bluuebunny/crossref_metadata_2025_split huggingface dataset:
The thalamocortical projection in Pseudemys turtles: A quantitative electron microscopic study
Authors: Smith Leslie M. , Ebner Ford F. , Colonnier Marc 
Published: January 2005

AbstractThalamic fibers in the cortex of Pseudemys turtles were studied with the electron microscope to determine the type of synaptic vesicle they contain, the type of membrane differentiation they form, and the type of processes they contact. Following unilateral removal of the thalamus, all degenerating thalamic axon terminals are located in the outer third of the molecular layer in the rostral half of general cortex. In the middle of this zone they constitute as much as 25% of all vesicle‐containing profiles. The degenerated terminals appear as electron opaque profiles, most commonly with a uniform opacity. They contain round agranular vesicles and form synapses with asymmetrical membrane differentiations. They synapse mainly on dendritic spines containing mitochondria and/or membranous sacs, although some thalamic fibers contact small clear spines, dendrites, and, rarely, cell bodies. Counts show that 86% of degenerated contacts are on dendritic spines and 14% on dendritic shafts. The spines probably all belong to the dendrites of the pyramidal cells, whose somata are located in the deep cellular layer. The dendritic shafts and somata are most likely those of the aspinous stellate neurons located in the molecular layer. Although these stellate cells are not sufficiently numerous to form a cell “layer,” each transverse section through thalamic recipient cortex contains about nine of these cells and they occur in a ratio of 1:37 to pyramidal cells in the underlying main cell layer. We have calculated that in a rectangular solid of turtle cortex whose dimensions are 1 mm × 1 mm × the depth from pial surface to the underlying ventricle, there are 5.2 million thalamic fiber contacts (all in the outer 100 μm), 15,000 pyramidal neurons in the main cell layer, and 400 stellate cells in the molecular layer. Of the 5.2 million thalamic synapses, 0.7 million contact stellate cells and 4.5 million contact pyramidal cells. Thus each stellate cell in the molecular layer receives on the average 1,800 thalamic fiber contacts, while each pyramidal cell receives only 300 thalamic fiber synapses on the distal portion of its dendrites. The calculations lead to the conclusion that individual stellate cells receive at least six times more thalamic fiber synapses than individual pyramidal cells in turtle cortex. We suggest that the stellate cells in the thalamic input zone are inhibitory and that each thalamic volley not only excites efferent pyramidal cells but is also a powerful activator of inhibitory interneurons.
Selective retrograde labeling indicating the transmitter of neuronal pathways
Authors: Streit P. 
Published: January 2005

AbstractA number of tritiated transmitter related compounds—amino acids and biogenic amines—were injected into the rat caudoputamen or substantia nigra in order to test (1) for the occurence of autoradiographic perikaryal labeling, (2) for a selectivity of perikaryal labeling relating certain compounds to certain pathways, and (3) for the relation of perikaryal labeling to known transmitter specificities of the systems involved. Perikaryal labeling was observed after injection of some but not all of the substances used and was best explained by retrograde labeling in pathways projecting to the injection sites. Six hours after injection of high concentrations of tritiated transmitter into the terminal area, perikaryal labeling was observed: (A) in substantial nigra compacta (A9), A10 (rostral) and A8 (all heavy), and in n. raphe dorsalis (light) after [3H]‐dopamine and [3H]‐norepinephrine injection into caudoputamen; (B) same pattern as in A, but heavy in n. raphe dorsalis after [3H]‐serotonin injection into caudoputamen; perikaryal labeling absent in cortex and thalamus after injection of substances mentioned in A and B; (C) only in substantia nigra compacta (minimally) after [3H]‐GABA injection into caudoputamen; (D) in cerebral cortex and thalamus but not in substantia nigra, A10, A8, nor in n. raphe dorsalis after injection of [3H]‐D‐aspartate into caudoputamen; (E) in the rat caudoputamen but not in n. raphe dorsalis after [3H]‐GABA injection into substantia nigra; (F) in n. raphe dorsalis but not in caudoputamen after [3H]‐serotonin into substantia nigra.These results indicated, indeed, a certain selectivity—partly related to transmitter specificity—for perikaryal labeling patterns. As a method, transmitter specific retrograde tracing could be useful in pathways with dopamine‐, serotonin‐, and GABA‐mediated synaptic transmission.
Ascending projections of the inferior colliculus in the cat: An autoradiographic study
Authors: Kudo Motoi , Niimi Kahee 
Published: January 2005

