary vertical vestibular neurons was investigated by injection of horseradish peroxidase (HRP) into cells connected to the posterior canal system in rabbits (lateral-eyed animals) and cats (frontal-eyed animals). Vestibular neurons were identified by stimulation with bipolar electrodes implanted into the ampullae of the anterior and posterior (PC) semicircular canals of pigmented rabbits; in the cat, these cells were identified by natural and electrical stimulation. Axons monosynaptically activated by PC stimulation were injected with HRP in the medial longitudinal fasciculus (MLF). These were later reconstructed by light microscopy after the brains had been processed with a DAB-CoCl2 method. In the rabbit the majority of the axons bifurcated after crossing the midline with one branch ascending and the other descending in the MLF. The ascending branches gave rise to collaterals that terminated in both the trochlear nucleus and the inferior rectus subdivision of the oculomotor nucleus. In addition some axons also sent collaterals into the paramedian pontine reticular formation, the periaqueductal grey and the interstitial nucleus of Cajal. The descending branches were followed to the caudal part of the medulla in the MLF and gave rise to collaterals terminating in the vestibular nuclei, the medullary reticular formation, the perihypoglossal nuclei, the abducens nucleus, and the facial nucleus. In another cell type axons crossed the midline without giving off any collaterals and proceeded caudally in the caudal MLF. The synaptic effects of the two types of cells were concluded to be excitatory and inhibitory, respectively. Cell bodies of contralaterally projecting neurons were located in either the medial or ventro-lateral vestibular nuclei. In the cat we observed two neuron classes, with contralaterally projecting axons, whose synaptic effects are presumably excitatory. Their cell somata were located in the medial vestibular nucleus. Termination patterns were similar to both the trochlear and oculomotor nuclei, but neither projected to the abducens nucleus. One class of neurons was almost identical to that found in the rabbit with the main axon bifurcating in the MLF. The second type lacked a descending branch in the MLF. Axon collaterals of the latter type crossed the midline within the oculomotor nucleus after terminating in the inferior rectus subdivision to reach a similar portion of the ipsilateral oculomotor nucleus. Collaterals of these axons also terminated bilaterally in the supraoculomotor region between trochlear and oculomotor nucleus, the interstitial nucleus of Cajal and prerubral loci (including the fields of Forel). In similarity to the rabbit, presumed inhibitory vestibular neurons were found with axons directed caudally in the MLF without brain stem collaterals.(ABSTRACT TRUNCATED AT 400 WORDS)     

Morphology of vertical canal related second order vestibular neurons in the cat

Summary The morphology of vertical canal related second order vestibular neurons in the cat was studied with the intracellular horseradish peroxidase method. Neurons were identified by their monosynaptic potentials following electrical stimulation via bipolar electrodes implanted into individual semicircular canal ampullae. Anterior and posterior canal neurons projected primarily to contralateral or ipsilateral motoneuron pools (excitatory and inhibitory pathways, respectively). The axons of contralaterally projecting neurons crossed the midline at the level of the abducens nucleus and bifurcated into an ascending and a descending main branch which travelled in the medial longitudinal fasciculus (MLF). Two types of anterior canal neurons were observed, one with unilateral and one with bilateral oculomotor projection sites. For both neuron classes, the major termination sites were in the. contralateral superior rectus and inferior oblique subdivisions of the oculomotor nucleus. In neurons which terminated bilaterally, major collaterals recrossed the midline within the oculomotor nucleus to reach the ipsilateral superior rectus motoneuron pool. Other, less extensive, termination sites of both neuron classes were in the contralateral vestibular nuclear complex, the facial nucleus, the medullary and pontine reticular formation, midline areas within and neighboring the raphé nuclei, and the trochlear nucleus. The ascending main axons continued further rostrally to reach the interstitial nucleus of Cajal and areas around the fasciculus retroflexus. The descending branches proceeded further caudal in the medial vestibulo-spinal tract but were not followed to their spinal target areas. In addition to two previously described posterior canal related neuron types (Graf et al. 1983), we found neurons with bilateral oculomotor terminals and a spinal collateral. Typical for posterior canal neurons, the major termination sites were in the trochlear nucleus (superior oblique motoneurons) and in the inferior rectus subdivision of the oculomotor nucleus. Axon collaterals recrossed the midline to reach ipsilateral inferior rectus motoneurons. The axons of ipsilaterally projecting neurons ascended through the reticular formation to join the MLF caudal to the trochlear nucleus. The main target sites of anterior canal related neurons were in the trochlear nucleus and the inferior rectus subdivision of the oculomotor nucleus. Minor collaterals reached the pontine reticular formation and areas in between the fiber bundles of the ipsilateral MLF. In some cases, small collaterals crossed the midline within the oculomotor nucleus to terminate in the inferior rectus subdivision on the contralateral side. The axon proceeded further rostral to project to the interstitial nucleus of Cajal and beyond. The main termination sites of posterior canal neurons were in the superior rectus and inferior oblique subdivisions of the oculomotor nucleus. Minor collaterals were also observed to reach the midline area within the oculomotor nucleus, however, prospective contralateral termination sites could not be identified. More rostral projections were found in the interstitial nucleus of Cajal. The described axonal arborization of second order vestibular neurons reflects the organization of intrinsic coordinate systems as exemplified by the geometry of the semicircular canal and the extraocular muscle planes. These neurons are interpreted to provide a matrix for coordinate system transformation, i.e. from vestibular into oculomotor reference frames, and to play a role in gaze control and related reflexes by distributing their signals to multiple termination sites.Abbreviations DV descending vestibular nucleus - INC interstitial nucleus of Cajal - INT nucleus intercalatus - IQ inferior oblique subdivision - LV lateral vestibular nucleus - MLF medial longitudinal fasciculus - MRF medullary reticular formation - MV medial vestibular nucleus - nVII facial nerve - PH nucleus praepositus hypoglossi - PRF pontine reticular formation - RO nucleus Roller - SR superior rectus subdivision - SV superior vestibular nucleus - III oculomotor nucleus - IV trochlear nucleus - VI abducens nucleus - VII facial nucleus - XII hypoglossal nucleus Supported by NIH grants EY04613 and NS02619     

