bluuebunny/crossref_metadata_2025_split huggingface dataset:
Projections of the visual cortex to the lateral geniculate and posterior thalamic nuclei in the cat
Authors: Niimi Kahee , Kawamura Syosuke , Ishimaru Shizuo 
Published: December 2004

AbstractFiber degeneration in the cat following lesions of various parts of areas 17, 18 and 19 was traced to the lateral geniculate and posterior thalamic nuclei by the method of Nauta and Gygax. Area 17 lying in the lateral and posterolateral gyri projects to the most medial parts of laminae A, A1 and central interlaminar nucleus (NIC). Area 17 in the suprasplenial gyrus sends fibers to the medial and middle parts of laminae A and A1 and the underlying part of NIC, while that in the splenial gyrus gives off fibers to the dorsolateral and ventrolateral parts of laminae A, A1 and NIC. These data indicate that there is a mediolateral organization in the projection from area 17 to the dorsal lateral geniculate nucleus. A topical organization exists also in the anteroposterior direction; the anterior, middle and posterior parts of area 17 project to the corresponding portion of the dorsal nucleus. Area 18 gives rise to fibers that pass between the medial interlaminar nucleus (NIM) and lamina A1 into the dorsolateral part of NIM, the medial part of NIC and the medial ends of laminae A and A1. The projections of area 18 to the dorsal nucleus are also organized in the anteroposterior dimension. Area 19 sends fibers to the major part of NIM, except to its most ventral and dorsolateral parts, and to the medialmost parts of NIC and lamina B. The majority of these fibers run along the medial aspect of NIM, but a few fibers pass ventrolaterally between NIM and lamina A1. It should be mentioned that NIM receives fibers not only from area 19 in the lateral and the posterior suprasylvian gyri, but also from area 19 in the medial cortex. As with areas 17 and 18, the corticogeniculate projections of area 19 are organized in an anteroposterior dimension.The ventral lateral geniculate nucleus also receives fibers from areas 17 and 19. The anterior part of area 17 projects only very few fibers to the ventral nucleus, but the posterior part gives off many fibers to the external layer of the nucleus. Area 17 fibers from the posterolateral gyrus are distributed in the dorso‐medial part of the external layer and those from the suprasplenial gyrus enter the ventral and medial portion of the layer. In contrast most of area 18 and that part of area 19 in the lateral gyrus project no fibers to the ventral nucleus. The other parts of area 19 give off fibers to the internal layer and the adjoining portion of the external layer of the ventral nucleus. There appears to be an anteroposterior organization of the projection of the visual cortex on the ventral nucleus. The posterior thalamic nucleus receives fibers from areas 18 and 19 and part of area 17. Area 18 sends fibers to the medial and ventromedial part of the posterior nucleus, while most of area 19 projects fibers to the dorsal and middle part of the nucleus. Area 17 lying in the upper portion of the posterolateral gyrus and the suprasplenial and splenial gyri projects to the dorsomedial and medial part of the posterior nucleus.
Studies on the developing cerebellum. II. The ultrastructure of the external granular layer
Authors: Del Cerro Manuel P. , Snider Ray S. 
Published: December 2004

AbstractThe ultrastructure of the external granular layer (EGL) of the rat cerebellum has been studied with special attention given to the changes occurring during its postnatal existence. Three periods are described: In the first period, lasting until day 5, the EGL is composed of a homogeneous population of germinal cells; the second period, lasting until day 17, is characterized by differentiation of neuroblasts which accumulate under the germinal cells forming the mantle zone. In the third period, the cell proliferation ends and the layer becomes progressively thinner and disappears by postnatal day 20. During these periods, the following cells have been identified: (A) germinal cells, ovoid or polyhedral and usually ciliated, have a comparatively large nucleus, a rim of cytoplasm, and an undetermined number of thin, long processes which persist during mitosis, although their fate during postmitotic differentiation was not established. (B) horizontal neuroblasts, with flattened nucleus and soma, are richer in organoids than the germinal cells, have neurotubules and thick lateral processes. (C) transitional bipolar neuroblasts resemble horizontal cells, except that most organoids, including the cilium migrate into the descending process. (D) A stage of apolar neuroblast has not been observed and there was no evidence of glial formation in the layer. A variety of cellular attachments are present, but synapses were not seen at any stage. At birth, the EGL adjacent to the pia mater is formed by EGL cells and their processes which are later replaced by the end feet of Bergmann glia which during a time exhibit giant mitochondria. Glial processes separate the EGL cells into columns and a neuropile is formed by these processes, and those of the EGL cells. The extension of the extracellular space is discussed as is the spontaneous degeneration of cells.
A stereotaxic atlas of the brainstem for Macaca mulatta in the sitting position
Authors: Smith Orville A. , Kastella Kenneth G. , Randall David C. 
Published: December 2004

