bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoreceptor mosaic: Number and distribution of rods and cones in the rhesus monkey retina
Authors: Wikler Kenneth C. , Williams Robert W. , Rakic Pasko 
Published: January 2005

AbstractVideo‐enhanced differential interference contrast optics was used to determine the number and distribution of photoreceptors across the entire retinal surface of 9 eyes obtained from 7 adult rhesus monkeys. We found that the retina of this primate contains an average of 3,100,000 cones (±130,000) and 61,000,000 rods (±7,500,000). Variation among animals in the number of rods and cones cannot be accounted for by differences in sex, age, or retinal surface area, nor is there a correlation between the number of rods and cones (a retina with a high number of rods does not typically have a high number of cones).Cone density peaks at 141,000 cones/mm2 in the foveola and decreases about 100‐fold toward the periphery. Rod density in a central annulus around the fovea is 130,000/mm2 and decreases 6–8‐fold toward the periphery. In all 9 retinae, we found that an area 4–5 mm dorsal to the fovea had the highest rod density at 184,000 rods/mm2. The functional significance of this area, which we term the dorsal rod peak DRP), may be related to high sensitivity vision under scotopic conditions. Outside of the DRP, rod density is symmetrical around the major axes of the retina, whereas cone density is elevated in nasal retina. Among animals, both rods and cones display a 2‐fold individual difference in receptor density at any given eccentricity.Although rods and cones differ in absolute number, the location and magnitude of their peak densities, and their central to peripheral density gradients, the ratio of the density of rods to cones (15–30:1) is remarkably stable from 3 mm to 15 mm eccentricity. The relative consistency in the proportion of rods and cones in extrafoveal retina may be related to mechanisms of retinal development and functional interactions between scotopic and photopic systems.
Visual and electrosensory circuits of the diencephalon in mormyrids: An evolutionary perspective
Authors: Wullimann Mario F. , Glenn Northcutt R. 
Published: January 2005

AbstractMormyrids are one of two groups of teleost fishes known to have evolved electroreception, and the concomitant neuroanatomical changes have confounded the interpretation of many of their brain areas in a comparative context, e.g., the diencephalon, where different sensory systems are processed and relayed. Recently, cerebellar and retinal connections of the diencephalon in mormyrids were reported. The present study reports on the telencephalic and tectal connections, specifically in Gnathonemus petersii, as these data are critical for an accurate interpretation of diencephalic nuclei in teleosts. Injections of horseradish peroxidase into the telencephalon retrogradely labeled neurons ipsilaterally in various thalamic, preglomerular, and tuberal nuclei, the nucleus of the locus coeruleus (also contralaterally), the superior raphe, and portions of the nucleus lateralis valvulae. Telencephalic injections anterogradely labeled the dorsal preglomerular and the dorsal tegmental nuclei bilaterally.Injections into the optic tectum retrogradely labeled neurons bilaterally in the central zone of area dorsalis telencephali and ipsilaterally in the torus longitudinalis, various thalamic, pretectal, and tegmental nuclei, some nuclei in the torus semicircularis, the nucleus of the locus coeruleus, the nucleus isthmi and the superior reticular formation, basal cells in the ipsilateral valvula cerebelli, and eurydendroid cells in the contralateral lobe C4 of the corpus cerebelli. Weaker contralateral projections were also observed to arise from the ventromedial thalamus and various pretectal and tegmental nuclei, and from the locus coeruleus and superior reticular formation. Tectal injections anterogradely labeled various pretectal nuclei bilaterally, as well as ipsilaterally the dorsal preglomerular and dorsal posterior thalamic nuclei, some nuclei in the torus semicircularis, the dorsal tegmental nucleus, nucleus isthmi, and, again bilaterally, the superior reticular formation.A comparison of retinal, cerebellar, tectal, and telencephalic connections in Gnathonemus with those in nonelectrosensory teleosts reveals several points: (1 the visual area of the diencephalon is highly reduced in Gnathonemus, (2) the interconnections between the preglomerular area and telencephalon in Gnathonemus are unusually well developed compared to those in other teleosts, and (3) two of the three corpopetal diencephalic nuclei are homologues of the central and dorsal periventricular pretectum in other teleosts. The third is a subdivision of the preglomerular area, rather than an accessory optic or pretectal nucleus, and is related to electroreception. The preglomerulo‐cerebellar connections in Gnathonemus are therefore interpreted as uniquely derived characters for mormyrids.
Development of the lateral geniculate nucleus: Interactions between retinal afferent, cytoarchitectonic, and glial cell process lamination in ferrets and tree shrews
Authors: Hutchins James B. , Casagrande Vivien A. 
Published: January 2005

