bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efferent connections of the caudate nucleus, including cortical projections of the striatum and other basal ganglia: An autoradiographic and horseradish peroxidase investigation in the cat
Authors: Royce G. James , Laine Erick J. 
Published: January 2005

AbstractTritiated tracer was injected into the head of the caudate nucleus in cats. Following such injections, labeling is present within extensive regions of both the globus pallidus and entopeduncular nucleus, where it presents a mottled or meshlike appearance. These projections are topographically organized in that there is simple correspondence between the mediolateral, dorsoventral, and rostrocaudal origin of the caudate projection and its input to the globus pallidus and entopeduncular nucleus. Transported tracer is also present within the substantia nigra, where it is most abundant within the pars reticularis. However, distinct labeling also overlies cells of the pars compacta, and lesser amounts of labeling are present within the pars lateralis and within the retrorubral area.Following injections of horseradish peroxidase into the caudate nucleus, and subsequent tissue processing by the tetramethylbenzidine (TMB) method of Mesulam ('78), labeled anterograde fibers are present in abundance within the globus pallidus, entopeduncular nucleus, and all subdivisions of the substantia nigra, thus confirming the autoradiographic findings. Also, it is especially obvious in this HRP material that, contrary to previous degeneration studies, both the rostromedial and caudolateral parts of the pars lateralis of the substantia nigra contain numerous anterogradely labeled fibers. Retrogradely labeled neurons are also present within the substantia nigra of these same tissue sections, where they are most abundant within the pars compacta, but lesser numbers of labeled neurons are also present within the pars reticularis, pars lateralis, retrorubral area, and ventral tegmental area on the ipsilateral side, and all of these same subdivisions of the substantia nigra on the contralateral side. Also, within the subthalamic nucleus in these experiments, there are anterogradely labeled fibers, as well as retrogradely labeled neurons, which are interpreted to represent a reciprocal connection between the subthalamic nucleus and the striatum.In a separate series of experiments, horseradish peroxidase was injected into the motor cortex‐specifically into the anterior sigmoidal gyrus. Following such injections, labeled neurons representing afferents to the motor cortex are found in all subcortical nuclei commonly known as the “basal ganglia,” including the caudate nucleus, putamen, globus pallidus, entopeduncular nucleus, substantia innominata, nucleus of the diagonal band of Broca, medial septal nucleus, claustrum, and basolateral amygdaloid nucleus.
Direct connections of rat visual cortex with sensory, motor, and association cortices
Authors: Miller Michael W. , Vogt Brent A. 
Published: January 2005

AbstractEach division of rat visual cortex, areas 17, 18a, and 18b, has connections with sensory, motor, and association cortices. These corticocortical connections were sampled using anterograde autoradiographic and retrograde horseradish peroxidase labeling techniques.Area 17 is connected via reciprocal pathways with each division of visual cortex, the posterior one‐third of motor area 8, association area 7, and posteroventral area 36 of temporal cortex. It also receives projections from perirhinal areas 13 and 35.Area 18a has reciprocal connections with areas 17 and 18b, a patch in posterior somatosensory area 3, and dorsal auditory area 41. Like area 17, area 18a receives afferents from and projects to the posterior one‐third of motor area 8. The connections of area 18a with association cortices are extensive; these regions include parietal areas 7, 39, 40, and 14, posteroventral and dorsal area 36, and perirhinal cortex.Area 18b is connected with areas 17 and 18a, a patch in medial area 3, and dorsal area 41. There are reciprocal projections between area 18b and posterior area 8. As for association cortex, area 18b projects to frontal area 11, area 7, posteroventral and dorsal area 36, and perirhinal cortex. In addition, area 18b receives input from and projects efferents to the dorsal claustrum.Most of the interconnections among areas 17, 18a, and 18b originate from neurons in layers II, III, and V and end in terminal fields in layers I–III and V. In contrast, projections of other sensory, motor, and association cortices to visual cortex originate mainly from neurons in layer V and to a lesser extent from layer II. The reciprocal pathways from visual cortex terminate predominantly in the supragranular layers. In conclusion, these corticocortical pathways provide the basis for cortical visuosensory and visuomotor integration that may aid the rat in the coordination of visually guided behaviors.
Dendritic and axonal organization of mitral and tufted cells in the rat olfactory bulb
Authors: Orona Edward , Rainer Elizabeth C. , Scott John W. 
Published: January 2005