AbstractAttempts to use existing stereotaxic atlases of the lower brainstem of monkeys for the placement of microelectrodes in the cranial nerve nuclei of awake animals have met with little success. The relationship of these nuclei to the bony structures used for orienting the head are probably altered when the position of the body is radically changed from the horizontal to the vertical (sitting) position. The atlas presented is based upon Macaca mulatta monkeys sitting in position in a primate restraint chair. This standard orientation provides a necessary frame of reference for accurate localization of lower brainstem structures.
Anatomical aspects of the superior olivary complex
Authors: Strominger Norman L. , Hurwitz Jessica L. 
Published: December 2004

AbstractThe cytology of the superior olivary complex was studied in Nissl stained sections of eight human brainstems, including adult, infant and fetus, and in the brains of ten juvenile rhesus monkeys. The most prominent components of the superior olivary complex of primates were specifically investigated, i.e., the medial (SOM) and lateral (SOL) superior olivary nuclei. Cell counts of these segments were done in human brainstems. The adult SOM was comprised of an average of 11,428 (7,850–15,010) perikarya; the SOL contained an average of 3,923 (2,890–5,400) neurons. These findings indicate that the SOL contains as many cells as reported in other primates, and is not reduced. The SOL appears somewhat inconspicuous in the human because it is organized into as many as six clusters of cells rather than forming one well circumscribed configuration as in the monkey and cat.The total cell population of the SOM together with the SOL was approximately the same on each side of individual brains. If one segment was larger on one side than the opposite side, the other segment was correspondingly reduced to maintain the relative symmetry. This suggests that a single mechanism controls the cell complement of at least these two segments of the superior olivary complex.
The developing caudate nucleus in the euthyroid and hypothyroid rat
Authors: Lu Elizabeth J. , Brown W. Jann 
Published: December 2004

AbstractThe basal ganglia are presently implicated in learning, and thyroid deficiency induced neonatally is known to affect mentation. The effects of such a deficiency on the developing caudate nucleus might be used to provide insight into structure and function of the normal subcortical brain, as well as possible influences of these extrapyramidal structures on mental retardation. Propylthiouracil was added to the diet of lactating rat dams and observations of the developing caudate nuclei of normal and hypothyroid rats were made at 8, 14, 20, 30 and 42 days by using various tissue stains and Golgi‐Cox preparations.Seven different types of neurons were distinguished in the caudate nucleus. Differences in the size of cell somata and the varying morphology of axons and dendrites were criteria used to make distinctions. Normally, the nucleus acquires cytoarchitectural complexity during the first three postnatal weeks. Within this period, neuron incidence increases in the caudate neuropil with age while the germinal matrix density decreases. Neuron accumulation reaches a plateau after the third week and cell migration is essentially complete at the end of the first postnatal month as shown by computer analysis of Nissl stained cell counts. Branching of cellular processes, attainment of receptor spines and complexity of the fiber network also appeared during this period.Retardation of structural development with thyroid hormone deficiency was shown by decreased numbers of neurons, inhibition of dendritic arborization, decreased numbers of dendritic spines and a reduced complexity of axonal plexuses. Thyroid deficiency delays cell migration during the first three weeks when compared to age‐matched normal controls. The lack of thyroid hormone does not appear to influence the size of neuron somata, and the extent of related dendritic fields, nor does hypothyroidism affect a specific cell type population. Generalized disturbances of caudate nuclear morphological maturation are caused by the deficiency. An apparent compensatory process, including a spurt of neural growth and differentiation, takes place in the period between days 14 and 30 in the deficient animals and a seemingly “normal” caudate cytoarchitecture is seen after the third postnatal week. Quantitative data, however, show that this rapid “catch up” process is inadequate.The developmental imperfection of the caudate nucleus which persists might be a part of the underlying substrate for the mental retardation, disturbed motor performance and perceptual handicaps which are found in the human patient.
A Golgi study on the habenular nucleus of the cat
Authors: Iwahori Nobuharu 
Published: December 2004

