bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topology of ascending brainstem projections to nucleus parabrachialis in the cat
Authors: King Gary W. 
Published: January 2005

AbstractThe afferent projections to nucleus parabrachialis (NPB) and nearby pontine areas from the lower brainstem were studied in cats using retrograde horseradish peroxidase (HRP) and anterograde autoradiographic tracing techniques. Two groups of medullary neurons send major projections to NPB and the Kölliker‐Fuse nucleus (KF): (1) the solitary complex, especially the medial nucleus of the solitary tract (SM), nearby smaller cells of the dorsal motor nucleus of the vagus (DMV) and the commissural nucleus; and (2) the lateral tegmental field (FTL), or parvocellular reticular formation. Autoradiographic tracing from these areas demonstrated terminal fields in NPB/KF and emphasized a ventrolateral route to NPB from both sources, with axons ascending between the facial nerve and superior olive and passing rostral to the trigeminal nuclei. Minor projections to NPB/KF originate in the ventrolateral nucleus of the solitary tract, area subpostrema, the alaminar spinal trigeminal nucleus, the gigantocellular and magnocellular tegmental fields, and an area dorsal to the ipsilateral inferior olive.Topographical features of the major projections were studied by correlating the locus of overlap of injection sites with the locations of HRP‐positive cells. Medial areas of SM/DMV project mostly to medial parts of NPB, while lateral areas near the solitary tract project to lateral parts of NPB and KF. Crossing projections from SM/DMV favor dorsolateral NPB and KF. FTL neurons in dorsomedial areas project more to medial NPB, and ventrolateral areas project to lateral NPB/KF.Using a new coordinate system to locate and normalize the positions of FTL neurons, data from many brains were collated. FTL cells projecting to NPB/KF were found to be on discrete longitudinal sheets, running radially with respect to the fourth ventricle. This substructure and related evidence suggest a preferred pattern for neuroanatomical connections and information processing in the lateral reticular areas of the brainstem, and help in understanding the topography of the projections to NPB/KF.
Spinocerebellar projections to the vermis of the posterior lobe and the paramedian lobule in the cat, as studied by retrograde transport of horseradish peroxidase
Authors: Matsushita Matsuo , Ikeda Michiko 
Published: January 2005

AbstractSpinal neurons projecting to the posterior lobe of the cerebellum were identified with the retrograde horseradish peroxidase technique in the cat. In four cases with the injections, which were preceded by hemisections at cervical or thoracic levels, it was determined whether in the spinal cord the identified neurons give rise to crossed ascending axons or uncrossed ascending ones.The main groups of neurons projecting to sublobule VIIIB were located in the central cervical nucleus (with crossed ascending axons), Clarke's column (with uncrossed ascending axons), and the medial part of lamina VII of L6 to the caudal segments (with crossed ascending axons). Additional labeled neurons were found in the medial part of lamina VI between C2 and T1 and of L5 and L6 (with uncrossed ascending axons), and in the ventral as well as dorsal horns of the sacral‐caudal segments (with crossed ascending axons). On the other hand, neurons projecting to sublobule C (the copular part) of the paramedian lobule, which appeared always ipsilaterally to the side of the injections, were located in lamina V of C8 to L4 (with uncrossed ascending axons). Marginal neurons of Clarke's column (with uncrossed ascending axons) and spinal border cells (with crossed ascending axons that recross in the cerebellum) projected specifically to this part. At L1 and L2 or L2 and L3 labeled large and medium‐sized neurons were also found within Clarke's column.The present study suggests that there are segregated projections of spinal neurons to the cortex of the cerebellar posterior lobe.
Auditory cortico‐cortical connections in the owl monkey
Authors: Fitzpatrick Kathleen A. , Imig Thomas J. 
Published: January 2005

