大白鼠三叉神经核至小脑皮层的纤维投射—HRP法研究

用大白鼠13只,以微电泳方法把HRP分区导入到小脑皮层,研究三叉神经核至小脑皮层的纤维投射。结果表明,单叶、脚Ⅰ、脚Ⅱ、旁正中小叶、背侧旁絮叶、Ⅷ小叶外侧部和Ⅵ—Ⅺ小叶的蚓部皮层均接受双侧(同侧为主)三叉神经核的纤维投射。三叉神经脊束核中间亚核和三叉神经感觉主核向小脑的投射区最广,包括上述的全部区域。三叉神经脊束核尾侧亚核投射到小脑的脚Ⅰ、旁正中小叶、背侧旁絮叶、Ⅷ小叶的外侧部和Ⅵ—Ⅸ小叶的蚓部皮层。三叉神经脊束核吻侧亚核仅投射到脚Ⅱ、旁正中小叶、Ⅷ小叶外侧都和Ⅷ—Ⅸ小叶的蚓部皮层。三叉神经中脑核投射到脚Ⅰ、脚Ⅱ、旁正中小叶、Ⅷ小叶外侧部和Ⅶ—Ⅸ小时的蚓部皮层。在三叉神经运动核内只发现很少的几个标记细胞,但在运动核的腹外侧,三叉神经根中及其附近,全部例子均看到有大量的标记细胞。在一例带有三叉神经半月节的脑干切片中,意外地观察到在半月节内有数个标记细胞。     

大白鼠三叉神经核至小脑皮层的纤维投射——HRP法研究

本实验用大白鼠13只,以微电泳法将HRP导入到小脑皮层各区,研究三叉神经核至小脑皮层的纤维投射。结果表明:单叶、脚Ⅰ、脚Ⅱ、旁正中小叶、背侧旁絮叶、Ⅷ小叶的外侧部和Ⅵ～Ⅸ小叶的蚓部皮层均接受双侧(同侧为主)三叉神经核的纤维投射。三叉神经脊束核极间亚核和三叉神经感觉主核向小脑的投射包括上述的全部区域。三叉神经脊束核尾侧亚核投射到小脑的脚Ⅰ、旁正中小叶、背侧旁絮叶、Ⅷ小叶的外侧部和Ⅵ～Ⅸ小叶的蚓部皮层。三叉神经脊束核吻侧亚核仅投射到脚Ⅱ、旁正中小叶、Ⅷ小叶的外侧部和Ⅶ～Ⅸ小叶的蚓部皮层。三叉神经中脑核投射到脚Ⅰ、脚Ⅱ、旁正中小叶、Ⅷ小叶的外侧部和Ⅶ～Ⅸ小叶的蚓部皮层。在三叉神经运动核内,只发现几个标记细胞,但在运动核的腹外侧、三叉神经根中及其附近,所有例子均看到有大量的标记细胞。在一例三叉神经半月节中,意外地观察到有数个标记的节细胞。     

大白鼠前脑、脑干和小脑向孤束核的纤维投射——HRP法和ARG法研究

本实验用HRP法、WGA—HRP法和ARG法进一步研究了大白鼠前脑、脑干和小脑向孤束核的纤维投射及其局部定位关系。作者发现皮质32及8区、三叉神经脊束核尾侧亚核投射到孤束核头段;皮质24及8a区、三叉神经脊束核尾侧亚核投射到孤束核中段;皮质23及13区,中脑导水管周围灰质和三叉神经脊束核尾侧亚核投射到孤束核尾段。此外,结果还证明室旁核、下丘脑外侧区、兰斑核、K—F氏核、小脑顶核、中缝大核、网状大细胞核、外侧网状核、及延髓网状结构向孤束核的纤维投射,均存在着一定的局部定位关系。本文结合前脑、脑干向孤束核的纤维投射讨论了内脏活动调节及针刺镇痛效应的中枢机理并对大白鼠孤束核的分段(头、中及尾段)标准提出了新建议。     

大鼠三叉神经脊束核吻侧亚核背内侧部及邻接的外侧网状结构的传出投射——WGA-HRP顺行追踪研究(中脑核—丘脑投射通路研究之二)