AbstractThe ascending projections of the inferior colliculus (IC) in the cat were traced by the autoradiographic method, with special reference to the differential projections of each subnucleus of IC.The laminated ventrolateral part of the central nucleus of IC (CNv) projects to the ventral and medial divisions of the ipsilateral medial geniculate body (MGB). The projections to the ventral division are topographically organized in the mediolateral direction, the terminals being arranged in the form of lamina, while those to the medial division are diffuse. The unlaminated dorsomedial part of the central nucleus of IC (CNd) sends fibers to every division of the ipsilateral MGB, particularly to the dorsal division and the ventromedial portion of the ventral division. It is noteworthy that the external nucleus of IC (EN) projects to the superior colliculus, part of the pretectum, and the anterior extremity of MGB ipsilaterally, in addition to the ventral and medial divisions of MGB. The posterior cap of IC, regarded as the pericentral nucleus of IC (PC), projects ipsilaterally to the ventral part of the caudal tip of MGB and the posterior part of the suprapeduncular nucleus. In addition to these projections, the parabrachial region and interstitial nucleus of the brachium of IC (BIC) are identified as common targets of projections of each nucleus of IC on the ipsilateral side. Contralaterally, every subnucleus of IC except for PC projects via the commissure of IC to areas corresponding to the targets of the ipsilateral projections, such as the ventral and medial divisions of MGB and the parabrachial region and the interstitial nucleus of BIC, although these contralateral projections are in general much sparser than those ipsilateral. Intrinsic and commissural connections within IC are also revealed in this study, providing characteristic configurations of each subnucleus of IC.It is concluded that the ascending projections of IC in the cat are highly differentially organized according to its subnucleus.
Estrogen target cells in the forebrain of river lamprey, ichthyomyzon unicuspis
Authors: Kim Ye Soon , Stumpf Walter E. , Reid Frederic A. , Sar Madhabananda , Selzer Michael E. 
Published: January 2005

AbstractEstrogen‐concentrating cells in the brain of river lamprey, Ichthyomyzon unicuspis, are identified and mapped by thaw‐mount autoradiography. After injection of 3H–estradiol–17β, cells with nuclear concentration of radioactivity are found in the ventral periventricular area of the telencephalon, and in preoptic, central hypothalamic, and thalamic regions of the diencephalon, while in the pallium no such target cells are found. Injection of unlabeled estradiol prior to the administration of 3H–estradiol reduces or eliminates the nuclear concentration of radioactivity.The autoradiographic results demonstrate the presence of estrogen target cells in the brain of descendents of one of the phylogenetically earliest vertebrate lines. The topographical distribution of these target neurons, which are accumulated in certain periventricular structures, is similar to the distribution of estrogen target neurons described previously for other nonmammalian and mammalian vertebrates. Accordingly, estrogen feedback and activation sites are present throughout vertebrate phylogeny.
Central representation and somatotopic organization of the jaw muscles within the facial and trigeminal nuclei of the pigeon (Columba livia)
Authors: Wild J. Martin , Zeigler H. Philip 
Published: January 2005

AbstractThe location of facial and trigeminal brainstem motoneurons innervating the jaw muscles of the pigeon has been determined, using the technique of retrograde transport of horseradish peroxidase. Trigeminal motoneurons innervating the jaw closing muscles are located within the classically defined main trigeminal motor nucleus, and their organization exhibits approximately a mediolateral somatotopy. Trigeminal neurons innervating the opener muscle of the upper jaw are also located in the main trigeminal motor nucleus, but comprise a dorsomedial subnucleus which is continuous caudally with the dorsal facial nucleus whose neurons innervate the opener muscle of the lower jaw. The Vth and VIIth motor nuclei are thus linked in the rostrocaudal plane. The representations of other head muscles are arranged in a dorsoventral manner within the V–VII motor complex, with the lower eyelid muscle represented most dorsally and the hyoid and superficial neck muscles most ventrally.Jaw closing muscles were well represented in both the Gasserian ganglion and trigeminal mesencephalic nucleus. No such representation was found for either of the jaw opening muscles. The HRP data indicate that the V–VII motor complex in birds is far more extensive than has previously been suggested.
Tonotopic organization in auditory cortex of the cat
Authors: Reale Richard A. , Imig Thomas J. 
Published: January 2005