AbstractTwo tonotopically organized cortical fields, the primary (A1) and rostral (R) fields, comprise a core of auditory cortex in the owl monkey. Injections of tritiated proline were made into each of these fields to determine their projections to the auditory fields in the ipsilateral and contralateral hemispheres using autoradiographic methods. Neurons in R project to the rostromedial (RM) and primary fields in both hemispheres, and to the posterolateral (PL) and anterolateral (AL) fields in the ipsilateral hemisphere. In addition, the rostral fields in the two hemispheres are connected. Neurons in the primary field project to RM and R in both hemispheres and to AL, PL, and the caudomedial (CM) field in the ipsilateral hemisphere. The primary fields in the two hemispheres are connected. Single injections into A1 and R often result in labelingof two or more columns of tissue in the ipsilateral and contralateral target fields. Cortico‐cortical axon terminations are concentrated in layer IV of fields AL and RM and in upper layer III and layer IV of R and CM. In A1, axon terminals of neurons whose cell bodies lie in A1 in the opposite hemisphere are concentrated in upper layer III and layer IV; axon terminals of neurons located in field R of the same hemispheres are concentrated in layers I and II. Layer IV of PL contains the greatest concentration of cortico‐cortical axon terminals; the supragranular layers contain a somewhat lower concentration. Neurons in R project contralaterally in the anterior commissure while A1 neurons send their axons contralaterally in the corpus callosum.
Ascending pathways from the monkey superior colliculus: An autoradiographic analysis
Authors: Harting John K. , Huerta Michael F. , Frankfurter Anthony J. , Strominger Norman L. , Royce G. James 
Published: January 2005

AbstractThe autoradiographic tracing method has been used to analyze the distribution of ascending tectofugal pathways in the rhesus monkey.Our findings show that axons which arise from deep collicular neurons terminate within several dorsal thalamic nuclei which in turn project upon the frontal eye fields (area 8) and the inferior parietal lobule (area 7). Both of these cortical areas are functionally quite similar to the deep colliculus, and we suggest that ascending channels from the deep tectum must account, at least in part, for these functional similarities.The present autoradiographs reveal projections to several nuclear zones previously not identified as deep collicular targets in the monkey. Such targets include the visceral cell columns of the oculomotor complex, the rostral interstitial nucleus of the medial longitudinal fasciculus, and the magnocellular division of the ventral anterior nucleus.Deep tectal input also has been shown to terminate quite extensively within the paralamellar region of the mediodorsal nucleus and in the parafascicular nucleus; very little input to the central lateral and centromedian nuclei was observed.Radioisotope injections restricted to the superficial layers reveal dense projections to the parabigeminal nucleus, the pretectum, the inferior and lateral pulvinar nuclei, and to the ventral and dorsal lateral geniculate nuclei. Transported protein within the dorsal lateral geniculate nucleus occupied the “S” layers and the interlaminar zones.
Unmyelinated sensory and preganglionic fibers in rat L6 and S1 ventral spinal roots
Authors: Coggeshall Richard E. , Maynard Christine W. , Langford Lauren A. 
Published: January 2005

AbstractApproximately 30% of the axons in the L6 and S1 ventral roots in the rat are unmyelinated. Appropriate surgical procedures show that 30% of these unmyelinated axons arise from dorsal root ganglion cells and are therefore presumably sensory. Thus approximately 10% of the total number of axons in these ventral roots are sensory. The other 70% of the unmyelinated axons come from the spinal cord and are therefore presumably preganglionic parasympathetic fibers. Thus approximately 20% of the axons in these ventral roots are unmyelinated preganglionic fibers. The implications of these findings are discussed.
The organization of the lateral posterior nucleus of the golden hamster after neonatal superior colliculus lesions
Authors: Crain Barbara J. , Hall William C. 
Published: January 2005