在已探明三叉神经中脑核神经元中枢突向三叉神经脊束核吻侧亚核的背内侧部(Vodm)及邻接的网状结构(LRF)投射的基础上,本文作者用WGA—HRP顺行标记法追踪了Vodm和其邻接的LRF传出投射的终止部位,以期探索Vme—丘脑通路中第三级神经元的所在。结果发现Vodm及邻接的LRF除投射到一些脑神经运动核、臂旁核、下橄榄主核腹肢内端外,还发现了前人未曾注意到的沿三叉神经感觉主核内缘存在且向腹侧伸延的一个带状区内有浓密的标记终末终止。此标记终末带区在上橄榄核背侧,三叉神经运动核腹侧以及三叉神经感觉主核的背内侧部等处增大,而上橄榄核背侧及三叉运动核腹侧的终末区以往并无人注意到在此有与之相应的核团。     

猫丘脑中央外侧核的皮质下传入联系

本实验用HRP逆行性轴浆运输技术,对猫丘脑中央外侧核的传入纤维联系及其局部定位关系进行了观察。投射至丘脑中央外侧核尾侧区的主要核团包括:外侧膝状体腹核背侧带、丘脑网状核特别是它的背侧部、上丘深层,以同侧为主。板内核、丘脑下部外侧区和黑质网状部神经元的轴突终止在同侧丘脑中央外侧核吻侧区。丘脑中央外侧核全长的传入起自脑干网状结构和前庭神经核,呈双侧投射。前者以同侧为主,后者以对侧占优势。同侧未定带,顶盖前区、动眼神经核周围的细胞群、对侧三叉神经感觉主核、楔束核、薄束核以及小脑齿状核内也含有少量标记细胞。我们还观察到HRP注射中心区位于中央外侧核并扩散至丘脑腹前核者,同侧脚内核含大量HRP阳性细胞,而Gudden被盖腹侧核内充满密集的标记终末。这些结果表明,丘脑中央外侧核可能涉及多种感觉和运动功能。     

大鼠三叉神经脊束核尾侧亚核和脊髓向丘脑和臂旁核的谷氨酸能投射

本研究用荧光金逆行追踪与免疫荧光组比技术相结合的方法,对大鼠三叉神经脊束核尾侧亚核和脊髓向丘脑和臂旁核的谷氨酸能投射进行了观察。磷酸激活的谷氨酸胺酶（PAG）是谷氨酸能神经元的特异性标识物。PAG样阳性胞体主要位于三叉神经脊束核尾侧亚核和颈髓背角的Ⅰ层,少量PAG样阳性胞体也见于它们的Ⅱ层外侧部及外侧网状核。将荧光金注入丘脑腹基底复合体后．荧光金逆标神经元主要见于对侧三叉神经脊束核尾侧亚核和颈髓背角的Ⅰ层及外侧网状核;将荧光金注入臂旁核后,荧光金逆标神经元也主要见于对侧三叉神经脊束核尾侧亚核和颈髓背角的Ⅰ层及外侧网状核。三叉神经脊束核尾侧亚核向丘脑腹基底复合体投射神经元的12．4％,向臂旁核投射神经元的13．2％呈PAG样阳性;颈髓背角浅层向丘脑瓜基底复合体投射神经元的12．7％,向臂旁核投射神经元的14．3％呈PAG样阳性。向丘脑腹基底复合体和臂旁核投射的PAG／荧光金双标神经元分别占三叉神经脊束核尾侧亚核浅层内PAG样阳性神经元总数的13％和24．6％,向丘脑腹基底复合体和臂旁核投射的PAG／荧光金双标神经元分别占颈髓背角浅层内PAG样阳性神经元总数的11．6％和30．1％。外侧网状核内的部分PAG样阳性神经元也向丘脑腹基底复合体或臂旁核投射。Ⅰ层内的双?     