AbstractMicroelectrode mapping techniques were employed in the cat's auditory cortex to relate the best frequencies of a large population of neurons with their spatial loci. Based upon the best‐frequency distribution, the auditory region was divided into four complete and orderly tonotopic representations and a surrounding belt of cortex in which the tonotopic organization was more complex. The four auditory fields occupy a crescent‐shaped band of tissue which comprises portions of both the exposed gyral surfaces and sulcal banks of the ectosylvian cortex. The anterior auditory field (A) is situated most rostrally upon the anterior ectosylvian gyrus. It extends upon the ventral bank of the suprasylvian sulcus and upon the banks of the anterior ectosylvian sulcus. Adjoining field A caudally is the primary auditory field (AI), which extends across the middle ectosylvian gyrus and portions of both banks of the posterior ectosylvian sulcus. The representations of the highest best frequencies in fields A and AI are contiguous. Caudal and ventral to AI are located the posterior (P) and ventroposterior (VP) auditory fields. They lie mainly upon the caudal bank of the posterior ectosylvian sulcus but also extend upon the rostral bank and upon the posterior ectosylvian gyrus. The low best‐frequency representations of fields AI and P are contiguous, whereas the low best‐frequency representation of field VP lies near the ventral end of the posterior ectosylvian sulcus. Fields P and VP are joined along their middle and high best‐frequency representations. Within each auditory field isofrequency lines defined by the spatial loci of neurons with similar best frequencies are oriented orthogonal to the low‐to‐high best‐frequency gradients.
Topographic organization of the orientation column system in the striate cortex of the tree shrew (Tupaia glis). I. Microelectrode recording
Authors: Humphrey Allen L. , Norton Thomas T. 
Published: January 2005

AbstractMicroelectrode recordings were made in the binocular portion of the tree shrew striate cortex to determine how orientation selective cells are distributed topographically in area 17 of this species. Seventy‐five percent of the cells sampled were activated well by elongated visual stimuli and were quite selective for stimulus orientation. Ninety‐five percent of the orientation‐selective cells had orientation tuning ranges (Wilson and Sherman, '76) between ± 5° and ± 40° from their optimal orientation.Orientation‐selective cells with the same or similar optimal orientations were distributed in cortex in a columnar manner (Hubel and Wiesel, '62), as determined from electrode penetrations nearly normal to the cortical surface. Penetrations parallel to the cortical surface revealed a highly ordered representation of optimal stimulus orientation, generally characterized by sequential changes in optimal orientation with electrode movement across the striate cortex. In addition, relatively consistent differences were observed in the rates and patterns of orientation shift on these penetrations depending on the direction of electrode movement across the cortex. Penetrations parallel to the 17–18 border yielded moderate‐to‐high rates of orientation change (mean slope = 434°/mm), with the changes genearlly progressing through a complete clockwise or counterclockwise cycle of 180° or more before a major reversal in the direction of orientation shift was encountered. In contrast, penetrations perpendicular to the border yielded low‐to‐moderate slopes (mean slope = 239°/mm). On these penetrations a more limited range of optimal orientations (<180°) was usually encountered, due to frequent reversals in the direction of orientation shift. Also, extended regions (100–200 μm long) of constant optimal orientation were observed in these penetrations. The different patterns of orientation change found on these orthogonal penetrations across the striate cortex indicate that the orientation column system in this species is anisotropically organized with respect to the 17–18 border. Further, the regions of constant optimal orientation frequently encountered on penetrations perpendicular to the 17–18 border suggest that the anisotropy is subserved by a system of elongated zones of iso‐orientation arranged approximately perpendicular to the 17–18 border.
Topographic organization of the orientation column system in the striate cortex of the tree shrew (Tupaia glis). II. Deoxyglucose mapping
Authors: Humphrey Allen L. , Skeen Leslie C. , Norton Thomas T. 
Published: January 2005