AbstractThe reorganization of the adult hamster's lateral posterior nucleus after neonatal superior colliculus lesions was studied using primarily light and electron microscopic degeneration techniques. Two types of experiments were conducted.First, the distributions of the remaining afferents from the contralateral superior colliculus, the contralateral retina, and the ipsilateral posterior neocortex were determined using the Fink‐Heimer ('67) technique. Normally the projections from the contralateral superior colliculus and retina are sparse and restricted to small areas in the rostrolateral subdivision. After neonatal lesions of the ipsilateral colliculus, however, these two minor projections greatly increase in density and expand to share a common border. In contrast, the normal projection from the posterior neocortex is dense throughout the rostrolateral subdivision. After a neonatal colliculus lesion, however, this projection is greatly decreased in the region occupied by the optic tract terminals.Second, the ultrastructural organization of the rostrolateral subdivision was studied in adult animals which had received neonatal colliculus lesions. Normally, this region is characterized by synaptic clusters in which numerous medium‐sized terminals (M‐terminals), almost all from the ipsilateral colliculus, synapse around the shaft of a large central dendrite. The contralateral colliculus and retina normally contribute only a few M‐terminals. After a neonatal colliculus lesion, typical clusters still form, but now the expanded projections from the contralateral colliculus and retina contribute numerous M‐terminals. The cortex does not contribute M‐terminals in either normal or experimental animals.These results suggest that the afferents to the rostrolateral subdivision normally compete for synaptic space. The various factors that might be involved in determining the outcome of such competition are discussed.
Organization of the face representation in macaque motor cortex
Authors: McGuinness Evelynn , Sivertsen Dave , Allman John M. 
Published: January 2005

AbstractWe stimulated with microelectrodes the face representation in precentral motor cortex in macaque monkeys. Responses were very discrete; at threshold current levels the usual response was a small focus of movement in part of a muscle. Facial muscles cluster together in the posterior and anterior portions of the precentral gyrus with tongue movements represented in the intervening region and along the lateral extent. Within each cluster there are multiple representations of individual muscle movements. In long penetrations down the anterior wall of the central sulcus we were able to advance the electrode tangentially through cortex. In these penetrations we encountered a series of discrete zones each of which was related to the movement of a particular muscle or part of a muscle in the face. The lowest threshold points were found in the center of each zone, and a the microelectrode progressed toward the edge, thresholds rose until there was a shift to a new muscle movement. Successive stimulation points separated by as little as 50 μm could yield different responses. These zones could be either roughly cylindrical or take the form of narrow curving bands running mediolaterally across cortex. There is a tendency for adjacent muscles to occur together, and the representation may be roughly topographical within the limits set by the morphological structure of the muscles themselves. The most commonly evoked muscle response was in zygomaticus, which retracts the corners of the mouth in expressions of fear and anger.
Development of the brain Stem in the rat. II. Thymidine‐radiographic study of the time of origin of neurons of the upper medulla, excluding the vestibular and auditory nuclei
Authors: Altman Joseph , Bayer Shirley A. 
Published: January 2005

AbstractGroups of pregnant rats were injected with two successive daily doses of 3H‐thymidine from gestational days 12 and 13 (E12 + 13) until the day before birth (E21 + 22). In radiographs from adult progeny of these rats the proportion of neurons generated on specific days was determined in the major nuclei of the upper medulla, with the exception of the vestibular and auditory nuclei. The neurons of the motor nuclei are generated over a brief period. Neurons of the retrofacial nucleus are produced first, with more than 60% of the cells arising on day E11 or earlier. Peak generation time of abducens neurons is day E12 and of the neurons of the facial nucleus is day E13. In contrast, the neurons of the superior salivatory nucleus are produced late, predominantly on day E15 and some on day E16. The generation of the (sensory relay) neurons of the nucleus oralis of the trigeminal complex takes place over an extended period between days E12 and E15; the last generated cells include the largest neurons of this nucleus. Neurons of the raphe magnus are produced between days E11 and E14, the neurons of the rostral medullary reticular formation between days E12 and E15. The latest generated neurons of the upper medulla (excluding the cochlear nuclei) belong to a structure identified as the granular layer of the raphe.Combining these results with those of the preceding paper (Altman and Bayer, ′80a) and with additional data, it is postulated that the laterally and ventrally situated motor nucleus of the trigeminal, the facial nucleus, and the nucleus ambiguus form a single longitudinal zone of branchial motor neurons with a rostral‐to‐caudal cytogenetic gradient. In contrast, the medially and dorsally situated (juxtaventricular) hypoglossal nucleus and abducens nucleus (together with the other nuclei of the ocular muscles) form a longitudinal somatic motor zone with a caudal‐to‐rostral gradient. The dorsal nucleus of the vagus and the superior salivatory nucleus may constitute a preganglionic motor zone, also with a caudal‐to‐rostral cytogenetic gradient.
A scanning electron microscope study of the in vitro development of dissociated hippocampal cells
Authors: Rothman S. , Cowan W. M. 
Published: January 2005