三叉神经初级传入纤维的中枢投射——HRP跨节追踪研究

分别向猫眶上神经、眶下神经和下牙槽神经的神经干内注射20％HRP(Toyobo,RZ 3.3)溶液,跨节追踪了三叉神经初级传入纤维在中枢内的分布。 1.三叉神经的初级传入纤维在中枢内都与三叉神经感觉核簇发生全面的联系。其中,眶上神经向三叉神经脊束核的尾侧亚核第Ⅰ～Ⅴ层都有大量的投射,而向吻侧,则标记终末只位于各亚核腹侧的极小范围内。眶下神经在三叉神经感觉核簇中的标记终末分布范围较大,以尾侧亚核的中央部和感觉主核腹侧2/3部的标记终末最为密集。下牙槽神经在尾侧亚核和吻侧亚核的标记终末数量和分布范围最大。 2.含有大量来自额部皮肤和上颌胡须的触觉传入纤维的眶上、眶下神经除向感觉主核投射外,也向其它各亚核特别是尾侧亚核有大量的投射。含有较大量痛觉传入纤维的下牙槽神经不仅向脊束核投射,在感觉主核的投射也是明显的。因而,确证了感觉主核接受触觉,脊束核接受痛温觉传入投射的传统看法是不符合实际的。 3.上述三神经都向尾侧亚核内侧相当于脊髄后角第Ⅴ层的区域有明显的投射。结合文献,本文作者支持此第Ⅴ层应归属于尾侧亚核的看法,并推论此区可能有三叉神经传入纤维和其它脑结构来源的纤维的汇聚。     

大鼠小脑—丘脑投射的起源和终止——HRP法研究

本实验用HRP法研究了大鼠小脑—丘脑投射的起源和终止。大鼠所有小脑核(齿状核DN、间位核前部 AIN、间位核后部 PIN 及顶核 FN)都发出纤维投射到丘脑,其中 DN 投射的范围最广,其次是PIN及AIN,FN较小。大鼠小脑—丘脑投射终止在对侧丘脑的腹侧核群(腹前核VA、腹外侧核VL、腹内侧核VM及腹后外侧核VPL),内侧核群(中央外侧核CL、束旁核Pf及背内侧核MD)以及后核群(内侧膝状体MGB、丘脑后核PO)。小脑DN到丘脑腹侧核群的投射有相应的颅尾局部定位关系,但有部分重叠。FN到丘脑的投射仅起自FN的尾侧部,投射到丘脑的VM、VPL、CL、Pf及PO。除AIN外,小脑的DN、PIN及FN均有少量纤维投射到同侧的丘脑VM、CL及Pf。     

大鼠中缝大核下行投射纤维与三叉神经脊束核尾侧亚核向丘脑投射神经元之间的突触联系

本研究分别用逆行和顺行追踪相结合及逆行追踪与免疫组织化学反应相结合的双标记技术对中缝大核下行投射纤维和５ ＨＴ 样阳性终末在三叉神经脊束核尾侧亚核内的分布及其与向丘脑投射神经元之间的突触联系进行了观察。将ＨＲＰ注入丘脑腹后内侧核,证明ＨＲＰ逆标神经元主要见于三叉神经脊束核尾侧亚核的Ⅰ、Ⅲ层;将顺行标记物ＰＨＡ Ｌ 注入中缝大核,证明ＰＨＡ Ｌ顺标纤维和终末也主要见于尾侧亚核的Ⅰ层,Ⅱ层内仅有少量ＰＨＡ Ｌ 顺标终末;免疫组织化学反应的结果显示５ ＨＴ 样阳性终末也主要存在于尾侧亚核的Ⅰ和Ⅱ层,其它部位仅散在分布。在电镜下观察到：（１）三叉神经脊束核尾侧亚核Ⅰ层的ＨＲＰ逆标神经元的胞体和树突分别与ＰＨＡ Ｌ顺标终末形成轴 体突触和轴 树突触,其中大部分为对称性突触,非对称性突触较少;（２）尾侧亚核Ⅰ层ＨＲＰ逆标神经元的胞体和树突也分别与５ ＨＴ 样阳性终末形成轴 体突触和轴 树突触,这些突触联系也以对称性突触为主。本研究的结果表明：中缝大核的下行投射纤维主要终止于三叉神经脊束核尾侧亚核Ⅰ层,对此层内向丘脑投射的神经元可能主要发挥抑制作用,而５ ＨＴ 是中缝大核下行投射纤维的主要神经活性物质。     