AbstractThe output cells of the main olfactory bulb, the mitral and tufted cells, can be categorized into subclasses on the basis of their intrabulbar dendritic and axonal characteristics. Their form was studied in rats following labeling by iontophoretic injection of horseradish peroxidase into the external plexiform layer (EPL). The fact that these extracellular injections labeled small numbers of neurons permitted reconstruction of individual cells. The injection depth within the EPL determined the type of cells labeled. Secondary dendrites of each cell type lay in one of three partially overlapping zones in the EPL. The deepest zone contained the secondary dendrites of one group of mitral cells (Type I), which had the deepest and longest dendrites of the output cells. An intermediate zone of the EPL contained the secondary dendrites of middle tufted and a second class of mitral cells (Type II). The superficial zone, adjacent to the glomerular layer, contained the relatively short, asymmetric dendritic fields of external tufted cells. The few labeled internal tufted cells had secondary dendrites in either the intermediate or deep zones. Every cell type, except the Type I mitral cells, had axon collaterals in the internal plexiform and upper granule cell layers. No cell types had axons re‐entering the EPL. These results for output cells combined with our previous observations on granule cells point to a functional sublaminar organization of the EPL that has not previously been proposed.
Organization of the cat's optic tract as assessed by single‐axon recordings
Authors: Mastronarde David N. 
Published: January 2005

AbstractThe organization of the cat's optic tract was assessed from recordings of single axons during vertical electrode penetrations. To analyse both the order and the scatter of axons in the optic tract, units were pooled from electrode tracks that had evidently passed through nearly equivalent parts of the tract. Receptive field elevation, the most strongly ordered parameter, was primarily organized horizontally, increasing from posteromedial to anterolateral tract. Azimuth tended to increase from dorsal to ventral, but was only half as well organized vertically as elevation was horizontally. Axon type was also organized vertically, at least among axons that were identified as X or Y (contralateral axons of less than 20° eccentricity). Axons of ON‐center X‐type were located mostly in the dorsal quarter, OFF‐center X‐type in the dorsal two‐thirds, and Y‐type (ON‐ and OFF‐center) in the ventral two‐thirds of the tract. Another difference between the horizontal and vertical axes was revealed by estimates that axons of one type, from one retinal locus, spread about twice as far vertically as horizontally in the tract.Torrealba et al. (1982) have proposed that the sequential addition of ingrowing axons to the pial surface is a major source of the order in the tract. The differences between horizontal and vertical order seen here suggest an extension of this proposal: the sequential addition of axons to the ventral surface generates the vertical order, while some other process arranges axons horizontally, along the ventral surface, according to receptive field elevation (or some similar one‐dimensional retinal coordinate).
Topographic organization of connections between the main olfactory bulb and pars externa of the anterior olfactory nucleus in the hamster
Authors: Schoenfeld Thomas A. , Macrides Foteos 
Published: January 2005

AbstractThe organization of connections between the main olfactory bulb (MOB) and pars externa (pE) of the anterior olfactory nucleus was studied in hamsters by using wheat germ agglutinin‐horseradish peroxidase as both an anterograde and a retrograde neuronal tracer. Bulbar efferents of pE project exclusively to the contralateral MOB. A topographic organization is evident in these efferents, such that distinct sectors of pE project predominantly to certain sectors of the contralateral MOB and lightly to other sectors. The predominant projection to any bulbar sector in the coronal plane is repeated at nearly all rostral‐caudal levels, i.e., the pE efferents to the contralateral MOB terminate within long strips or wedges that show a sector‐to‐sector topographic organization with respect to the medial‐lateral and dorsal‐ventral axes but not the rostral‐caudal axis of the MOB. Afferents to pE arising in the ipsilateral MOB also show a sector‐to‐sector topographic organization. Injections into restricted sectors along the circumference of pE label all classes of output neurons (mitral cells and internal, middle, and external tufted cells) in restricted sectors of the ipsilateral MOB, and the sectors that have retrograde neuronal labeling are homotopic to those in the contralateral MOB that have dense anterograde terminal labeling. External tufted cells are not labeled and the other classes of MOB output neurons do not have prominent topographic patterns of labeling in cases with injections caudal to pE. The somata of external tufted cells that project to pE are predominantly in the deep part of the glomerular layer; most of the external tufted cells that He more superficially in the glomerular layer do not appear to have projections extrinsic to the MOB. These results indicate that both the afferent and efferent connections of pE with the MOB are topographically organized and provide a short synaptic pathway between homotopic sectors of the two main olfactory bulbs.
The effects of a lengthy period of environmental diversity on well‐fed and previously undernourished rats. I. Neurons and glial cells
Authors: Bhide P. G. , Bedi K. S. 
Published: January 2005