Vertical eye movement-related secondary vestibular neurons ascending in medial longitudinal fasciculus in cat. II. Direct connections with extraocular motoneurons

1. The preceding study in the alert cat has shown that many secondary vestibular axons that ascend in the medial longitudinal fasciculus (MLF) increase their firing rate in proportion to downward eye position. In the present study, projection and termination of these downward-position-vestibular (DPV) neurons within extraocular motoneuron pools were studied electrophysiologically by spike-triggered averaging techniques and morphologically be reconstructing their axonal trajectory after intra-axonal injection of horseradish peroxidase (HRP). 2. Extracellular field potentials recorded within the trochlear nucleus and/or the inferior rectus subdivision of the oculomotor nucleus were averaged by the use of spike potentials of single DPV neurons as triggers. All the crossed-DPV axons tested induced negative unitary field potentials in the trochlear nucleus (n = 9) and in the inferior rectus subdivision of the oculomotor nucleus (n = 5), suggesting that they made monosynaptic excitatory connection with motoneurons in these nuclei. The four crossed-DPV axons tested in the two motoneuron pools induced unitary field potentials in both. The majority of crossed-DPV axons terminated in these nuclei were directly activated from the caudal MLF, indicating that they had descending collaterals projecting to the spinal cord as well. The uncrossed-DPV axons did not induce such unitary field potentials either in the trochlear nucleus (n = 4) or in the inferior rectus subdivision (n = 3). 3. All the uncrossed-DPV axons examined (n = 14) induced positive unitary field potentials in the superior rectus subdivision of the oculomotor nucleus, suggesting that they made monosynaptic inhibitory connections with motoneurons innervating the superior rectus muscle. These uncrossed-DPV axons displayed regular firing patterns and were not activated from the caudal MLF. None of the crossed-DPV axons tested (n = 4) induced unitary field potentials in the superior rectus subdivision. 4. Five crossed-DPV axons were injected with HRP. All these axons ascended in the MLF contralateral to their soma, gave off many collaterals to the trochlear nucleus, and projected more rostrally. For three well-stained axons, numerous terminal branches were also found in the rostroventral part of the contralateral oculomotor nucleus, the area corresponding to the inferior rectus subdivision. Some collaterals in the oculomotor nucleus recrossed the midline to terminate in the medial part of the ipsilateral oculomotor nucleus. Other terminations were observed in the interstitial nucleus of Cajal and in the periaqueductal gray adjacent to the oculomotor nucleus. The crossed axons injected included both regular and irregular types, and three of the four examined were activated from the caudal MLF.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cerebellar afferents from neurons in the extraocular motor nuclei: a fluorescent retrograde double-labeling study in the sheep