大鼠中脑中央灰质和背中缝核向伏核和三叉神经脊束核尾侧亚核的分枝投射——荧光素双标法研究

<正> 本文应用荧光素双标法研究了大鼠中脑中央灰质和背中缝核向伏核和三叉神经脊束核尾侧亚核的分枝投射。将双苯甲胺(Bb)和碘化丙啶(PI)分别定向注入同侧的三叉神经脊束核尾侧亚核和伏核后,在中脑中央灰质和背中缝核内见到双标细胞和二种单标细胞。双标细胞占三种标记细胞总数的9％,PI单标细胞占58％,Bb单标细胞占33％。双标细胞位于中脑中央灰质中、尾段的腹外侧区,内侧区腹侧部及背中缝核内;PI单标细胞的分布基本上同     

Cerebellotectal projections studied in cats with horseradish peroxidase or tritiated amino acids axonal transport

Summary After injections of horseradish peroxidase (HRP) into various parts of the superior colliculus (SC) in 14 cats, retrogradely labeled neurons were found in parts of all deep cerebellar nuclei. The present study demonstrated that there are three main origins of the cerebellotectal projections in regard to the locations of the cell bodies: (1) the caudal half approximately of the fastigial nucleus (NM) including the subnucleus medialis parvocellularis (SMP), (2) the ventral and lateral parts of the posterior interpositus nucleus (NIP), and (3) the ventral part of the dentate nucleus (NL) including the subnucleus lateralis parvocellularis (SLP).The pathways and terminations of these projections have also been shown autoradiographically. Thus, fibers from NM crossed within the cerebellum and terminated in the intermediate and deep gray layers of the bilateral SC. Fibers from NIP and NL passed within the superior cerebellar peduncle, which crossed in the tegmentum (decussation of the peduncle) and ended in the two layers of the contralateral SC. In addition, some cerebellofugal fibers were found to terminate in the nuclei interstitialis of Cajal and Darkschewitsch, as well as in parts of pretectum and thalamus.The tecto-ponto- (and olivo-) cerebellotectal loop (cf. Kawamura 1980) has been established morphologically and it is briefly commented on in correlation with the propagation of the teleceptive (optic and acoustic) impulses.Abbreviations AI Stratum album intermedium - AP Stratum album profundum - Cc Crus cerebri - CM Corpus mamillare - EW Nucleus of Edinger-Westphal - f.apm. Ansoparamedian fissure - Flm Fasciculus longitudinalis medialis - f.p.l. Posterolateral fissure - f.ppd. Prepyramidal fissure - f.pr. Fissura prima - f.p.s. Posterior superior fissure - f.sec. Fissura secunda - GI Stratum griseum intermedium - GP Stratum griseum profundum - GS Stratum griseum superficiale - L. Left - MG Medial geniculate body - ND Nucleus of Darkschewitsch - NIA Nucleus interpositus anterior - Nint Nucleus interstitialis of Cajal - NIP Nucleus interpositus posterior - NL Nucleus lateralis (dentatus) - NL-NIA Transition area of nucleus lateralis (dentatus) and nucleus interpositus anterior - NM Nucleus fastigii - Npa Nucleus pretectalis anterior - Npc Nucleus of posterior commissure - Npm Nucleus pretectalis medialis - Npp Nucleus pretectalis posterior - NR Nucleus ruber - Nto Nucleus of optic tract - N.III Oculomotor nerve - O Stratum opticum - PC Posterior commissure - pm. Paramedian lobule - Pg Periaqueductal gray substance - R. Right - Rf Fasciculus retroflexus - SC Superior colliculus - SCC Commissure of SC - Z Stratum zonale - III Nucleus of oculomotor nerve - V, VI, VIIA, VIIB, VIIIA, VIIIB, IX Cerebellar lobules of Larsell Working in the Anatomical Department of Iwate Medical University for six months (several periods during the year 1981)     

The interposito-rubrospinal system. Anatomical tracing of a motor control pathway in the rat