AbstractMale rats undernourished from the 16th day of gestation until 25 postnatal days of age were raised either in enriched (EC) or isolated (IC) environmental conditions between about 35 and 115 days of age. A parallel set of well‐fed rats was raised in identical environments. At the end of this period all rats were killed by perfusion with 2% phosphate buffered glutaraldehyde.Body and forebrain weights and forebrain lengths and widths were determined for each animal. The left cerebral hemisphere was embedded in paraffin‐wax and serially sectioned. Three of these coronal sections (defined by subcortical landmarks) taken from the occipital cortex region were used for cortical depth measurements.Small pieces of cortical tissue taken from area 17 of the right cerebral hemisphere were embedded in resin and cut to yield 0.5 μm thick sections through the entire depth of the cortex. These sections were used to estimate the nuclear diameters and numerical densities of neurons and oligodendrocytes as well as neuronal perikaryal volumes.Two‐way analysis of variance tests on data combined from both nutritional groups revealed significant main effects of nutrition on body weight, forebrain weight, forebrain width, and forebrain length × width values. Environment had significant main effects on forebrain weight, forebrain length, forebrain length × width values, and on neuronal numerical density. The interaction between nutrition and environment was not significant for any of the measurements carried out. These results suggest that 80 days of environmental diversity beginning at about 35 days of age can produce morphological changes in the brains of both well‐fed rats and rats undernourished during early life. These changes seem to be similar in direction and magnitude in the two nutritional groups.
Cerebellar cortical efferent fibers in the North American opossum, Didelphis virginiana. II. The posterior vermis
Authors: Klinkhachorn P. S. , Haines D. E. , Culberson J. L. 
Published: January 2005

AbstractThe projection pattern of corticonuclear and corticovestibular fibers from vermis lobules VI–X of the North American opossum, Didelphis virginiana, was studied using a modification of the Fink and Heimer (1967) technique.The evidence suggests that corticovestibular projections in opossum are ipsilateral and exit the cerebellum via the juxtarestiform body. Lobules VI and VII contribute few, if any, corticovestibular projections. Corticovestibular fibers from lobule VIII are sparse to moderate and those from lobules IX and X are numerous. The main targets of corticovestibular fibers are the superior and spinal vestibular nuclei with some input to the medial vestibular nucleus, particularly from lobules IX and X. Although degenerated axons course through the lateral vestibular nucleus, they do not appear to terminate therein.Corticonuclear fibers from lobules VI–X are ipsilateral and terminate in the caudal and caudoventral one‐third of the medial cerebellar nucleus (NM). Fibers from lateral areas of some vermal lobules appear to enter contiguous parts of the immediately adjacent posterior interposed nucleus. Although each lobule projects into a specific area of caudal and caudoventral NM when the terminal fields for lobules VI–X are superimposed, it is apparent that they are largely coextensive. This is in contrast to the pattern seen in projections from the anterior vermis. The results further indicate that zones A and B are present in lobules VI–X of opossum.
Localizing spinal‐cord‐projecting neurons in neonatal and immature albino rats
Authors: Leong Seng Kee , Shieh Jeng Yung , Wong Wai Chow 
Published: January 2005