AbstractWe have studied the relationship of retinal afferents, glial cell processes, and neuronal cytoarchitectonics in the lateral geniculate nucleus (LGN) of two species: tree shrews (Tupaia belangeri) and ferrets (Mustela putoris). Both species are relatively immature at birth, allowing the development of these features to be studied in the perinatal period.Retinal afferents, visualized by intraocular injection of a wheat germ agglutinin/horseradish peroxidase conjugate (WGA‐HRP), are apparently the first elements of the developing LGN to exhibit a characteristic layered pattern in tree shrews and ferrets. Some radial glia still remain in the LGN of both species as the retinal afferents are in the process of segregating.Glial cell processes were visualized immunohistochemically with antibodies to glial fibrillary acidic protein (GFAP) or vimentin. In both the ferret and tree shrew, layering of glial cell processes is first seen as the overlap of retinal terminal fields diminishes. In the tree shrew LGN, these bands of dense glial cell staining are seen in apparent future cellular layers, whereas in the ferret, glial cell banding appears in interlaminar zones. If one or both eyes are removed at birth in tree shrews (before LGN cell layers are formed), the glial cell pattern seen 1 week later is in accord with the distribution of surviving nerve cells. The glial processes do not appear to invade regions left by degenerating retinal terminals or dying LGN cells.Several days after the appearance of layered glial cell processes (in the tree shrew) or at about the same time as glial layering (in the ferret), the first interlaminar spaces develop between neuronal cells, marking the beginning of cytoarchitectonic lamination, with its distinctive alternating cell‐rich and cell‐poor zones. Over the next several weeks, LGN neurons in both species continue to segregate into characteristic layers until the final, adult pattern of neuronal lamination is evident; as this process is completed, glial cell lamination disappears.These observations suggest that glial cells may be involved in establishing the neuronal layers that characterize the mature LGN of many species.
Occipital cortex in man: Organization of callosal connections, related myelo‐ and cytoarchitecture, and putative boundaries of functional visual areas
Authors: Clarke Stephanie , Miklossy Judit 
Published: January 2005

AbstractHuman area 17 is known to contain a single (the primary) visual area, whereas areas 18 and 19 are believed to contain multiple visual areas (defined as individual representations of the contralateral visual hemifield). This is known to be the case in monkeys, where several boundaries between visual areas are characterized by bands of callosal afferents and/or by changes in myeloarchitecture. We here describe the pattern of callosal afferents in (human) areas 17, 18, and 19 as well as their cortical architecture and we infer the position of some visual areas.Sections from occipital lobes of 6 human brains with unilateral occipital infarctions have been silver‐impregnated for degenerating axons, thereby revealing callosal afferents to the intact occipital cortex. Their tangential distribution is discontinuous, even in cases with large lesions. A band of callosal afferents straddles the area 17/18 boundary, whereas the remainder of area 17 and a 15–45 mm wide stripe of area 18 adjacent to the callosal band along the 17/18 border are free of them. Patches of callosal afferents alternate with callosal‐free regions more laterally in area 18 and in area 19. We conclude that, in man, a second visual area (analogue of V2) lies in area 18, horseshoe‐shaped around area 17, and includes the inner part of the acallosal stripe adjacent to the callosal band along the 17/18 boundary. The outer part of this acallosal stripe belongs to a third visual area, which may contain dorsally the analogue of V3 and ventrally that of VP. Thus the lower parts of the second and third visual areas lie on the lingual gyrus, whereas the analogue of the macaque's fourth visual area probably lies on the fusiform gyrus.Although the proposed subdivision of the occipital cortex relies largely on the pattern of callosal afferents, some putative human visual areas appear to have distinct architectonic features. The analogue of V2 is rather heavily myelinated and its layer III contains large pyramidal neurons. Its upper part is not well delimited laterally since adjacent “V3” has similar architecture. Its lower part, however, differs clearly from the adjacent “VP,” which is lightly myelinated and lacks the large pyramids in layer III. The cortex lateral to “VP” is heavily myelinated and contains fairly large pyramids in layers III and V. The myeloarchitecture of the lateral part of the occipital cortex is not uniform; a very heavily myelinated region stands out in the lateral part of area 19, near the occipito‐temporal junction. This region is likely to be the analogue of the macaque's area V5‐MT.
Catecholaminergic innervation of the hippocampus in the cynomolgus monkey
Authors: Samson Yves , Wu Justin J. , Friedman Allan H. , Davis James N. 
Published: January 2005