AbstractThe topographic organization of the orientation column system in tree shrew striate cortex was examined by using 2–deoxyglucose autoradiography to map the cortical sites of increased metabolic activity produced by visual stimulation with stripes of a single orientation. Awake experimental tree shrews (freely moving, restrained, or paralyzed) were given injections of deoxyglucose label and then stimulated with vertical, horizontal, or oblique stripes for 45–75 min. Autoradiographs of coronal sections through the striate cortex revealed regularly spaced radial zones of increased deoxyglucose uptake 150–350 μm wide, extending from the cortical surface to the white matter, separated by interzone regions of lower uptake. The radial zones were most densely labeled and distinct in layers I–IIIb and least distinct in layer IV, which was continuously and densely labeled throughout both the radial zone and interzone regions. These radial zones, which were not present in control animals that viewed many orientations, reflect the locations of cortical cells activated by a single stimulus orientation.Reconstructions of the radial zones from serial sections produced maps of the distribution of increased deoxyglucose uptake across striate cortex. The maps reveal a highly organized system of narrow, parallel bands that are slightly wavy and have a mean spacing of 530 μm. The band pattern was confirmed in sections cut tangential to the cortical surface and was similar in animals stimulated with either vertical or horizontal stripes; the bands consistently abut the 17–18 border at nearly right angles and extend across the striate cortex in a generally posteromedial direction. These patterns of increased deoxyglucose consumption confirm the anisotropic distribution of orientation‐selective cells across the tree shrew striate cortex, suggested in the preceding microelectrode study (Humphrey and Norton, '80). The density distribution of label within the bands further suggests that the anisotropy is due to a system of parallel, somewhat wavy iso‐orientation lines arranged roughly perpendicular to the 17–18 border.
Axon reaction in dorsal motor vagal and hypoglossal neurons of the adult rat. light microscopy and RNA‐cytochemistry
Authors: Aldskogius Håkan , Barron Kevin D. , Regal Ronald 
Published: January 2005

AbstractQualitative light microscopical observations, morphometric measurements, and cytophotometric values for nucleolar and cytoplasmic RNA were compared in axotomized rat dorsal motor vagal and hypoglossal neurons. These data were correlated with consective cell counts and examination of the peripheral nerves.Vagal neurons showed an early prominent chromatolysis, later accompanied by increased cytoplasmic basophilia. Morphometric data showed a transient slight cytoplasmic enlargement but no nucleolar hypertrophy. Nucleolar RNA was unchanged, but cytoplasmic RNA was elevated 7 to 84 days postoperatively. Cell counts demonstrated a final cell loss of about 70%.Hypoglossal neurons showed a moderate chromatolysis. Nucleolar and cytoplasmic areas were enlarged for a short period. Nucleolar and cytoplasmic RNA were elevated about 3 to 14 days and about 3 to 28 days postoperatively, respectively. Cell counts demonstrated a loss of 25% at the longest postoperative survival period.The results indicate that axotomized adult mammalian extrinsic neurons—even those destined to die—accumulate RNA. This response contrasts with axon reaction in many axotomized mammalian intrinsic neurons which appear to undergo depletion of RNA.
The normal organization of the lateral posterior nucleus of the golden hamster
Authors: Crain Barbara J. , Hall William C. 
Published: January 2005

