bluuebunny/crossref_metadata_2025_split huggingface dataset:
Descending pathways from the superior colliculus: An autoradiographic analysis in the rhesus monkey (Macaca mulatta)
Authors: Harting John K. 
Published: December 2004

AbstractThe autoradiographic tracing method has been used to identify the various descending tectofugal pathways and their targets in the rhesus monkey (Macaca mulatta).The present data reveal that the majority of descending tectofugal axons arise from collicular laminae which lie ventral to the stratum opticum (layer 3). Such descending axons can be grouped into two major bundles or tracts, i.e., the ipsilateral tectopontine‐tectobulbar tract and the crossed tectospinal tract (or the predorsal bundle). There is, in addition to these two major pathways, a smaller, commissural projection.The ipsilateral pathway courses laterally and ventrocaudally to terminate within the parabigeminal nucleus, the mesencephalic reticular formation, the dorsal lateral pontine gray (in several discrete patches), the dorsal lateral wing of the nucleus reticularis tegmenti pontis, and within the nucleus reticularis pontis oralis. Other ipsilateral targets of the deep tectal layers are the cuneiform nucleus and the external nucleus of the inferior colliculus. In several experiments transported protein is also apparent within the substantia nigra.Axons which comprise the tectospinal tract, or the predorsal bundle, cross within the dorsal tegmental decussation and descend within the brainstem in a position slightly lateral to the midline. The most rostral and quite extensive target of the predorsal bundle is the nucleus reticularis tegmenti pontis. As the predorsal bundle courses caudally within the pontine tegmentum, labeled axons enter the dorsal and medial regions of both the oral and the caudal divisions of the nucleus reticularis pontis. At caudal medullary levels, the majority of the labeled axons comprising the predorsal bundle pass ventrally to end quite profusely within the subnucleus b of the medial accessory nucleus of the inferior olivary complex. Caudal to this only a few scattered, labeled axons can be followed into the cervical spinal cord.Labeled axons also pass to the opposite, or contralateral colliculus via the tectal commissure. Such axons appear to arise and end primarily within the deeper tectal layers.In one experiment, the injection invaded the mesencephalic nucleus of the trigeminal nerve. Labeled axons were apparent within the motor nucleus, the chief sensory nucleus (quite profusely) and within the spinal or descending nucleus of the trigeminal nerve.
Connections of the pretectum in the cat
Authors: Berman Nancy 
Published: December 2004

AbstractThe connections of the pretectal complex in the cat have been examined by anatomical methods which utilize the anterograde axonal transport of tritiated proteins or the retrograde axonal transport of the enzyme horseradish peroxidase. Following injections of tritiated amino acids into the eye, label can be seen in the contralateral and ipsilateral nucleus of the optic tract and olivary nucleus where it appears as two or three finger‐like strips. Following large injections of tritiated amino acids into the pretectal complex transported label accumulates ipsilaterally in a region dorsolateral to the red nucleus, the central and pericentral divisions of the tegmental reticular nucleus, the intermediate layers of the superior colliculus, the nucleus of Darkschewitch, the thalamic reticular nucleus, zona incerta and fields of Forel, the central lateral nucleus, the pulvinar nucleus and the ventral lateral geniculate nucleus. Contralaterally label accumulates in the nucleus of the posterior commissure, the interstitial nucleus of Cajal, the anterior, posterior and medial pretectal nuclei, and the ventral lateral geniculate nucleusFrom smaller injections, more or less well confined to single nuclei, the following patterns of connections are demonstrated. The nucleus of the optic tract projects to the ipsilateral ventral lateral geniculate nucleus and pulvinar nucleus and to the contralateral nucleus of the posterior commissure. The anterior pretectal nucleus projects to the ipsilateral central lateral nucleus, the reticular nucleus, zona incerta, fields of Forel, the region dorsolateral to the red nucleus and to the contralateral anterior pretectal nucleus. The posterior pretectal nucleus seems to project only to the ipsilateral reticular nucleus and zona incerta. The central tegmental fields deep to the pretectum project to the tegmental reticular nucleus of the brainstem. When the injection involves the nucleus of the posterior commissure label is seen in the ipsilateral nucleus of Darkschewitch, and in the contralateral nucleus of the posterior commissure and interstitial nucleus of Cajal but no nucleus of the pretectum could be positively identified as projecting to any of the motor nuclei of cranial nerves III, IV, and VI.Following large injections of horseradish peroxidase into the pretectal complex, labeled cells are seen in the superficial layers of the ipsilateral superior colliculus, in the ipsilateral ventral lateral geniculate nucleus, reticular nucleus and zona incerta and in the contralateral anterior, medial and posterior pretectal nuclei, nucleus of the optic tract and ventral lateral geniculate nucleus.
The parasagittal zonation within the olivocerebellar projection. I. Climbing fiber distribution in the vermis of cat cerebellum
Authors: Groenewegen H. J. , Voogd J. 
Published: December 2004