AbstractWe studied the immunocytochemical distribution of catecholaminergic fibers in the hippocampal formation from two cynomolgus monkeys by using phenylethanolamine‐N‐methyltransferase, dopamine‐beta‐hydroxylase, and tyrosine‐hydroxylase antibodies. There were no phenylethanolamine‐N‐methyltransferase immunoreactive fibers suggesting the lack of epinephrine containing fibers. In order to compare the distributions of tyrosine‐hydroxylase and dopamine‐beta‐hydroxylase immunoreactive fibers, we counted fibers in four hippocampal regions, the dentate gyrus, CA3, CA1, and the subiculum at three different rostrocaudal levels. The distributions of dopamine‐beta‐hydroxylase and tyrosine‐hydroxylase immunoreactive fibers were overlapping but clearly different, suggesting that the hippocampus receives both noradrenergic and dopaminergic inputs in primates. Dopamine‐beta‐hydroxylase‐immunoreactive fibers were present in moderate density and roughly evenly distributed throughout the hippocampus. Tyrosine‐hydroxylase immunoreactive fibers were found in high density in the dentate gyrus, in the stratum lacunosum‐moleculare, and in the molecular layer of the subiculum. There were only minor side‐side and rostrocaudal differences in the distribution of tyrosine‐hydroxylase and dopamine‐beta‐hydroxylase immunoreactive fibers. The identification of a putative dopaminergic projection to primate hippocampus, which is more dense and widely distributed than in the rodent, parallels similar increases in dopaminergic projections reported for primate cerebral neocortex.
Galanin immunoreactive neurons in the human hypothalamus: Colocalization with vasopressin‐containing neurons
Authors: Gai W. P. , Geffen L. B. , Blessing W. W. 
Published: January 2005

AbstractGalanin (GA) is a recently described neuropeptide that has been demonstrated to be widely distributed in the hypothalamus of experimental animals. So far there is no immunohistochemical description of GA in the human hypothalamus and, in particular, no studies of the colocalisation of this neuropeptide with other transmitter candidates in the human hypothalamus. We have now investigated this question immunohistochemically by using human brains fixed by vascular perfusion within 24 hours of death. Nerve cell bodies and fibers stained for GA were observed throughout the hypothalamus. Major populations of GA‐ir cell bodies were found in the suprachiasmatic, intermediate, supraoptic, para ventricular, arcuate, tuberomammillary, and supramammillary nuclei. Scattered positive neurons were found in the periventricular preoptic area, the posterior hypothalamic nucleus, the lateral hypothalamic area, and zona incerta. A few positive cells were located in the dorsomedial and ventromedial hypothalamic nuclei. The number of GA‐ir neurons estimated from three brains was 11,100 ± 2,400 for the intermediate nucleus, 57,800 ± 9,100 for the supraoptic nucleus and 47,400 ± 13,900 for the para ventricular nucleus. GA‐ir fibers were widely distributed in the hypothalamus. They were more dense in the periventricular and medial hypothalamic zones, whereas the lateral tuberal nuclei and the dorsolateral part of the supraoptic nucleus contained sparse positive fibers. The mammillary complex contained almost no GA‐ir fibers. In the ventromedial tuberal region, GA‐ir axons formed bundles travelling down in the infundibular stem. In the median eminence the vascular plexus was wrapped by GA‐ir fiber networks.The coexistence of GA with arginine vasopressin (AVP), oxytocin (OXY), and tyrosine hydroxylase (TH) was examined in the supraoptic, paraventricular, and suprachiasmatic nuclei in adjacent paraffin sections. Neurons containing both GA and AVP were very common in the supraoptic nucleus and also occurred in the paraventricular and suprachiasmatic nuclei. The supraoptic and paraventricular nuclei also contained some neurons immunoreactive for both GA and OXY. Neurons positive for GA and TH were rare.The topographic distribution of GA‐ir neuronal structures in the hypothalamus and the colocalization of GA, principally with AVP and to a lesser extent with OXY, in some hypothalamic nuclei constitute anatomical evidence that this neuropeptide may be involved in the regulation of endocrine, autonomic, and behavioural homeostatic responses.
The projection from different visual cortical areas to the rat superior colliculus
Authors: Harvey Alan R. , Worthington Delys R. 
Published: January 2005