The fluorescent retrograde double labeling technique has been used to identify within the extraocular motor nuclei of the sheep the neurons projecting to the cerebellum and to provide evidence whether they are motor neurons sending collaterals to the cerebellum or a separate population of neurons. The study was performed on eight sheep. The fluorescent tracers used were Fast Blue and the diamidino yellow dihydrochloride. In one and the same animal a fluorescent tracer was injected into the extraocular muscles (EOMs) and the other into bilateral points of the vermal folia II-V and paramedian lobule, or into the vermal folia VI, VIIA and VIIB, or into the underlying fastigial nuclei. Within the oculomotor, trochlear, and abducens nuclei, almost all of the motor neurons were labeled by the tracer injected into the EOMs and only a few cells were fluorescent for the tracer infiltrated into the cerebellum. These latter labelings were present bilaterally, and their number and distribution did not show apparent differences after injecting the paramedian lobule and the vermal folia or the fastigial nucleus. Along the rostrocaudal extent of the oculomotor and trochlear nuclei, the neurons projecting to the cerebellum were intermingled with the motor neurons located in the nuclear area facing the medial longitudinal fasciculus. In the abducens nucleus they were restricted to the caudal pole of the nucleus, which is located ventrolaterally to the genu of the facial nerve. Double-labeled neurons were never found. The absence of double-labeled cells, in spite of the efficiency of the tracer infiltration into the EOMs and into the cerebellum, demonstrates that the cerebellar projections from the extraocular motor nuclei are not collaterals of the motor neurons, but axons of a separate population of neurons.     

大鼠运动核内5-羟色胺1A、2A、5A受体的定位分布

为了阐明５ 羟色胺在中枢神经系统内与运动神经元结合的精确部位,本研究用免疫细胞化学技术分别观察了大鼠躯体运动核和内脏运动核内５ 羟色胺１Ａ、２Ａ、５Ａ 受体的定位分布。在躯体运动核内观察到：（１）５ 羟色胺１Ａ 受体样阳性神经元和纤维主要分布于动眼神经核、滑车神经核、三叉神经运动核、面神经核、舌下神经核和脊髓前角;（２）５ 羟色胺２Ａ 受体样阳性神经元主要见于动眼神经核、三叉神经运动核、面神经核、舌下神经核和脊髓前角,但阳性纤维和终末却密集地分布于三叉神经运动核、面神经核、舌下神经核和脊髓前角等处,除此之外动眼神经核、滑车神经核、展神经核和疑核内也能见到中等密度的阳性纤维和终末,纤维和终末的分布范围和染色浓度、密度都较神经元为明显;（３）少量淡染的５ 羟色胺５Ａ 受体样阳性神经元和稀疏的阳性纤维及终末主要见于三叉神经运动核、面神经核、舌下神经核和脊髓前角。在内脏运动核内观察的结果是：（１）动眼神经副交感核（Ｅ Ｗ 核）、上涎核、迷走神经背核、骶髓副交感核和胸髓侧角内仅有少量５ 羟色胺１Ａ 受体样阳性神经元、纤维和终末分布;（２）５ 羟色胺２Ａ 受体样阳性神经元和较密集的阳性纤维和终末见于Ｅ Ｗ 核、迷走神经背核、骶?     

Development of the oculomotor and trochlear nuclei in the Xenopus toad.

The development of the oculomotor and trochlear nuclei (nIII and nIV) was studied with the horseradish peroxidase (HRP) and the cobalt labelling techniques in Xenopus laevis tadpoles. The earliest labelling of the oculomotor neuroblasts was observed at stage 32. The ipsi- and contralateral nuclei were found in two distinct groups on either side of the brainstem and the oculomotor commissure formed by crossing axons was present at this early stage. The fusion of the two nuclei began at the late larval stage when the axonal outgrowth had been presumably completed. The trochlear neuroblasts could be first labelled at stage 39 when the position of the nucleus and axonal pathway was similar to the adult form.     

Cerebellar afferents from neurons in the extraocular motor nuclei: A fluorescent retrograde double‐labeling study in the sheep

The fluorescent retrograde double labeling technique has been used to identify within the extraocular motor nuclei of the sheep the neurons projecting to the cerebellum and to provide evidence whether they are motor neurons sending collaterals to the cerebellum or a separate population of neurons. The study was performed on eight sheep. The fluorescent tracers used were Fast Blue and the diamidino yellow dihydrochloride. In one and the same animal a fluorescent tracer was injected into the extraocular muscles (EOMs) and the other into bilateral points of the vermal folia II‐V and paramedian lobule, or into the vermal folia VI,VIIA and VIIB, or into the underlying fastigial nuclei. Within the oculomotor, trochlear, and abducens nuclei, almost all of the motor neurons were labeled by the tracer injected into the EOMs and only a few cells were fluorescent for the tracer infiltrated into the cerebellum. These latter labelings were present bilaterally, and their number and distribution did not show apparent differences after injecting the paramedian lobule and the vermal folia or the fastigial nucleus. Along the rostrocaudal extent of the oculomotor and trochlear nuclei, the neurons projecting to the cerebellum were intermingled with the motor neurons located in the nuclear area facing the medial longitudinal fasciculus. In the abducens nucleus they were restricted to the caudal pole of the nucleus, which is located ventrolaterally to the genu of the facial nerve. Double‐labeled neurons were never found. The absence of double‐labeled cells, in spite of the efficiency of the tracer infiltration into the EOMs and into the cerebellum, demonstrates that the cerebellar projections from the extraocular motor nuclei are not collaterals of the motor neurons, but axons of a separate population of neurons. Anat Rec 254:490–495, 1999. © 1999 Wiley‐Liss, Inc.     