AbstractAs a first step in analyzing the influence of various afferent projections on the development of the hamster lateral posterior nucleus, its normal organization was studied using both light and electron microscopic techniques. Rostrolateral, rostromedial, and caudal subdivisions were identified. The rostrolateral subdivision receives dense projections from the ipsilateral superior colliculus and posterior neocortex, as well as sparser, more restricted projections from the contralateral colliculus and retina. The ipsilateral colliculus is by far the major source of medium‐sized (M)terminals with round vesicles. These terminals synapse around the shafts of large central dendrites to form distinctive synaptic clusters. The contralateral colliculus and retina contribute a few M‐terminals to the clusters. In contrast, axons from the posterior neocortex form very large (RL‐)terminals with round vesicles from the posterior neocortex form very large (RL)terminals with round vesicles which synapse onto numerous appendages of a single proximal dendrite, are surrounded by glial lamellae, and rarely participate in the clusters. Axons from all four sources also form small (RS)terminals with round vesicles which synapse on the shafts of small dendrites. Finally, F‐terminals with flat or pleomorphic vesicles form symmetric synaptic contacts both within and outside the clusters. The only identified projection to the rostromedial subdivision is from the ipsilateral posterior neocortex, which contributes RL‐ and RS‐ terminals. F‐terminals are also found, but neither M‐terminals nor synaptic clusters are present. The caudal subdivision also receives RL‐ and RS‐terminals from the ipsilateral posterior neocortex. Small inputs from the ipsilateral and contralateral colliculi are present, but their axons form only RS‐terminals. No M‐terminals or synaptic clusters are found.These results indicate that a large neonatal superior colliculus lesion would eliminate the vast majority of the M‐terminals in the synaptic clusters of the ipsilateral lateral posterior nucleus. In subsequent studies (Crain and Hall, '80 a, b, c), we will examine how the remaining inputs from the retina, contralateral superior colliculus, and posterior neocortex contribute to the synaptic organization when it develops after such a lesion.
Clonal analysis of the avian neural crest: Migration and maturation of mixed neural crest clones injected into host chicken embryos
Authors: Bronner‐Fraser Marianne , Sieber‐blum Maya , Cohen Alan M. 
Published: January 2005

AbstractQuail neural crest cells were grown in vitro at clonal density for 7 or 10 days. Mixed neural crest colonies and clones (containing both pigmented and unpigmented cells) were implanted into the trunk region of 2 1/2‐day‐old host chicken embryos by a previously described injection technique (Bronner and Cohen, '79). Here we describe the migratory behavior and subsequent phenotypic expression of the injected cells. Unpigmented cells and pigmented cells both migrated along the ventral neural crest pathway; there were, however, some differences in migratory behavior between the two cell types. After 3 days in vivo, unpigmented quail neural crest cells contributed to the sympathetic ganglion, adrenal medulla, and/or aortic plexus in the host. Many of the unpigmented cells became catecholamine‐containing neuroblasts. Unpigmented cells were never observed in the gonads or the gut, but localized only in regions normally populated by trunk neural crest precursors to neurons and supportive cells. Melanocytes derived from the same precursor, however, were often found in the gonads or gut, in addition to normal neural crest locations in the trunk. These results demonstrate that quail neural crest cells grown in tissue culture for 7 days or more retain the ability to migrate and contribute to normal neural crest structures when placed in the embryonic environment. Under the conditions described, a single neural crest cell gave rise to daughter cells expressing the melanotic phenotype (detected in tissue culture) and adrenergic phenotypes (detected after injection in vivo). This demonstrates that at least some single cells of the premigratory crest in the trunk region are pluripotent.
Ipsilateral projection from the subiculum to the retrosplenial cortex in the guinea pig
Authors: Sørensen Knud Erik 
Published: January 2005

AbstractA projection from the subiculum to the retrosplenial cortex (area 29a and b) was studied by autoradiographic tracing of anterogradely transported proteins following injections of radioactive amino acids into ventral and dorsal parts of the subiculum. Only the dorsal parts of the subiculum projected to the retrosplenial cortex. The projection was exclusively ipsilateral, and topographically arranged along both the longitudinal septotemporal axis and the transverse plane of the subiculum. The termination in the retrosplenial cortex was confined to the relatively cell free superficial layer (lamina 1) and the underlying cell‐rich layers (laminae 3–4). Between these two terminations a narrow zone (lamina 2) was only weakly labeled. The projection constitutes an output route for hippocampal activity in addition to the fimbria‐fornix system and the subicular projections to the parahippocampal areas.