AbstractThe rat occipital cortex contains a number of morphologically and physiologically distinct visual areas. Retrograde tracing studies have shown that most if not all of these areas project in a topographic fashion to the ipsilateral superior colliculus (SC). In the present study, small amounts of wheat germ agglutinin‐conjugated HRP (WGA‐HRP) were injected into adult rat occipital cortex to determine how afferents from the different visual cortical areas are distributed within the various layers of the SC. Cytoarchitectonic criteria were used to help establish the location of the WGA‐HRP injections in the cortex. As a further aid to identifying the sites of injection, the distribution of retrogradely labelled cells within the thalamus was mapped in each brain.Analysis revealed a surprising range of visuocortical projections to the rat SC, with input to the majority of tectal laminae. Area 17 projected most heavily to the dorsal stratum opticum (SO) and lower half of stratum griseum superficial (SGS) with lighter label extending up to the collicular surface, Axons and terminals from area 18 formed two horizontal tiers, one in the middle of the stratum griseum intermediale (SGI) and the other at the border between the stratum album intermediale (SAI) and the stratum griseum profundum (SGP). Periodic puffs of label extended between these horizontal tiers, with a periodicity of 300–400 μm. There was some variability in the labelling pattern in the superior colliculus after area 18a injections, perhaps because this cytoarchitectonic area contains multiple representations of the visual field. Generally the projection from the lateromedial, laterointermediate, and laterolateral parts of 18a was heaviest in the lower half of SO and upper regions of SGI. Lighter label extended up into the lower half of SGS. In the SGI it was common to find periodic puffs of terminal label interspersed with areas devoid of innervation. This periodic pattern was particularly noticeable after WGA‐HRP injections into anterior 18a. Two horizontal tiers of label were located at the SO/SGI border and SGI/SAI border (the dorsal being the most dense) with patches of label extending between these tiers every 230–250 μm. There did not appear to be a significant corticotectal projection from the posterior part of the lateral extrastriate region.
Thalamic projections to sensorimotor cortex in the newborn macaque
Authors: Darian‐Smith Corinna , Darian‐Smith Ian , Cheema Surindar S. 
Published: January 2005

AbstractIn the present experiments thalamocortical projections to different functional areas of the newborn (or prematurely delivered) macaque's sensorimotor cortex were labeled using retrogradely transported fluorescent dyes. Several dyes were used in each animal to (1) enable the direct comparison of the soma distributions of different thalamocortical projections within thalamic space, and (2) identify by double labeling neurons shared between these distributions. The projection patterns in the newborn macaque were compared with those of the mature animal reported by Darian‐Smith et al. (J. Comp. Neurol. 1990;298:000–000).The main observations were (1) all thalamocortical projections to the sensorimotor cortex of the mature macaque are well established by embryonic days 146–150, as was shown by labeling these pathways in infants delivered by cesarian section, (2) a significant number of thalamocortical neurons in the newborn were double‐labeled following dye injections into different pre‐ or postcentral areas, and where the margins of the dye uptake zones were separated by 3–8 mm, and (3) extensive projections from the anterior pulvinar nucleus to the motor and premotor cortex, and to the supplementary motor cortex were labeled in the newborn macaque. Both the exuberant terminal arborizations, and the precentral pulvinar projections were diminished by the 6th postnatal month, and absent in the mature macaque. The role of epigenetic determinants of these postnatal events is briefly considered.
Lateral magnocellular thalamic nucleus in rabbits: Architecture and projections to cingulate cortex
Authors: Vogt Brent A. , Sikes Robert W. 
Published: January 2005