AbstractAfter lesions of inferior olive, survival times of 5 to 12 days and Nauta staining, degeneration is present in white matter and central cerebellar nuclei and Deiters' nucleus. Shorter survival times from 40 to 60 hours and Fink‐Heimer impregnation reveal degenerating climbing fiber terminals in the molecular layer. With 3H‐leucine autoradiography and survival times of three to seven days the entire trajectory of the climbing fibers can be traced. Olivocerebellar fibers cross in the brain stem and terminate contralaterally in cortex and central nuclei. Occasional labeling of mossy fiber terminals is explained by involvement of reticular nuclei.Small parts of the inferior olive connect with narrow longitudinal zones in the cortex through compartments in the white matter. The corresponding distribution of olivocerebellar fibers and Purkinje cell axons over these compartments suggests that the organization of the olivocerebellar and corticonuclear projection is essentially similar. Collaterals always terminate in the central cerebellar necleus which receives a corticonuclear projection from the zone in which the parent fibers terminate.Caudal medial accessory olive projects to medial vermal zone A and to fastigial nucleus, subnucleus beta projecting to lobule VII and caudal fastigial nucleus. Cadual dorsal accessory olive projects to lateral vermal zone B in lobules I‐VI, Deiters' nucleus and dorsomedial subnucleus of interposed nucleus. The caudal principal olive (dorsal cap, ventrolateral outgrowth receiving visual and vestibular input) projects to flocculo‐nodular lobe.
Retinogeniculate projections in the rabbit: An autoradiographic study
Authors: Takahashi Ellen S. , Hickey Terry L. , Oyster Clyde W. 
Published: December 2004

AbstractAs shown by autoradiographic techniques, the pattern of retinogeniculate projections in the pigmented rabbit is generally similar to that described in preious studies. Each retina projects bilaterally to the α segment of the dorsal lateral geniculate nucleus (LGd) and to the external segment of the ventral lateral geniculate nucleus (LGv). The β segment of the LGd and internal layer of the LGv receive contralateral inputs only.The α segment of the LGd contains an irregularly shaped region which receives overlapping bilateral projections. Within this region the ipsilateral input is continuous and predominant. This pattern of ipsilateral projection can account for both the laminar arrangement perpendicular to the lines of projection and the “hidden lamination” which have been described previously for the rabbit LGd.A separate bilateral projection is identified for a group of cells lying between the LGd and LGv rostrally. Caudally this intergeniculate leaflet extends medial and ventral to the LGv and appears to merge with the zona incerta.
Synaptic Organization of the external cuneate nucleus in the rat
Authors: Rosenstein Jeffrey M. , Leure‐Dupree Alphonse E. 
Published: December 2004