AbstractCultures of dissociated hippocampal neurons from 18‐day‐old rat fetuses were examined by scanning electron microscopy after periods between one hour and 20 days following plating on a poly‐L‐lysine coated substrate. Cell attachment was virtually complete within one hour after plating, and at that stage many cells could be seen which had started to extend processes with broad growth cones. By four hours in culture, process formation was well advanced and some cells had already assumed a pyramidal configuration. After 16 hours in culture, numerous contacts were seen between neighboring growth cones, and this frequently led to fasciculation of the interacting fibers. During the next three weeks the cell bodies enlarged considerably and rounded‐up, and two distinct types of processes became evident: large, rapidly tapering dendrite‐like processes and finer, essentially uniform‐diametered processes that resemble axons. In most of the older cultures a dense plexus of processes was formed, and many of the finer processes appeared to have “bouton‐like” swellings as they traversed the upper surfaces of the neuronal perikarya. Non‐neuronal elements, which comprised only about 5% of the cells initially plated, rapidly proliferated in our cultures and within three to six days formed a confluent monolayer beneath the neurons.
A light and electron microscopic study of the dorsal motor nucleus of the vagus nerve in the cat
Authors: McLean John H. , Hopkins David A. 
Published: January 2005

AbstractThe morphology of the dorsal motor nucleus of the vagus nerve (DMV) in the cat was studied with the aid of light and electron microscopy. In frozen sections stained by the Kluver‐Barrera method or stained to show retrograde labeling in the DMV following injections of horseradish peroxidase (HRP) in the cervical vagus nerve and the stomach wall a range of sizes of DMV neurons was observed but it was not possible to distinguish separate types. In contrast, two distinct types of neurons, one medium‐sized and the other small, were identified with the light microscope in Golgi‐Cox and 1‐μm Epon sections and with the electron microscope in ultrathin sections.The medium‐sized neurons had a range of sizes but generally measured 18 × 25 μm and possessed three to four proximal dendrites which branched two or three times. Spines were observed occasionally on the soma and on dendrites. These neurons contained a well‐developed cytoplasm and a noninvaginated round to oval nucleus. The small neurons generally measured 9 × 14 μm and were round or slightly elongated in shape. Their dendritic processes were fewer and thinner than those of the medium‐sized neurons and extended for shorter lengths. Their soma contained scanty cytoplasm and an invaginated nucleus. The medium‐sized neurons outnumbered the small neurons by more than three to one but both neuronal types were distributed evenly throughout the nucleus. The medium‐sized neurons seemed to correspond in size to the parasympathetic efferent neurons of the viscera as indicated by the HRP studies.Axosomatic synapses on both types of neurons and axodendritic synapses were observed in the DMV. Terminals containing mainly small clear round vesicles and making asymmetrical contact with the postsynaptic membrane were involved in the majority of synapses on both the soma and dendrites. Terminals containing predominantly pleomorphic vesicles and making symmetrical contact with the postsynaptic membrane were also common, comprising up to one‐third of all synapses observed. Serial sections revealed that most synaptic terminals contained varying numbers of large (75–110 nm) dense‐cored vesicles. Smaller dense‐cored vesicles (45–55 nm) were sometimes observed, often close to the area of synaptic contact. Terminals 1–2 μm in diameter which contacted dendrites 1–3 μm in diameter formed the most common synaptic combination throughout the rostral to caudal extent of the DMV. No distinct regional differences were observed with respect to distribution of synaptic types.
The cytoarchitecture, cytology, and synaptic organization of the basilar pontine nuclei in the rat. I. Nissl and golgi studies
Authors: Mihailoff Gregory A. , McArdle Craig B. , Adams Catherine E. 
Published: January 2005