AbstractThe lateral magnocellular nucleus (LM) contains the largest neurons in the rabbit thalamus, yet its cortical connections have not been described. This study evaluates the architecture, cingulate cortical connections, and spontaneous rate of neuronal discharges in LM. At its maximal mediolateral extent in coronal sections, LM underlies the laterodorsal and lateroposterior nuclei. It has a short medial and long lateral limb, both of which have high levels of cytochrome oxidase activity. On the basis of horseradish peroxidase and fluorescent dye injections, LM projects primarily to area 29 and posterior area 24. Projections to area 29d are topographically organized so that the medial limb of LM projects to rostral area 29d, mid levels of LM where the limbs join project to midlevels of area 29d and lateral parts of the lateral limb project to posterior area 29d. It is mainly the midportion of the lateral and medial limbs that projects to areas 29b and 29c. The anterior parts of these areas receive input from dorsal parts of LM, whereas posterior levels of these areas receive input from ventral LM. The midregion of LM also projects to caudal area 24. Injections of 3H‐amino acids into area 29d anterogradely label neuronal processes in LM. Finally, single unit electrophysiological recordings from LM in halothane‐anesthetized rabbits showed a unique pattern of spontaneous discharges. Over 70% of the LM neurons cycled through a number of different phases with a mean ± S.E.M. peak discharge rate of 31 ± 4.7 Hz. This high rate contrasts with the 17.6 ± 3.2 Hz rate for neurons that maintained a constant rate of discharge and the 7.5 ± 1.3 Hz rate of discharges for neurons in nuclei dorsal and ventral to LM.LM neurons are large, have high levels of cytochrome oxidase and spontaneous activity, and project extensively to the posterior cingulate cortex. These features suggest that LM neurons are highly active metabolically and may be fast conducting efferents to cingulate cortex.
Three‐dimensional structural organization of layer I of the human cerebral cortex: A golgi study
Authors: Marín‐Padilla Miguel 
Published: January 2005

AbstractThe three‐dimensional structural organization of layer I of the developing and adult human cerebral cortex has been investigated by using sagittal, transverse, and tangential rapid Golgi and Klüver‐Barrera preparations. The actual morphology of its fundamental neuron—the Cajal‐Retzius cell (C‐R)—is established. These large and solitary cells are horizontal multipolar neurons characterized by: (1) long horizontal dendrites that radiate in all directions within a tangential plane parallel to the pial surface, (2) long horizontal axonic collaterals that radiate in all directions within layer I middle level, and (3) a descending axonic process that reaches the lower level, becomes a long tangential fiber—and eventually a myelinated one—and projects in any direction within this level. In cortical ontogenesis, its dendrites, axonic collaterals and terminal axon undergo a progressive multipolar “horizontalization” extending throughout the surface of the expanding cerebral cortex. The neuron's body and main dendrites will be found only in some areas, whereas its axonic collaterals and terminal tangential axon should be found throughout the cerebral cortex. This developmental feature explains the presence of two—middle and lower—plexuses in layer I, composed of the axonic collaterals and the terminal tangential axons of C‐R cells, respectively. It is emphasized that the basic morphology of the C‐R cell remains essentially unchanged in the course of cortical ontogenesis and that the neuron persists in the adult cerebral cortex. Whereas the C‐R cell is the basic neuron of layer I, the pyramidal cells dendritic bouquets represent its larger and main receptive surface (the only one early in development). By the 30th week of gestation, a C‐R cell could establish: (1) proximal contacts, through its axonic collaterals, with all dendritic bouquets within a ∼ 350 μm radius, and (2) distant contacts, through its tangential axon, with dendritic bouquets within a narrow sagittal, transverse, or diagonal territory several mm long. In cortical ontogenesis, the C‐R cells' functional territories continue to expand throughout the surface of the cerebral cortex and possibly overlap with each other, It is proposed that the C‐R cell receives inputs from primitive (mesencephalic?) corticipetal fibers and that it transmits the same kind of information (perhaps a basal tone?) to the dendritic bouquets of all pyramidal neurons throughout the cerebral cortex regardless of their location, cortical depth, or functional role.