AbstractThe normal synaptic organization of the rat external cuneate nucleus (ECN) has been investigated. The characteristic feature of the ECN neuropil is complex synaptic arrangements termed synaptic glomeruli. These involve both axo‐dendritic and axo‐axonic synapses and usually are isolated from the surrounding neuropil by lamellar glial sheaths. Glial isolation of synaptic glomeruli is conspicuous near capillaries. Central glomerular bouton profiles vary in size (2–9 μm diam) and configuration. They form asymmetrical synapses onto dendritic shafts and spines and occasionally receive symmetrical synapses from en passant bouton profiles.Other forms of axo‐dendritic synapses not associated with synaptic glomeruli are observed. The type frequently observed is formed by one or more boutons (0.5–4.0 μm diam) synapsing onto a dendrite or dendritic spine. “Isolated” axo‐dendritic synapses are surrounded by glial lamellae. Elongated “giant” boutons make multiple synaptic contacts along a dendritic shaft.Serial axo‐axonic synapses are found mainly in caudal regions of the nucleus. Axo‐somatic synapses are formed by small boutons (0.3–2.0 μm diam) contacting medium (16–24 μ) and small (9–14 μm) neurons. The least frequently observed bouton type in the rat ECN contains numerous granular vesicles, 80‐100 nm in diameter. These boutons may contact dendrites, neuronal somas or other boutons.
Three types of horizontal cells in the stingray retina: Their morphology and physiology
Authors: Toyoda Jun‐Ichi , Saito Takehiko , Kondo Hiroaki 
Published: December 2004

AbstractHistological and electrophysiological features of horizontal cells were studied in the stingray retina in which the ratio of rods to cones was about five to one. There were three distinct sublayers of horizontal cells; external, middle and internal. The type of horizontal cells recorded was identified by dye injection after recording. Relatively thick external horizontal cells sent their short dendrites into both rod and cone terminals to make synaptic contacts. The response recorded from them was not color‐coded but showed a Purkinje shift depending on the adaptational state. Middle horizontal cells were flat and usually two or three of them overlying each other constituted the middle sublayer. Their response, which was difficult to record in the light‐adapted retina, was characterized by a slow time course, a prolongation of the response to bright flashes and a maximum sensitivity in the green region of the spectrum without any sign of Purkinje shift. Internal horizontal cells were color‐coded. They responded with hyperpolarization at shorter wavelengths and with depolarization at longer wavelengths. It was concluded that the internal horizontal cells receive inputs from cones and the middle horizontal cells from rods, whereas the external horizontal cells receive inputs from both rods and cones.
An autoradiographic analysis of the differential ascending projections of the dorsal and median raphe nuclei in the rat
Authors: Azmitia Efrain C. , Segal Menahem 
Published: December 2004

AbstractThe differential projections from the dorsal raphe and median raphe nuclei of the midbrain were autoradiographically traced in the rat brain after 3H‐proline micro‐injections. Six ascending fiber tracts were identified, the dorsal raphe nucleus being the sole source of four tracts and sharing one with the median raphe nucleus. The tracts can be classified as those lying within the medial forebrain bundle (dorsal raphe forebrain tract and the median raphe forebrain tract) and those lying entirely outside (dorsal raphe arcuate tract, dorsal raphe periventricular tract, dorsal raphe cortical tract, and raphe medial tract). The dorsal raphe forebrain tract lies in the ventrolateral aspect of the medial forebrain bundle (MFB) and projects mainly to lateral forebrain areas (e.g., basal ganglion, amygdala, and the pyriform cortex). The median raphe forebrain tract lies in the ventromedial aspect of the MFB and projects to medial forebrain areas (e.g., cingulate cortex, medial septum, and hippocampus). The dorsal raphe cortical tract lies ventrolaterally to the medial longitudinal fasciculus and projects to the caudate‐putamen and the parieto‐temporal cortex. The dorsal raphe periventricular tract lies immediately below the midbrain aqueduct and projects rostrally to the periventricular region of the thalamus and hypothalamus. The dorsal raphe arcuate tract curves laterally from the dorsal raphe nucleus to reach the ventrolateral edge of the midbrain and projects to ventrolateral geniculate body nuclei and the hypothalamic suprachiasmatic nuclei. Finally, the raphe medial tract receives fibers from both the median and dorsal raphe nuclei and runs ventrally between the fasciculus retroflexus and projects to the interpeduncular nucleus and the midline mammillary body.Further studies were done to test whether the fiber tracts travelling in the MFB contained 5‐HT. Unilateral (left) injections of 5,7‐dihydroxytryptamine (5 μgm/400 nl) 18 days before midbrain raphe microinjections of 3H‐proline produced a reduction in the grain concentrations in all the ascending fibers within the MFB. Furthermore, pharmacological and behavioural evidence was obtained to show that the 5‐HT system had been unilaterally damaged; these animals displayed preferential ipsilateral turning in a rotameter which was strongly reversed to contralateral turning after 5‐hydroxytryptophan administration.The results show that DR and MR nuclei have numerous ascending projections whose axons contain the transmitter 5‐HT. The results agree with the neuroanatomical distribution of the 5‐HT system previously determined biochemically, histochemically, and neurophysiologically. The midbrain serotonin system seems to be organized by a series of fiber pathways. The fast transport rate in these fibers was found to be about 108 mm/day.
The morphological and physiological properties of a regenerating synapse in the C.N.S. of the leech
Authors: Muller Kenneth J. , Carbonetto Salvatore 
Published: December 2004