Quantitative analysis of the feline dorsal column nuclei and their GABAergic and non-GABAergic neurons

Summary The gracile and internal and external cuneate nuclei of four adult cats were studied, using recently developed stereological techniques. The length, volume and position of the nuclei in relation to the level of obex were calculated, as well as the number of neurones, the neuronal density and volume of the three nuclei and different regions in the gracile and internal cuneate nucleus. Material processed for GABA immunocytochemistry was used in order to compare GABAergic and non-GABAergic neurones. The results demonstrate variations in the same nucleus in different animals, and in the nucleus of the left and right sides of the same animal. The same nucleus can vary up to 4 mm in its rostrocaudal position in relation to the obex. The mean sizes of the gracile, internal and external cuneate nuclei are 4.2, 8.4 and 5.6 mm', respectively and their mean neuronal numbers are about 52000, 76 000 and 33000, respectively. The neuronal density was highest (12907 cells/mm³) in the gracile, and lowest in the external cuneate nucleus (5987 cells/mm³). The external cuneate nucleus had a larger relative volume (7.9%) occupied by nerve cell bodies compared with the two medial nuclei (5.1% and 5.8%). In the gracile and internal cuneate nuclei, the GABAergic neurones constituted 28% and 25% of the whole population, respectively, while the external cuneate nucleus was devoid of such cells. All the nuclei contained GABA-positive boutons, however. The mean volume of the GABA-stained neurones in the gracile nucleus was 2319, and internal cuneate 3065 m³, while the corresponding volume of unlabelled neurones in the gracile, internal and external cuneate nuclei was 3745, 8147 and 13 318 m³, respectively. When cyto-fibro-architectonic characteristics were used to subdivide the gracile and cuneate nuclei into rostral, middle and caudal regions, and the data of the three compartments compared, it was found that in both nuclei the middle region had the highest neuronal packing density, and the caudal region the largest mean nerve cell volume.This paper is dedicated to Professor Fred Walberg on the occasion of his 70th birthday.     

Functional organization of the oculomotor nucleus in the baboon

The functional organization of the oculomotor nucleus was investigated using horseradish peroxidase (HRP) histochemistry. In a series of baboons, injections of HRP were made into the skeletal muscles supplied by the oculomotor nerve (medial rectus, superior rectus, inferior rectus, inferior oblique, and the levator palpebrae superioris). After a 48-hour survival time the animals were sacrificed via perfusion-fixation and the brains treated according to the tetramethylbenzidine (TMB)-HRP method of Mesulam (1978). The inferior oblique, inferior rectus, medial rectus, and levator palpebrae superioris muscles are supplied by cells located primarily in the homolateral oculomotor nucleus. Some fibers to the levator palpebrae superioris arise from cells in both caudal central nuclei. The superior rectus muscle receives fibers from cells in the contralateral oculomotor nucleus. The results were complied using a Lucite-plate reconstruction method that permits visualization of the three-dimensional configuration of the neuronal populations within the oculomotor nucleus. Oculomotor neurons are organized in a vertical column that may be anatomically divided into rostral, middle, and caudal thirds. A section through any of these levels may be further subdivided into dorsal, intermediate, and ventral zones. Each of the oculomotor skeletal muscles was found to have cells at almost all levels of the nucleus and in certain zones at each level. These functional cell groups intermingle with one another in the baboon and do not remain segregated into distinct subnuclei or subdivisions. Much overlap was evident between cells innervating the homolateral inferior rectus, homolateral inferior oblique, and the contralateral superior rectus muscles. There was also overlap between those cells supplying the homolateral levator palpebrae superioris and the homolateral medial rectus muscles.     