The cerebello-rubromotor pathway, impinging on both spinal and facial motor nuclei, has been traced in the rat, using the bidirectional transport of horseradish peroxidase-wheat germ agglutinin conjugate. After injection of the tracer in the red nucleus (NR), retrograde labelling shows a topical arrangement of the cerebellorubral connection. The nucleus lateralis projects to the parvocellular NR (NRp) and the nucleus interpositus to the magnocellular NR (NRm). The nucleus interpositus anterior (NIA) reaches the entire NRm and this projection is topographically arranged: the medial NIA sends fibres ventrally, the lateral NIA dorsally. The medial two-thirds of the nucleus interpositus posterior (NIP) project only to the medial aspect of the NRm, with no apparent organization. No connection has been found between the lateral third of NIP and the NRm. After injection of the tracer in the spinal cord or the nucleus of the facial nerve, retrograde labelling is observed almost throughout the entire caudorostral extent of the NR, although labelling is more scant in NRp than in NRm. Rubrospinal and rubrofacial projections are somatotopically arranged in the dorsoventral direction: ventrolateral regions of NR reach the lumbar cord, medioventral regions the lower cervical levels, intermediary regions the upper cervical levels and finally the dorsalmost part of the NR projects to the nucleus of the facial nerve. After injection of the tracer in the cerebellar nuclei, anterograde labelling in the NR shows that interpositorubral connections determine two subregions in the NR: a lateral one under the exclusive control of the NIA, and a medial one under the control of both NIA-NIP afferents. It confirms in addition the topography of the NIA-NRm projection and shows the preponderant participation of the NIA afferents to the interpositorubral connection. Thus, it appears from our results that the cerebellorubral arrangement matches, to a great extent, the "rubromotor" efferent organization.     

Spinal projections to the cerebellar nuclei in the cat

Summary Projections from the spinal gray matter to the cerebellar nuclei in the cat have been studied using Nauta's silver technique. Following unilateral section of the ventrolateral cord at the cervical level, heavy degeneration is seen in the nucleus medialis on both sides. Scanty degeneration is present bilaterally in the nucleus interpositus. The degeneration is most intense on the contralateral side. Scanty degeneration is also present bilaterally in subnucleus medialis parvicellularis (SMP) (Flood and Jansen, 1961). No degeneration is seen in nucleus lateralis. Following unilateral section of the dorsolateral cord at the cervical level, scanty degeneration is present bilaterally in nucleus medialis and nucleus interpositus anterior. The degeneration is more pronounced ipsilaterally and is also seen in SMP on both sides. No degeneration is present in nucleus lateralis. Fibers from the ventral and dorsal spinocerebellar tracts (VSCT and DSCT) terminate bilaterally in nuclei medialis and interpositus, with the VSCT as the most important connection.     

Somatotopical organization of the projection from the nucleus interpositus anterior of the cerebellum to the red nucleus. An experimental study in the cat with silver impregnation methods

Summary Small lesions were done in various areas of the nucleus interpositus anterior (NIA) of the cerebellum, and the distribution of terminal degeneration was studied in the red nucleus with the methods of Nauta and Glees. The NIA projects to the contralateral red nucleus. Two principles of organization can be demonstrated in the projection: a caudorostral arrangement in the red nucleus corresponds to a mediolateral organization in the NIA and a mediolateral arrangement in the red nucleus corresponds to a caudorostral organization of the NIA. The latter distribution coincides with the somatotopical areas of the red nucleus defined by Pompeiano and Brodal (1957). Special attention has been paid to the questions of the subdivision of the cerebellar nuclei and of the course of the fibres issuing from the nuclei in the cerebellar hilus. The present findings on the projection of the NIA to the red nucleus have been correlated with recent anatomical and physiological data on the cerebellum and the red nucleus.Abbreviations BC brachium conjunctivum - c caudal - d dorsal - Ext extensor effects - Flex flexor effects - forel forelimb area - HB hook-bundle - Hb. P habenulo-peduncular tract - hindl hindlimb area - I lateral - m medial - NF nucleus fastigii or medialis - NIA nucleus interpositus anterior - NIP nucleus interpositus posterior - NL nucleus lateralis - r rostral - v ventral - III root fibres of the third nerve - IV fourth ventricle Fellow of the Canadian Medical Research Council.     