AbstractRegeneration of an electrical synapse between particular interneurons in the medical leech was traced physiologically and morphologically using intracellular recording and horseradish peroxidase (HRP) injection. The synapse between S‐cell interneurons lies in the connective midway between segmental ganglia, so crushing near one ganglion severs only one S‐cell's axon. The severed distal stump remains connected to the adjacent uninjured S‐cell and continues for weeks to conduct impulses. The injured cell regenerates, while its uninjured “target” neuron in the next ganglion does not grow. After the sprouts of the regenerating neuron cross the crush, one or a few branches grow along the surviving distal stump toward the original synapse. After about one month when the region of original synapse has been reached, regenerating neurons from electrical junctions and stop growing. Thereafter electrical coupling improves in stages. Within two months the regenerated neuron attains full caliber, the stump degenerates and function is normal. In some instances within days or weeks of crushing, the regenerating neuron forms a basket of synapses upon its severed distal stump and then continues growing to synapse with the target. When this occurs, electrical coupling and subsequent impulse transmission between S‐cells rapidly resumes. These experiments indicate that the regenerating neuron is guided to its proper synaptic target by recognizing and following its severed distal stump. Sometimes the distal stump itself becomes an intermediate synaptic target.
Rods and cones in the mouse retina. II. Autoradiographic analysis of cell generation using tritiated thymidine
Authors: Carter‐Dawson Louvenia D. , Lavail Matthew M. 
Published: December 2004

AbstractThe period of cell genesis of rod and cone photoreceptor cells has been determined in the retinas of C57BL/6J mice. Embryonic mice were exposed to a single dose of 3H‐thymidine at embryonic day (E) 10‐18 by injecting pregnant mice intraperitoneally. Animals at postnatal ages were injected subcutaneously once between postnatal day (P) 0‐10. The eyes were removed at one to three months of age. After fixation, they were embedded in glyol methacrylate, sectioned at 1.5 μm and prepared for autoradiographic analysis. All of the cone cells are generated over a relatively short time interval during the fetal period. In the posterior retina, the peak of cone cell genesis occurs at E13‐E14, and no cones are generated after E16. The rods, by contrast, are generated later and over a longer time period. They first begin to be generated in the posterior retina on E13, but the peak of cell genesis in not reached until the day of birth, and some rods are generated as late as P5. For both rods and cones the peaks of cell genesis in the peripheral retina occur two to three days later than in the posterior retina. The findings demonstrate that rods and cones are developmentally distinct cell types in the mouse retina.
Postnatal development of cholinergic neurotransmitter enzymes in the mouse cerebellum. Biochemical, light microscopic and electron microscopic cytochemical investigations
Authors: Olschowka John A. , Vijayan Vijaya K. 
Published: December 2004