The oculomotor nuclear complex in humans: Microanatomy and clinical significance

This study has been performed to define better the anatomical structure of the oculomotor nuclear complex and its neuronal components.The oculomotor nuclear complex was examined in fixed and serially sectioned midbrains from 12 adult subjects free from neurological diseases. The complex included the somatic portion, (formed by multipolar motor neurons), and the parasympathetic portion, (formed by oval or fusiform preganglionic cells), on each side of the median raphe. The somatic portion consisted of the lateral somatic cell column and the caudal central nucleus. The somatic column measured from 0.2 × 0.1 mm to 3.4 × 1.4 mm (X = 2.4 × 1.2 mm) in transverse section. It was divided into the principal, intrafascicular and extrafascicular parts. The principal part was subdivided into the dorsal, intermediate and ventral portions. Isolated multipolar neurons were also found in the periaqueductal gray matter, the interstitial nucleus of Cajal, the Edinger-Westphal nucleus and the fibre bundles of the oculomotor nerve. These cells most likely represent the displaced motor neurons of the oculomotor nerve. The caudal central nucleus was 0.8 × 0.6 mm in size. The Edinger-Westphal nucleus consisted of the rostral, ventral and dorsal parts; the longest rostrocaudal diameter of this nucleus measured 7.1 mm. The anatomical data of our study are relevant clinically and allow explanation of the neurologic signs following complete or partial lesions of the oculomotor nuclear complex.     

Atlas of cholinergic neurons in the forebrain and upper brainstem of the macaque based on monoclonal choline acetyltransferase immunohistochemistry and acetylcholinesterase histochemistry

Choline acetyltransferase immunohistochemistry was used to map the cholinergic cell bodies in the forebrain and upper brainstem of the macaque brain. Neurons with choline acetyltransferase-like immunoreactivity were seen in the striatal complex, in the septal area, in the diagonal band region, in the substantia innominata, in the medial habenula, in the pontomecencephalic tegmentum and in the oculomotor and trochlear nuclei. The ventral striatum contained a higher density of cholinergic cell bodies than the dorsal striatum. All of the structures that contained the choline acetyltransferase positive neurons also had acetylcholinesterase-rich neurons. Choline acetyltransferase positive neurons were not encountered in the cortex. Some perikarya in the midline, intralaminar, reticular and limbic thalamic nuclei as well as in the hypothalamus were rich in acetylcholinesterase but did not give a positive choline acetyltransferase reaction. A similar dissociation was observed in the substantia nigra, the raphe nuclei and the nucleus locus coeruleus where acetylcholinesterase-rich neurons appeared to lack perikaryal choline acetyltransferase activity.     

Pathways and terminations of axons arising in the fastigial oculomotor region of macaque monkeys.

The majority of axons from the fastigial oculomotor region (FOR) decussated in the cerebellum at all rostrocaudal levels of the fastigial nucleus (FN) and entered the brainstem via the contralateral uncinate fasciculus (UF). Some decussated axons separated from the UF and ran medial to the contralateral superior cerebellar peduncle and ascended to the midbrain. Uncrossed FOR axons advanced rostrolaterally in the ipsilateral FN and entered the brainstem via the juxtarestiform body. The decussated fibers terminated in the brainstem nuclei that are implicated in the control of saccadic eye movements. In the midbrain, labeled terminals were found in the rostral interstitial nucleus of the medial longitudinal fasciculus, a medial part of Forel's H-field, the periaqueductal gray, the posterior commissure nucleus, and the superior colliculus of the contralateral side. In the pons and medulla, FOR fibers terminated in a caudal part of the pontine raphe, the paramedian pontine reticular formation, the nucleus reticularis tegmenti pontis, the dorsomedial pontine nucleus of the contralateral side, and the dorsomedial medullary reticular formation of both sides. In contrast, FOR projections to the vestibular complex were bilateral and were mainly to the ventral portions of the lateral and inferior vestibular nuclei. No labeled terminals were found in the following brainstem nuclei which are considered to be involved in oculomotor function: oculomotor and trochlear nuclei, interstitial nucleus of Cajal, medial and superior vestibular nuclei, periphypoglossal nuclei, and dorsolateral pontine nucleus. Labeling appeared in the red nucleus only when HRP encroached upon the posterior interposed nucleus.     

Vestibular projections to the nuclei of the extraocular muscles Degeneration resulting from discrete partial lesions of the vestibular nuclei in the monkey

In 35 monkeys attempts were made to produce localized unilateral lesions in individual vestibular nuclei in order to study vestibular projections to nuclei of the extraocular muscles. Portions of the medial, superior and inferior vestibular nuclei were destroyed selectively; lesions in Deiters' nucleus involved small portions of either the superior or inferior vestibular nuclei. Fiber degeneration was studied by the Nauta-Gygax technic. Exclusively ascending fibers from the superior vestibular nucleus project to ipsilateral extraocular nuclei. Ascending fibers from the inferior vestibular arise only from rostral portions of the nucleus, are not numerous and pass to all extraocular nuclei. The medial vestibular nucleus projects ascending fibers via the MLF bilaterally, asymmetrically and differentially to all extraocular nuclei. Prominent projections pass to: (a) the contralateral trochlear nucleus, and (b) the contralateral intermediate cell column and the ipsilateral ventral nucleus of the oculomotor complex. Ascending fibers from Deiters' nucleus, arising only from ventral portions of the nucleus, project primarily to: (a) the contralateral abducens and trochlear nuclei, and (b) specific asymmetrical portions of the oculomotor complex. Ascending vestibular fibers from the medial and lateral vestibular nuclei appear capable of mediating all patterned eye movements resulting from stimulation of ampullary nerves from individual semicircular canals. Vestibular projections to nuclei of the extraocular muscles are most abundant to those nuclei innervating muscles whose primary functions concern horizontal and rotatory eye movements.     