AbstractThe habenular nucleus of kittens was studied using the rapid Golgi and the Golgi‐Kopsch silver impregnation methods.The neurons of the medial habenular nucleus (MH) were classified into two types. The type I neurons, the main constituents of the MH, had piriform cell bodies with a mean diameter of 12 μm by 18 μm and two to five primary dendrites; dendrites had many spines. The type II neurons (14 μ 23 μm) were fusioform in shape and one to three primary dendrites arose from each pole of the cell bodies; dendrites had few spines. The axons of both types of neurons were traced into the fasciculus retroflexus Meynerti (FR), and intranuclear axon‐collaterals arose from axons of the type I neurons.The neurons of the lateral habenular nucleus (LH) were divided into four groups. Type I, II and III neurons were projection neurons of large, medium and small size, respectively. The type I neurons (27 × 43 μm) with four to seven primary dendrites were located mainly in the rostral and ventral areas of the LH. The type II neurons (15 × 33 μm) with two to four primary dendrites, the main constituents of the LH, were distributed throughout the LH. The type III neurons (15 × 25 μm) with two primary dendrites emerging from each pole of the soma were localized to the mediocaudal areas of the LH. The vast majority of axons of these projection neurons passed ventrally or ventrocaudally to enter the FR; only a few axons of these neurons were traced into the stria medullaris thalami (SM). The type IV neurons (12 × 25 μm) were small cells with short axons, suggesting the existence of a neural circuitry intrinsic to the LH. Bundle formation and glomerular arrangement of dendrites were observed in the medium‐sized LH neurons.The afferent fibers terminating within the MH coursed in the most medial part of the SM. These afferents were classified into medium‐caliber type I and fine type II fibers; both of these fibers emitted many intranuclear collaterals. There were also observed many fibers of passage which ran between the SM and FR, or between the habenular commissure (HC) and FR.The afferent fibers to the LH were divided into three groups; afferents via the HC, ascending and descending afferents. Most of the descending afferents entered the LH through the SM; some of them traversed the LH to join the FR or HC, or to extend to the pretectal region. The vast majority of the ascending afferents entered the LH via the FR; some of them extended rostrally to enter the SM. Some fibers in the HC also terminated within the LH. In addition to these afferents, many fibers of passage were seen to run through the LH and to bridge over between the SM and FR, or between the SM and HC.
The organization of the facial nucleus of the brush‐tailed possum (Trichosurus vulpecula)
Authors: Provis Jan 
Published: December 2004

AbstractThe facial nucleus of the brush‐tailed possum has been studied using Nissl staining and the horseradish peroxidase (HRP) retrograde tracing technique. In Nissl stained sections the nucleus is seen to comprise five distinct subnuclei. Injections of HRP into individual facial muscle groups have shown that these subnuclei reflect the peripheral innervation pattern of efferents from this nucleusAlthough in most cases, injection of HRP into a single facial muscle group resulted in the labelling of neurons in more than one facial subnucleus, the following subnuclei were most completely labelled subsequent to intramuscular injection of HRP: the dorsal intermediate subnucleus was labelled with HRP reaction product following injection of m. auricularis anterior; the middle intermediate subnucleus was labelled following injection of the muscle underlying the malar vibrissae; the ventral intermediate subnucleus was labelled following injection of the m. mentalis; the medial subnucleus was labelled following injection of the m. auricularis posterior; the lateral subnuleus was labelled following injection of the m. nasolabialis with HRPIn general there is a mediolateral representation in the facial nucleus of neurons innervating facial muscle groups which are found in anteroposterior succession along the head of the animal. Muscle groups found in dorsoventral succession on the animal are represented dorsoventrally in the facial nucleus.
Distinct auditory and lateral line nuclei in the midbrain of catfishes
Authors: Knudsen Eric I. 
Published: December 2004