AbstractThe activity and distribution of the cholinergic neurotransmitter enzymes acetylcholinesterase (AChE) and choline acetyltransferase (ChAc) in the developing cerebellum of the mouse were investigated using biochemical assays and light microscopic histochemistry for AChE and ChAc, and electron microscopic histochemistry for AChE.Postnatal alterations in the levels of AChE and ChAc in the cerebellum of the mouse are characterized by a divergent pattern. During the first two postnatal weeks, AChE activity increases progressively, whereas ChAc activity remains low. Beyond day 14, when AChE activity is steady or gradually decreasing, ChAc increases sharply to reach a peak on day 32. Histochemically, AChE activity is associated with the glomeruli and the Golgi cells of the internal granular layer, the medullary layer, and the deep cerebellar nuclei. Purkinje cells exhibit transient staining between days 2 and 9. At the ultrastructural level, AChE staining is first demonstrated on day 6 within the Golgi cell soma, on day 9 at the mossy fiber–granule cell synapse, and on day 11 at the Golgi terminal–granule cell synapse. The staining intensity of these structures reaches that of the adult on day 19.The histochemical reaction for ChAc is localized to moderate number of presumed Bergmann glial cells, a few large cells of the deep cerebellar nuclei, small numbers of Golgi cells, and all immature Purkinje cells. The molecular layer, glomeruli, and the medullary layer fail to demonstrate ChAc activity. This distribution of ChAc sharply contrasts with the localization established by other methods previously and is interpreted in the light of the drawbacks of the histochemical procedure.The biochemical fluctuations in AChE activity, correlated with the histochemical and cytochemical data, suggest that the postnatal increases in the enzyme are related to the ingrowth of the mossy fibers and to the maturation of the AChE‐positive Golgi cells. Histochemical evidence for the correlation between the ontogenetic increases in cerebellar ChAc activity and progressive mossy fiber innervation must await the application of the immunohistochemical method to the developing cerebellum.
Central gustatory paths in the crucian carp, carassius carassius
Authors: Morita Yasuhiro , Ito Hironobu , Masai Hideo 
Published: December 2004

AbstractThe central fiber connections of the gustatory system (VII, IX, and X nerves) in the crucian carp were examined by the Fink‐Heimer method and its modification.The sensory and recurrence roots of the VII enter the brainstem separately and terminate in the ipsilateral half of the facial lobe (L‐VII). Afferent fibers of the IX terminate in the glossopharyngeal lobe (L‐IX). Most afferent fibers of the X terminate in the sensory layer of the vagal lobe (L‐X), in which degenerating terminals occur in some laminae. Some vagal afferents project bilaterally to the commissural nucleus of Cajal. The cutaneous component of the X projects to the nucleus of the spinal trigeminal tract (SpV) and the medial funicular nucleus (nFM).Ascending secondary fibers from the L‐VII project bilaterally to the secondary gustatory nucleus (nGS) in the isthmus region. Descending secondary fibers from the L‐VII turn caudally in the SpV. These fibers terminate mostly in the nucleus of the SpV and sparsely in the nFM. The L‐IX and L‐X give rise to the long and short secondary paths. The long path projects as the ascending secondary tract to the ipsilateral nGS. The short path includes secondary fibers projecting to the motor layer of the L‐X and the medullary reticular formation.Tertiary gustatory fibers arising in the nGS project ipsilaterally to two diencephalic nuclei: the nucleus glomerulosus and the nucleus diffusus lobi inferioris.
Prenatal development of the human lateral geniculate nucleus
Authors: Hitchcock Peter F. , Hickey T. L. 
Published: December 2004

AbstractThe development of the human lateral geniculate nucleus has been studied on Nissl‐ and silver‐stained sections from 61 fetal human brains collected during normal autopsy procedures. The age of the fetuses, which ranged from 16 to 40 (newborn) weeks was determined by comparing crown‐to‐rump lengths and body weights to the values published by Streeter (′20).The development of the human lateral geniculate nucleus is remarkably similar to the described for the rhesus monkey (Rakic, ′77). As a result of the late growth of the pulvinar, the human lateral geniculate nucleus is displaced and rotated such that, at around week 24, the nucleus has come to lie along the ventrolateral border of the thalamus. The cellular laminae that characterize the adult nucleus are formed over a 3‐week period of time beginning around the 22nd week of gestation. More caudal parts of the nucleus laminate first. During this same period of time, the optic disc representation in laminae 4 and 6 is also formed.Throughout most of the development of the human lateral geniculate nucleus, individual rows of cells can be seen extending across the nucleus. Although such rows of cells are best seen before the nucleus laminates, in older laminated nuclei the rows of cells are oriented either perpendicular or oblique, but never parallel, to the plane of the laminae. Previous findings in both the monkey (Rakic, ′77) and human (Hickey and Guillery, ′79) suggest it is possible that these rows of cells can be used to define the lines of projection through the nucleus. Incoming optic tract fibers run along, rather than perpendicular to, these rows of cells.