The time course of retrograde transsynaptic transport of tetanus toxin fragment C in the oculomotor system of the rabbit after injection into extraocular eye muscles

Summary The aim of this study was to determine the optimal survival time for labelling those neurons that monosynaptically terminate on extraocular motoneurons, i.e. the premotor neurons, after an injection of tetanus toxin fragment C, a retrograde transsynaptic tracer substance, into the eye muscle of the rabbit. Concentrated fragment C was injected into the inferior rectus or inferior oblique muscle and detected immunocytochemically in the brain after survival times of 8 h, 17 h, 2 d, 3 d, 4 d, 5 d, 6 d, 8 d and 12 d. Immunoreactivity was confined to granules within motoneuronal and premotor neuronal cell bodies, but became associated with punctate profiles outlining the somata with longer survival times. The strongest and most consistent labelling of premotor cell bodies was seen after 4 days survival time. The transsynaptic labelling pattern was shown to vary for individual premotor pathways.Abbreviations III oculomotor nucleus - IV trochlear nucleus - Vmes mesencephalic trigeminal nucleus - Vmt motor trigeminal nucleus - VI abducens nucleus - VIacc accessory abducens nucleus - VII facial nucleus - BC brachium conjunctivum, co cochlear nucleus - CR restiform body - d dentate nucleus - DAB diamino-benzidine-tetrahydrochloride - HRP horseradish peroxidase - iC interstitital nucleus of Cajal, iv inferior vestibular nucleus - lgn_d lateral geniculate nucleus dorsalis - lgn_v lateral geniculate nucleus ventralis - lv lateral vestibular nucleus - mgn medial geniculate nucleus - MLF medial longitudinal fasciculus - mv_p medial vestibular nucleus pars parvocellularis - mv_m medial vestibular nucleus pars magnocellularis (= ventral part of the lv) - NIII oculomotor nerve - NV trigeminal nerve - NVII facial nerve - NVIII vestibular nerve - PC posterior commissure - pg periaquaeductal grey - ppH nucleus praepositus hypoglossi - riMLF rostral interstitial nucleus of the medial longitudinal fasciculus - rn red nucleus - sc superior colliculus - sn substantia nigra - so superior olive - sv superior vestibular nucleus - sv_c superior vestibular nucleus contralateral - sv_i superior vestibular nucleus ipsilateral - TR tractus retroflexus - Y Y-group zi zona incerta     

脑神经海绵窦段的显微解剖及其临床应用

目的　为海绵窦 (cavernoussinus,CS)直接手术提供解剖学基础。方法　在手术显微镜下对 15例 (30侧 )成人头颅标本CS内脑神经位置、行径以及与颈内动脉CS段的毗邻关系进行观测。结果　①动眼神经入窦点在前床突尖后方 (4 5 7± 1 0 5 )mm ,与滑车神经、眼神经垂直距离分别为 (2 2 0± 0 6 7)mm和 (4 37± 1 35 )mm。②滑车神经入窦点与眼神经垂直距离为 (5 5 2± 1 0 6 )mm。滑车神经CS段行程形状可分为三型。③颈内动脉后曲顶高出眼神经和展神经上缘分别为 (5 5 2± 1 84)mm和 (6 6 0± 1 94)mm。④经前床窦尖外侧或外下方时 ,动眼神经、滑车神经及眼神经与前床突尖垂直距离分别为 (1 85±0 75 )mm、(5 30± 1 0 4)mm和 (6 6 1± 1 6 3)mm。结论　掌握脑神经CS段的显微解剖对CS的直接手术具有重要意义。     

Operational unit responsible for plane-specific control of eye movement by cerebellar flocculus in cat