AbstractThe catfish torus semicircularis (TS) comprises two major nuclei, which are specialized to process separately inputs of three acousticolateral modalities: VIII nerve acoustic input in one, and lateral line mechanoreceptive and electroreceptive input in the other. Electrophysiological recording and mapping experiments demonstrate a medial auditory region, a lateral electroreceptive region, and an intercalated mechanoreceptive region in the TS. Nissl and Golgi‐Cox preparations distinguish two rostrocaudally elongate, nuclear divisions, which correlate, one with the auditory and the other with the mechano‐ and electroreceptive regions.The medially positioned auditory nucleus is here called the nucleus centralis. The nucleus centralis appears as a rostrally flattened cylinder of uniformly packed cells, covered dorsally and laterally by a fiber rind. Cells within this nucleus conform to one of three general cell types based upon somatic and dendritic morphology: type 1 cells, which are the most abundant, have a single major primary dendrite and an axon typically arising from the same somatic pole; type 2 cells have two major primary dendrites and an axon, which issues from a third distinct somatic pole; and type 3 cells have several major primary dendrites and their axons are associated with one of the major somatic poles. No systematic orientation of dendrites could be found in the nucleus centralis.The laterally positioned lateral line nucleus, to be called the nucleus lateralis, includes two subdivisions: a large pars lateralis containing predominantly electroreceptive units, and a smaller, ventromedial pars medialis encompassing predominantly mechanoreceptive units. Each subdivision is found to be somatotopically organized, inputs from the head projecting to rostral areas and inputs from the tail to caudal areas. Although the cell types resemble those described for the nucleus centralis, a greater degree of cytoarchitectural orderliness is discernible: (a) cells in the nucleus lateralis group into four, alternating cell‐poor cell‐rich, layers; and (b) the dendritic fields of many type 1 and type 2 cells located in layer II tend to orient in a rostrodorsalcaudoventral attitude, perpendicular to the laminar planes.Fink‐Heimer preparations of brains with unilateral, lateral line lobe lesions demonstrate heavy fiber and terminal degeneration confined to the nucleus lateralis on both sides. Lateral line fibers ascend bilaterally in the lateral halves of the lateral lemnisci. At the level of the dorsal oculomotor nucleus the lemniscal fibers in this portion split into two fascicles, one proceeding rostrally to innervate the rostral portion of the nucleus lateralis, and the other arching back dorsolaterally to innervate the caudal portions of the nucleus.
The second somatic sensory area (smII) of opossum neocortex
Authors: Pubols Benjamin H. 
Published: December 2004

AbstractOrganization of the neocortical second somatic sensory area (SmII) of anesthetized Virginia opossums has been examined utilizing microelectrode recording techniques. SmII is situated between the first somatic sensory area (SmI) medially, and the rhinal fissure laterally. The head representation is located anteromedially within SmII, and the hindlimb representation posterolaterally, with the forelimb representation in between. Approximately 49% of SmII is devoted to representation of the head, 36% to forelimb representation, and 15% to trunk and hindlimb representation. All peripheral receptive fields (RF's) were either contralateral or bilateral. Approximately 63% of head RF's, 25% of forelimb RF's and 100% of hindlimb RF's were bilateral. For a given body locus, SmII RF's are larger than those for SmI. SmII is contained entirely within an area yielding evoked potentials responses to auditory click stimuli.
Visual discriminations of cats with cortical and tectal lesions
Authors: Loop Michael S. , Sherman S. Murray 
Published: December 2004