AbstractStudies of the rat basilar pontine gray in Nissl‐stained frozen sections revealed the presence of four major subdivisions referred to as medial, ventral, lateral, and peduncular nuclei with respect to their position relative to the cerebral peduncle. Neurons located adjacent to the surface of, or within the cerebral peduncle were considered collectively as the peduncular nucleus. It should be emphasized that the above subdivisions are useful only for descriptive purposes and do not necessarily reflect distinct cytological similarities or differences within the identified cell groups. The dorsal peduncular (pontine) region was continuous around the lateral and medial boundaries of the peduncle with more ventral pontine areas. A distinct cluster of neurons was consistently observed near the ventromedial surface of the basilar pons, seemingly walled‐off by fascicles of pontocerebellar axons. In addition, in most animals, a cleft appeared in the peduncle and allowed direct communication between dorsal and ventral peduncular regions, while the medial lemniscus formed a partial boundary separating dorsal pontine neurons from the nucleus reticularis tegmenti pontis.Golgi studies indicated that four general varieties of pontine neurons could be distinguished, and in order of relative frequency were described as spine‐laden, pauci‐spined, pauci‐spined with long, thin dendrites, and small bipolar or unipolar cells whose axon sometimes collateralized within the pons. A wide variety of spinous processes and finger‐like dendritic protrusions, some of which formed a terminal tuft‐like arrangement, characterized pontine neuron dendrites. In addition, some dendrites of small neurons gave rise to rather long, thin, beaded processes which in certain instances emanated from an unusual triangulated branch point enlargement. Dendritic orientation (neuron shape) was sometimes determined by location, with cells in the peduncular nucleus oriented parallel to the nearest peduncular surface, while cells near the ventral pontine surface were arranged parallel to transversely directed pontocerebellar axons. Cells of medial pontine regions did not project dendrites across the midline, while neurons near the peduncular cleft sent dendrites into that space. Based on the locations of various pontine afferent termination zones as determined in previous as well as ongoing studies, it appears that some pontine neurons exhibit dendritic systems reaching into more than one afferent projection area, thereby affording them an opportunity to receive inputs from several afferent systems.
Organization of spinothalamic tract axons within the rat spinal cord
Authors: Giesler G. J. , Spiel H. R. , Willis W. D. 
Published: January 2005

AbstractTwo techniques have been used to examine the organization of spinothalamic tract axons within the spinal cord of the rat. In the initial experiments, the thalamus was filled on one side with horseradish peroxidase (HRP) using a series of small injections. The injections were preceded by lesions of various areas of the ventral quadrant. These studies indicated that the cells of origin of STT axons ascending within the ventral funiculus (VF) are located primarily in the ventral‐most areas of the dorsal horn and the intermediate gray zone. The cells of origin of STT axons projecting within the ventrolateral funiculus (VLF) are located not only deep within the gray matter but in addition within the dorsal‐most two thirds of the dorsal horn, the area of the spinal cord gray matter shown in previous studies to contain the vast majority of cells with cutaneous tactile and nociceptive input. To examine these projections directly, rats received either a series of HRP injections that filled the thalamus on one side or a small injection into either medial or lateral thalamus. Examination of the labeled axons in horizontal sections through the cervical cord indicated that STT axons ascending to lateral thalamus do so in the VLF. In contrast, axons terminating in medial thalamus ascend in the VF. Additional experiments have shown that axons ascending to the lateral thalamus are distributed throughout the VLF at lumbar levels. Within the thoracic cord, lateral projecting STT axons are distributed throughout much of the VLF but are not found in close proximity to the ventral horn. At cervical levels all lateral‐projecting STT axons have assumed a position on the lateral rim of the VLF. These and previously published data have demonstrated that the rat spinothalamic tract is composed of two components that differ in the distribution of their cells of origin, the area of the cord in which they ascend, and the thalamic nuclei in which they terminate.