1. Main findings in our previous studies are as follows: 1) there are three Purkinje cell zones running perpendicular to the long axis of the folia in the cat flocculus, 2) the caudal zone controls activity of the superior rectus (SR) and inferior oblique (IO) extraocular muscles via the y-group and oculomotor nucleus (OMN) neurons, and 3) the middle zone controls activity of the lateral (LR) and medial rectus (MR) muscles via the medial vestibular (MV) and abducens nucleus (ABN) neurons. In the present study, the neuronal pathways from the remaining rostral zone were investigated in the anesthetized cat. 2. Target neurons of rostral zone inhibition in the superior vestibular nucleus (SV) were identified by observing cessation of spontaneous discharges after rostral zone stimulation. Efferent projections were studied by the use of systematic microstimulation techniques. Unitary responses to stimulation of the eighth nerves were also investigated. 3. There are two types of the target neurons: 1) those, being located in the central and dorsal parts of the SV, project to the trochlear and oculomotor nuclei innervating superior oblique and inferior rectus muscles via the ipsilateral medial longitudinal fasciculus (MLF); and 2) those, being located along the dorsal border of the SV, project to the contralateral oculomotor nucleus innervating superior rectus and inferior oblique muscles via the extra-MLF route. 4. Both types receive monosynaptic anterior canal nerve input but not posterior canal nerve input. Some neurons receive polysynaptic excitatory input from the contralateral eighth nerve, although commissural inhibition was never observed. 5. From neuronal connections of the rostral and caudal zones and action of the extraocular muscles, it was expected that 1) activity changes of Purkinje cells in the rostral and/or caudal zones on one side resulted in conjugate eye movement in the plane of the anterior canal on the side of the activity changes, 2) cooperative increased activity on both sides resulted in conjugate downward eye movement, and 3) increased activity on one side and decreased activity on the other side resulted in conjugate rotatory eye movement. The rostral and caudal zones may be responsible for eye-movement control in the sagittal plane by cooperative activity changes on both sides and in the transverse plane by reciprocal activity changes on both sides. For eye-movement control in the anterior canal plane, Purkinje cell activity on one side would be sufficient to produce the required movement. In a functional sense, we call the rostral and caudal zones, the vertical-plane zones.(ABSTRACT TRUNCATED AT 400 WORDS)     

Properties of utricular nerve-activated vestibulospinal neurons in cats

The axonal pathway, conduction velocities, and locations of the cell bodies of utricular nerve-activated vestibulospinal neurons were studied in decerebrated or anesthetized cats using the collision test of orthodromic and antidromic spikes. For orthodromic stimulation, bipolar tungsten electrodes were placed on the utricular nerve and the other vestibular nerve branches were transected. Monopolar tungsten electrodes were positioned on both sides of the upper cervical segments (C2–4), caudal end of the cervical enlargement (C7-T1), and from the lower thoracic to the upper lumbar segments (T12-L3) and were used for antidromic stimulation of the spinal cord. Another monopolar electrode was also placed in the oculomotor nucleus to study whether utricular nerve-activated vestibulospinal neurons have ascending branches to the oculomotor nucleus. Of the 173 vestibular neurons orthodromically activated by the stimulation of the utricular nerve, 46 were second-order vestibulospinal neurons and 5 were third-order neurons. The majority of the utricular nerve-activated vestibulospinal neurons were located in the rostral part of the descending vestibular nucleus and the caudal part of the ventral lateral nucleus. Seventy-three percent of the utricular nerve-activated vestibulospinal neurons descended through the ipsilateral lateral vestibulospinal tract. Approximately 80% of these neurons reached the cervicothoracic junction, but a few reached the upper lumbar spinal cord. Twenty-seven percent of the utricular nerve-activated vestibulospinal neurons descended through the medial vestibulospinal tract or the contralateral vestibulospinal tracts. Those axons terminated mainly in the upper cervical segments. Almost none of the utricular nerve-activated vestibular neurons had ascending branches to the oculomotor nucleus.     

Projections from the superior colliculus to a region of the central mesencephalic reticular formation (cMRF) associated with horizontal saccadic eye movements