AbstractFourteen cats were trained on three visual discrimination tasks: light vs. dark, horizontal vs. vertical stripes, and upright vs. inverted triangles. Four of the cats then underwent large, bilateral occipito‐temporal cortex ablations; postoperatively, they demonstrated little or no visually guided orienting behavior and could solve only the brightness task and not the preoperatively learned pattern discriminations. Six other cats underwent the same cortical ablations plus a transection of the commissure of the superior colliculus; postoperatively, they demonstrated good visually guided orienting behavior (i.e., the Sprague effect) but still could solve only the brightness task. The final four cats were controls and underwent no surgery; they demonstrated good retention of the pattern task despite an extensive idle period corresponding to the postoperative period before retesting in the above ten cats. These data indicate that, while a transection of the collicular commissure after visual decortication dramatically improves visual orienting, it does not obviously improve visual discrimination abilities.
The lateral reticular nucleus of the opossum (Didelphis virginiana). II. Connections
Authors: Martin George F. , Andrezik J. , Crutcher K. , Linauts M. , Panneton M. 
Published: December 2004

AbstractConformational, histochemical and histofluorescent studies reveal that the entire lateral reticular nucleus (LRN) of the Virginia opossum is positive for cholinesterase activity and that its rostral portion is rich in fluorescent varicosities of the catecholamine type. Although neocortical‐LRN connections are relatively meagre, projections to the LRN from the red nucleus are extensive and topographically organized. Rubral‐LRN fibers arise from large‐medium sized neurons and distribute to the trigeminal division of the LRN as well as to specific portions of its external and internal divisions. Certain areas of the midbrain and pontine reticular formation, as well as the vestibular nuclei, project to the LRN and there is some evidence that reticular neurons adjacent to the LRN provide additional input. Although a relatively small fastigial‐LRN projection exists, no evidence was found for a contribution from any of the other deep cerebellar nuclei. Spinal‐LRN connections are extensive and topographically organized. Each of the inputs to the LRN have specific terminal targets, but there are varying degrees of overlap.Most of the LRN projects in an organized fashion to the anterior lobe of the spinal cerebellum, whereas only relatively restricted areas relay to the paramedian lobule and the pyramis. Lateral reticular axons distribute to specific longitudinal zones in such areas and the available material suggests that both convergence and divergence exist. The LRN also relays to the lobus simplex, and perhaps to crus I, as well as to visual‐auditory areas of the cerebellar vermis. The distribution of the various afferent connections of the LRN is interpreted in light of LRN‐cerebellar connections. Although we have described details that have not been elucidated in other species, where comparisons can be made it appears that the connectivity of the opossum LRN is comparable in most respects to that of placental mammals.
Retinal projections in the native cat, Dasyurus viverrinus
Authors: Sanderson K. J. , Pearson Lyn J. 
Published: December 2004

AbstractRetinal projections were examined in the native cat, Dasyurus viverrinus using Fink‐Heimer material and autoradiography. We found six regions in the brain which receive retinal projections. These are (1) the dorsal lateral geniculate nucleus (2) the ventral lateral geniculate nucleus (3) the lateral posterior nucleus (4) the pretectum (5) the superior colliculus, and (6) the accessory optic system. We did not examine the hypothalamus. The accessory optic system and the lateral posterior nucleus receive a contralateral retinal projection only and the other four regions receive a bilateral retinal projection.There is extensive binocular overlap in the dorsal lateral geniculate nucleus. On the side contralateral to an eye injection of 3H leucine our autoradiographs show four contralateral layers which fill most of the nucleus. Three of these layers, 3, 4 and 5, also receive input from the ipsilateral eye. Layer 1 which lies adjacent to the optic tract receives only contralateral retinal input. Layer 2 receives a direct retinal input only from the ipsilateral eye. The ipsilateral projection to the dorsal lateral geniculate nucleus forms a fairly continuous patch which is not divided into separate layers. The ipsilateral retinal input is located in the dorsal part of the lateral geniculate nucleus. The ventral quarter of the nucleus only receives a contralateral retinal input and therefore represents the monocular part of the visual field.