AbstractAccording to results from the horseradish peroxidase (HRP) method of tracing neuronal connections, the spinal cords of neonatal and immature rats receive a large number of descending projections from the first cervical cord segment, various brain‐stem nuclei, and deep cerebellar and diencephalic nuclei. All these projections are present at birth, though at this age some of them are not fully established. Thus, only a few cells in the trigeminospinal, solitariospinal, tectospinal, and cerebellospinal groups were labeled after HRP injection in the lumbosacral or cervical cord segments in neonatal animals. They were clearly labeled in older, immature animals. The labeled neurons in other descending pathways appeared to be equal in density in neonatal, immature, and adult rats. This visual impression was stregthened by the counts of neurons in the interstitial nucleus of Cajal, which showed no significant difference in the number of labeled neurons in the three age groups. However, counts of labeled cells in the lateral vestibular nucleus and nucleus of the posterior commissure showed that there is a steady rise in the number of labeled neurons as the animals increase in age.
Central projections from cat suboccipital muscles: A study using transganglionic transport of horseradish peroxidase
Authors: Bakker D. A. , Richmond F. J. R. , Abrahams V. C. 
Published: January 2005

AbstractCentral projections of suboccipital muscle nerves were examined following exposure of cut peripheral nerves to the tracer horseradish peroxidase. Labelled fibers entered the Cl and C2 dorsal roots and accumulated in the dorsolateral part of the dorsal funiculus. Many labelled fibers entered the grey matter of Cl to C3 in ventrally directed bundles which passed medially to the base of the dorsal horn. No terminal labelling was apparent in superficial layers of the dorsal horn. However, labelled fibers ramified extensively throughout, medial parts of the intermediate laminae, in and around the central cervical nucleus. Labelled fibers also projected toward the ventral horn. In cats subjected to ventral root section at the time of peripheral nerve exposure, a modest distribution of reaction product was observed deep in the ventral horn. In cats which did not undergo ventral root section, anterograde projections in the ventral horn were obscured by the simultaneous retrograde filling of motoneurons both in the ventromedial nucleus and on the medial and lateral borders of the gray matter. Labelled axons also coursed rostrally into the medulla where they formed a circumscribed bundle between the main cuneate nucleus and the spinal nucleus of V. Three consistent regions of HRP deposition could be identified at medullary levels. Dense accumulations of reaction product were present in circumscribed regions of the external cuneate nucleus (ECN) throughout its rostrocaudal extent. A second zone of dense labelling occurred in the intermediate nucleus of Cajal, where it appeared to form a continuing column rostral to the central cervical nucleus in C1–C3. Sparse labelling was restricted to a third zone in the ventrolateral part of the main cuaeate nucleus.
2‐deoxyglucose labelling of the infrared sensory system in the rattlesnake, Crotalus viridis
Authors: Gruberg Edward R. , Newman Eric A. , Hartline Peter H. 
Published: January 2005

AbstractInfrared (IR) responsive nuclei in the rattlesnake Crotalus viridis were identified by using 14C‐2‐deoxyglucose (2DG) and autoradiography. Following 2DG intracardial injection, the IR‐sensitive pit organ was stimulated periodically with an IR stimulus for 5 hours. The nucleus of the lateral descending trigeminal tract (LTTD, the primary IR sensory nucleus) was labelled heavily with 2DG. Labelling was bilateral, but somewhat heavier ipsilateral to the stimulated pit organ. The nucleus reticularis caloris (RC, the secondary nucleus of the IR system) was lightly labelled ipsilaterally. The middle laminae of the contralateral optic tectum (which contain IR‐responsive units) were distinctly labelled; the corresponding layers of the ipsilateral tectum were lightly labelled. A subcerebellar nucleus not known to be part of the IR system was heavily labelled bilaterally. No consistent labelling was found in the diencephalon or telencephalon.Since units in the LTTD do not respond to stimulation of the contralateral pit yet the LTTD is labelled with 2DG when there is contralateral pit stimulation, several controls were carried out. Unilateral injection of 3H‐proline into LTTD revealed no projection to the contralateral LTTD. In a monocularly, visually stimulated animal with both pits occluded, the LTTD still showed heavy but equal 2DG labelling bilaterally. In addition, the outer layers of the contralateral optic tectum were heavily labelled. No 2DG labelling of the LTTD was obtained when branches of the trigeminal nerve innervating the LTTD were previously cut.These results suggest that much of the 2DG labelling in the LTTD is due to spontaneous ongoing activity from the pit organ rather than from IR evoked activity. Using single‐unit recording, almost all LTTD units were found to have high spontaneous firing rates. IR stimulation increases the firing rate above spontaneous levels. When the afferent trigeminal nerves were cut, LTTD cell activity was almost totally silenced.
Projection patterns of lateral‐line afferents in anurans: A comparative HRP study
Authors: Fritzsch Bernd , Nikundiwe Alfeo M. , Will Udo 
Published: January 2005