An analysis of potentially converging inputs to the rostral ventral thalamic nuclei of the cat

Summary Potentially convergent inputs to cerebellar-receiving and basal ganglia-receiving areas of the thalamus were identified using horseradish peroxidase (HRP) retrograde tracing techniques. HRP was deposited iontophoretically into the ventroanterior (VA), ventromedial (VM), and ventrolateral (VL) thalamic nuclei in the cat. The relative numbers of labeled neurons in the basal ganglia and the cerebellar nuclei were used to assess the extent to which the injection was in cerebellar-receiving or basal ganglia-receiving portions of thalamus. The rostral pole of VA showed reciprocal connections with prefrontal portions of the cerebral cortex. Only the basal ganglia and the hypothalamus provided non-thalamic input to modulate these cortico-thalamo-cortical loops. In VM, there were reciprocal connections with prefrontal, premotor, and insular areas of the cerebral cortex. The basal ganglia (especially the substantia nigra), and to a lesser extent, the posterior and ventral portions of the deep cerebellar nuclei, provided input to VM and may modulate these corticothalamo-cortical loops. The premotor cortical areas connected to VM include those associated with eye movements, and afferents from the superior colliculus, a region of documented importance in oculomotor control, also were labeled by injections into VM. The dorsolateral portion of the VA-VL complex primarily showed reciprocal connections with the medial premotor (area 6) cortex. Basal ganglia and cerebellar afferents both may modulate this cortico-thalamo-cortical loop, although they do not necessarily converge on the same thalamic neurons. The cerebellar input to dorsolateral VA-VL was from posterior and ventral portions of the cerebellar nuclei, and the major potential brainstem afferents to this region of thalamus were from the pretectum. Mid- and caudo-lateral portions of VL had reciprocal connections with primary motor cortex (area 4). The dorsal and anterior portions of the cerebellar nuclei had a dominant input to this corticothalamo-cortical loop. Potentially converging brainstem afferents to this portion of VL were from the pretectum, especially pretectal areas to which somatosensory afferents project.List of Abbreviations AC central amygdaloid nucleus - AL lateral amygdaloid nucleus - AM anteromedial thalamic nucleus - AV anteroventral thalamic nucleus - BC brachium conjunctivum - BIC brachium of the inferior colliculus - Cd caudate nucleus - CL centrolateral thalamic nucleus - CM centre median nucleus - CP cerebral peduncle - CUN cuneate nucleus - DBC decussation of the brachium conjunctivum - DR dorsal raphe nuclei - EC external cuneate nucleus - ENTO entopeduncular nucleus - FN fastigial nucleus - FX fornix - GP globus pallidus - GR gracile nucleus - IC internal capsule - ICP inferior cerebellar peduncle - IP interpeduncular nucleus - IVN inferior vestibular nucleus - LD lateral dorsal thalamic nucleus - LGN lateral geniculate nucleus - LH lateral hypothalamus - LP lateral posterior thalamic complex - LRN lateral reticular nucleus - LVN lateral vestibular nucleus - MB mammillary body - MD mediodorsal thalamic nucleus - MG medial geniculate nucleus - ML medial lemniscus - MLF medial lengitudinal fasciculus - MT mammillothalamic tract - MVN medial vestibular nucleus - NDBB nucleus of the diagonal band of Broca - NIA anterior nucleus interpositus - NIP posterior nucleus interpositus - OD optic decussation - OT optic tract - PAC paracentral thalamic nucleus - PPN pedunculopontine region - PRO gyrus proreus - PRT pretectal region - PT pyramidal tract - PTA anterior pretectal region - PTM medial pretectal region - PTO olivary pretectal nucleus - PTP poterior pretectal region - Pul pulvinar nucleus - Put putamen - RF reticular formation - RN red nucleus - Rt reticular complex of the thalamus - S solitary tract - SCi superior colliculus, intermediate gray - SN substantia nigra - ST subthalamic nucleus - VA ventroanterior thalamic nucleus - VB ventrobasal complex - VL ventrolateral thalamic nucleus - VM ventromedial thalamic nucleus - III oculomotor nucleus - IIIn oculomotor nerve - 5S spinal trigeminal nucleus - 5T spinal trigeminal tract - VII facial nucleus     

Organization of transient projections from the primary somatosensory cortex to the cerebellar nuclei in kittens