Summary Radioactive wheatgerm agglutinin (WGA) and horseradish peroxidase (HRP) were injected into portions of the mesencephalic reticular formation at sites where electrical stimulation induced either small or large contralateral horizontal saccadic eye movements. We have designated this region as the Central MRF (cMRF). It contains both cells and fiber tracts, including the efferent output of the superior colliculus (SC), destined for the dorsal tegmental decussation and the predorsal bundle. Cells labelled by WGA and HRP injections were found in the intermediate and deep layers of the superior colliculus and the adjacent central gray matter on the ipsilateral side. Injections into the dorsal cMRF, at sites where small saccades were induced, caused labelling of cells in the rostral intermediate layer of SC. Injections into the ventral cMRF, at points where large saccades were elicited, caused labelling of cells in the caudal intermediate layer of SC. The deepest layers of SC and the adjacent central gray were also labelled from the small eye movement region of dorsal cMRF. We interpret these findings to indicate that the intermediate layers of SC send axonal projections to the horizontal eye movement region of the MRF in a topographic fashion. The projection from the intermediate layer is organized so that regions in SC and cMRF related to small or to large eye movements are interconnected. The results support the hypothesis that cMRF is a topographically organized area, involved, like SC, in the control of eye movements. Since both cMRF and the superior colliculus project to areas of the pons and medulla where saccadic eye movements are produced, they could give rise to parallel pathways for the generation of contralateral saccades.Abbreviations III oculomotor nucleus - IV trochlear nucleus - ap area pretectalis - BC brachium conjunctivum - BSC brachium of the superior colliculus - cg central gray - cMRF central MRF - d deep layer of SC - DAB diaminobenzidine - EOG electro-oculography - h habenula nuclei - HRP horseradish peroxidase - iC interstitial nucleus of Cajal - ic inferior colliculus - li nucleus limitans - mg medial geniculate body - MLF medial longitudinal fasciculus - nIII oculomotor nerve - nIV trochlear nerve - on olivary nucleus - p pulvinar - PC posterior commissure - riMLF rostral interstitial nucleus of the MLF - rn red nucleus, pars magnocellularis - rnp red nucleus, pars parvocellularis - s superficial layer of SC - SC superior colliculus - sl sublentiform nucleus - sn substantia nigra - TMB tetramethyl benzidine - TR tractus retroflexus - WGA wheatgerm agglutinin Supported by NIH Research grant EY 02296, Deutsche Forschungsgemeinschaft grant SFB 200/A3 and Core Center grant EY 01867     

A morphometric study of myocytes of normal and hypertrophic human atria

Morphometric study of myocytes of normal and hypertrophic human atria was performed in semithin and paraffin sections. The hypertrophy is followed by the increase of size of both the myocytes and their nuclei: the average nuclei diameter increases from 5.9 to 7.5 microns, the average length from 13.7 to 20.2 microns. The same parameters of the cell change from 13.5 to 18.5 microns and from 121.6 to 143.9 microns. The increase of the nuclei length correlates with the increase of its ploidy. The ratio nucleus cytoplasm remains unchanged as well as the ratio between muscles and connective tissue. The number of binucleated cells in the hypertrophied atrium increases by factor of 3 or 4. The number of myocytes in the atrium was calculated and was equal to 1790.10(6) +/- 241.10(6) under normal conditions and 1890.10(6) +/- 336.10(6) in case of hypertrophy. The mechanisms of the heart weight increase is discussed.     

Nerve cell clusters in dorsal striatum and nucleus accumbens of the male rat demonstrated by glucocorticoid receptor immunoreactivity

Glucocorticoid receptor-immunoreactive nerve cells have been analysed in the dorsal striatum and nucleus accumbens of the rat by means of a monoclonal antibody against rat liver glucocorticoid receptor. Glucocorticoid receptor immunoreactivity was present in the nuclei of the vast majority of the striatal nerve cells. The analysis of sections stained with glucocorticoid receptor antibody and cresyl violet showed that around 90% of the entire striatal neuronal population contained glucocorticoid receptor immunoreactivity. By means of the double immunoperoxidase technique evidence was provided that somatostatin- and choline acetyltransferase-immunoreactive nerve cells in the striatum do not contain glucocorticoid receptor immunoreactivity. The density of glucocorticoid receptor-immunoreactive nerve cells in the grey matter and the presence of clusters of glucocorticoid receptor-immunoreactive nerve cells have been investigated in three fields located in the medial and central dorsal striatum and nucleus accumbens at the coronal level A 8620 microns according to the K?nig and Klippel atlas using computer-assisted image analysis. Every aggregate containing three or more glucocorticoid receptor-immunoreactive nerve cells, which had an intercenter distance less than the mean diameter (10-11 microns) of the striatal cells, was considered an island. A higher density of both glucocorticoid receptor-immunoreactive nerve cell nuclei and islands was found in the nucleus accumbens with respect to dorsal striatal areas. The most frequent island formed consisted of three to ten nerve cells both in dorsal striatum and nucleus accumbens. Furthermore, some nucleus accumbens islands contained up to 100 nerve cells, whereas in the dorsal striatum the maximum number of glucocorticoid receptor-immunoreactive nerve cells per island ranged from 50 to 60. The present procedure proved to be a sensitive method to reveal clusters of chemically identified structures and provided evidence for a basic cytoarchitectonic organization of the dorsal striatum and nucleus accumbens of the rat. This paper also demonstrated that the vast majority, but not all, striatal nerve cells contained glucocorticoid receptor immunoreactivity, and thus may be under the control of circulating glucocorticoids. In fact, only small transmitter-identified neuronal populations, such as somatostatin- and choline acetyltransferase-immunoreactive nerve cells, were devoid of glucocorticoid receptor immunoreactivity.