AbstractPrimary projections of the anterior and posterior lateral‐line nerves were traced by means of transganglionic transport of horseradish peroxidase in species belonging to five of the six anuran superfamilies. Both anterior and posterior lateral‐line nerve afferents each enter the brain via a single root which divides into two or more bundles. These bundles carry fibers from neuromasts only. No separate dorsal fascicle and no ampullary organs as in urodeles and gymnophions have been found. All bundles join in the neuropil of the nucleus intermedius to form ascending and descending fascicles. Two distinct fascicles are found in species showing little collateralization. No fasciculation is found in species with an elaborate telodendritic arborization. Afferents of the anterior lateral‐line nerve run ventromedially and those of the posterior lateral‐line nerve dorsolaterally within the ipsilateral nucleus intermedius neuropil. Rostrally they terminate in the vicinity of the eminentia granularis and caudally in the vicinity of the calamus scriptorius.The metamorphic changes in the alar plate do not support the hypothesis of Larsell ('34) as to a change in function of second‐order lateral‐line neurons into second‐order auditory neurons. The rostral part of the nucleus intermedius shows numerous degenerating neurons at metamorphic climax whereas the caudal part becomes part of the nucleus caudalis of adult anurans. Besides the members of the Pipoidea, there is at least the genus Bombina which retains parts of the lateral‐line system.The term “dorsal island”, its relevance for any part of the anuran brain, and the possible relation between absence of electroreception and the development of the nucleus dorsolateralis are discussed.
The mormyrid mesencephalon. III. Retinal projections in a weakly electric fish, Gnathonemus petersii
Authors: Lázár G. , Libouban S. , Szabo T. 
Published: January 2005

AbstractThe optic nerve and the retinal projections were studied in a mormyrid fish, Gnathonemus petersii, by using Fink‐Heimer, HRP, cobalt labeling, and autoradiographic tracing techniques. The retinal fibers terminate bilaterally in the following places: suprachiasmatic nucleus, dorsolateral optic nucleus, optic nucleus of the posterior commissure, cortical nucleus, ventral pretectal area, optic tectum, and the accessory optic terminal field. The number of uncrossed fibers is relatively high in the suprachiasmatic nucleus, but negligibly small in the other retinal terminal fields. In the lateral geniculate nucleus and pretectal nucleus only crossed retinal fibers could be detected.The visual system of Gnathonemus is compared to that of other fishes, amphibians, and reptiles and the possible homologies are proposed. The comparison points to the conclusion that the visual system is less developed in Gnathonemus. This nocturnal species lives in turbid waters and has a special electric sense which may permit compensation for the reduced visual capacity.
The central projection of muscle afferent fibres to the lower medulla and upper spinal cord: An anatomical study in the cat with the transganglionic transport method
Authors: Nyberg Gunnar , Blomqvist Anders 
Published: January 2005

AbstractThe projection of muscle afferent fibres to the medulla oblongata and upper spinal cord was studied in the cat by using transganglionic transport of wheat germ agglutinin‐horseradish peroxidase conjugate. The results demonstrate a precise, musculotopic termination pattern in the external cuneate nucleus; thus, fibres from the intrinsic muscles of the paw terminate medially; those from forearm, arm, and shoulder muscles terminate progressively more laterally; and those from neck and thoracic muscles terminate in the ventrolateral and dorsolateral parts, respectively. Muscle afferent fibres to the main cuneate nucleus terminate in the ventral “reticular” region of the nucleus, with a sparse projection also to the ventral part of the rostral and caudal regions, including the base of the dorsal horn. Fibres from the neck muscles terminate slightly more laterally in the ventral region than do those from the limb muscles, but otherwise, and thus contrary to the case in the external cuneate nucleus, no topographic organization was detected. In the spinal cord, projection was found to laminae I and V, and from the musculature of the back of the neck to the central cervical nucleus.