Summary The organization of transient projections from the primary somatosensory cortex (SI) to the cerebellar nuclei was studied in neonatal cats. Tritiated amino acids were injected into the face, forelimb, or hindlimb areas of SI in 4 to 6-day-old kittens. The animals were killed 3 to 6 days later and their brains processed for autoradiography. Labeled axons were found bilaterally in the cerebellar nuclei, but, although the distribution of label was similar on both sides, the label was always much denser on the side of the injection. Each area of SI demonstrated a characteristic pattern of projection to the cerebellar nuclei. Neurons in the hindlimb area projected to the rostral part of the anterior interpositus nucleus, the caudal part of the posterior interpositus nucleus, and the medial quadrant of the dentate nucleus. Fibers from the forelimb area were directed to the caudal part of the anterior interpositus and the rostral part of the posterior interpositus. Projections from the face area terminated principally in the caudal pole of the posterior interpositus. A small transitional area between the interpositus and fastigial nuclei was labeled with all injections. These data indicate that transient neocortical projections to the deep nuclei are organized and that the somatotopy of these projections is similar to that of other cerebellar nuclear connections.     

The distribution and origin of the ipsilateral descending limb of the brachium conjunctivum. An autoradiographic and horseradish peroxidase study in the rat

Summary The distribution, organization and origin of the ipsilateral descending limb of the Brachium Conjunctivum (B.C.), have been studied in the rat by using anterograde and retrograde tracing techniques. After injections of tritiated leucine/proline into the lateral cerebellar nucleus, covering both its medial part, corresponding to the dorsolateral hump (DLH) of Goodman et al. (1963) and its lateral part, (designated here as the lateral dentate, LD), and the neighboring interposed nucleus (NI), emerging fibres are numerous and leave laterally from the B.C. On the contrary, injections restricted to LD reveal very few such fibers. Within the lateral parvocellular reticular formation (LPRF) terminal labelling is heavy, and moderate to sparse within the adjacent trigeminal complex. Rostro-caudally, silver grain accumulation within the LPRF extends from the level of the motor trigeminal nucleus (VM) to the pyramidal decussation, exhibiting a cephalocaudal decrease of grain density. Within the trigeminal complex, labelling occurs in the caudal VM, the dorsal portion of the principal sensory nucleus, and within and around the trigeminal spinalis oralis. In addition, the area surrounding the VM (in part corresponding to the supratrigeminal region of Lorente de Nó 1922, 1933) is moderately labelled. After injections of HRP into various levels of the ipsilateral descending B.C.'s projection field, retrogradely labelled cells are numerous within the DLH. A slightly lesser amount of labelled cells are found in the lateral half of the NI, primarily concerning the nucleus interpositus posterior. Within the LD, only a few labelled cells are observed: these are mainly restricted to the dorsal portion at rostral levels of the nucleus. The results obtained by both the anterograde and retrograde studies suggest an absence of a topographic organization within this descending B.C. component. The possible functional meaning of these results is discussed.Abbreviations B.C. Brachium conjunctivum - DLH Dorsolateral hump - FTN Fibers of the trigeminal nerve - IO Inferior olive - LD Lateral dentate - LPRF Lateral parvocellular reticular formation - NI Interposed nucleus - NIA Nucleus interpositus anterior - NIP Nucleus interpositus posterior - NVII Facial nerve - PD Pyramidal decussation - TB Trapezoid body - VM Trigeminal motor nucleus - VPS Trigeminal principal sensory nucleus - VSC Trigeminal spinalis caudalis subnucleus - VSI Trigeminal spinalis interpolaris subnucleus - VSO Trigeminal spinalis oralis subnucleus - VII Facial nucleus - XII Hypoglossal nucleus This work was submitted as partial fulfillment for the degree of Doctorat de 3ème cycle at the Université Pierre et Marie Curie     

Brainstem origin of corticotropin-releasing factor afferents to the nucleus interpositus anterior of the cat

Corticotropin-releasing factor (CRF) has been described within varicosities that have a uniform distribution throughout the cerebellar nuclei of the cat. To date, however, no data are available as to the source of these nuclear afferents. Thus, a double-label technique was used to identify brainstem neurons which give rise to the CRF-containing afferents in the nucleus interpositus anterior (NIA) of the cat's cerebellum. Injections of fluorescent-tagged microspheres, which are retrogradely transported by cells with axons in the injection site, were made into lateral and medial aspects of the nucleus. The same sections were also processed for CRF immunohistochemistry. The primary source of CRF afferents to the NIA are the medial and dorsal accessory olivary nuclei. In addition to the inferior olive, several other brainstem nuclei also provide CRF afferents to the cerebellar nuclei. The medial aspect of the NIA receives afferents from the lateral reticular nucleus, external cuneate nucleus, perihypoglossal nucleus, medial vestibular nucleus and inferior central raphe nucleus. Additional afferents to more lateral aspects of the NIA are derived from the lateral reticular nucleus, external cuneate nucleus, and the magnocellular, lateral and gigantocellular tegmental areas. The brainstem nuclei that give rise to the CRF projection to the NIA receive input primarily from the spinal cord and likely relay information related to the status of an ongoing movement. A previous physiological study by Bishop has shown that CRF enhances the excitatory activity of nuclear neurons. CRF released from these afferents likely would enhance nuclear cell activity and thus provide a stronger or more prolonged effect on their respective target neurons in the brainstem.     

A cerebellar projection onto the pontine nuclei an experimental anatomical study in the cat

Summary Fibres passing from the intracerebellar nuclei to the pontine nuclei proper have been noted only by few students. In the present study this projection is analysed by mapping with the Nauta (1957) and Fink and Heimer (1967) methods the degeneration which occurs in the pontine nuclei following stereotactically placed electrolytic lesions in different parts of the intracerebellar nuclei in the cat. Cerebellopontine fibres come from the lateral cerebellar nucleus (NL) except its ventralmost part, and from the rostral but probably not from the caudal part of the interpositus anterior (NIA) and the interpositus posterior.The fibres end in three fairly well circumscribed regions of the pontine nuclei: a longitudinal column in the paramedian pontine nucleus, a column in the dorsolateral nucleus and one in the dorsal peduncular nucleus. Fibres from the NL as well as the NIA appear to end in all three regions, but the possibility of a more specific distribution cannot be excluded. Parts of the projection areas in the pons appear to be specific to cerebellar afferents, while other parts overlap with terminations of cerebropontine fibres, especially from SmI and SmII.The findings support the conclusions arrived at in recent studies of the cerebral corticopontine projections by P. Brodal (1968a, 1968b, 1971a, 1971 b) that the pontine nuclei are very precisely organized. The general principles in the organization of the corticopontine and cerebellopontine projections appear to be similar.Working in the Anatomical Institute, University of Oslo, with leave of absence from the Laboratory of Normal Anatomy, University of Coimbra, Portugal, with a grant from the Portugese Institute for Higher Culture.     

The cerebellar corticonuclear projection from lobule Vb/c of the cat anterior lobe: a combined electrophysiological and autoradiographic study

Summary The present study examines the projection to the cerebellar nuclei of Purkinje cells in particular sagittal zones within the intermediate region of the cerebellar cortex. The boundaries between the zones were delimited electrophysiologically on the basis of their climbing fibre input so that a small volume (10–120 nl) of ³H-leucine could be injected into the centre of a chosen zone. The subsequent uptake and orthograde transport of labelled material by the Purkinje cells was studied autoradiographically. It was found that the smallest injections resulted in injection sites restricted to a single cortical zone and extremely reproducible results could be obtained using such a combined electrophysiological/autoradiographic technique. Larger injections sometimes spread to a neighbouring zone but the resultant terminal labelling within the deep nuclei was invariably consistent with the results obtained from smaller injections. The c₁ and c₃ olivocerebellar zones, which are known to receive climbing fibre input transmitted from the ipsilateral forelimb via a dorsal funiculus spino-olivo-cerebellar pathway (DF-SOCP), were found to project to partially overlapping regions within nucleus interpositus anterior (NIA). No projection to nucleus interpositus posterior (NIP) was demonstrated for either zone. No distinction could be seen between the terminal fields for the medial and lateral halves of the c₁ zone which are, however, known to receive their climbing fibre input from quite separate regions within the inferior olive. The c₂ zone, which was delimited on the basis of its climbing fibre input which is transmitted from both forelimbs via a lateral funiculus SOCP, was found to project exclusively to interpositus posterior. The hemispheral d₁ zone was found to project to the transitional region where interpositus anterior and the dentate nucleus adjoin.