bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of visual experience in promoting segregation of eye dominance patches in the visual cortex of the cat
Authors: Swindale N. V. 
Published: January 2005

AbstractTransneuronal autoradiography was used to study the role of visual experience in the development of ocular dominance patches in the cat. In order to assess quantitatively the effects of visual deprivation, image analysis was used to measure the profiles of grain density in layer IV. Fourier power spectra of these profiles were computed to give a measure of the amplitudes and frequencies of the fluctuations in grain density that were present.Deprivation of normal patterned vision by binocular lid suture or by rearing in total darkness from shortly after birth abolished the dominant periodicity (of about 1.1 mm) in the distribution of left and right eye afferents in layer IV of area 17. A dominant periodicity of about 2.2 mm was, however, present in area 18 of both normal and dark‐reared animals.Visual deprivation was not able to reverse segregation. One animal reared normally for 6 weeks was placed in the dark for a further 28 weeks and showed normal periodicities in the distribution of geniculate inputs to area 17. Another animal given 128 hours of experience and kept in the dark for the rest of the time until it was 12 weeks old also showed normal segregation.To determine the minimum amount of visual experience necessary for segregation to occur, four animals were given 8‐, 24‐, 48‐, and 128‐hour periods of visual experience and were studied at 12 weeks of age. Eight hours of experience had no detectable effect on segregation; periodicities of intermediate amplitude were present in animals that received 24 and 48 hours of experience, while 128 hours of experience resulted in periodicities of normal amplitude.Recovery from visual deprivation was studied by rearing kittens from birth in the dark for varying periods and then returning them to the normally lit colony room for periods of 6 to 22 weeks. Recovery from 6 weeks of dark rearing was found to be complete; much less recovery occurred following periods of 8 to 25 weeks of intial deprivation, and no recovery at all occurred after 30 weeks of deprivation.It is concluded that the spontaneous activity present in the geniculocortical afferents of dark‐reared and lid‐sutured cats is not adequate to drive normal periodic segregation in area 17, though it can do so in area 18. Between 48 and 128 hours of visual experience, given before 8 weeks of age, appears to be necessary and sufficient for normal periodic segregation of geniculate afferents in area 17 of the cat.
Development of somatostatin immunoreactive neurons in the rat occipital cortex: A combined immunocytochemical‐autoradiographic study
Authors: Cavanagh Marion E. , Parnavelas John G. 
Published: January 2005

AbstractThe postnatal development of somatostatin (SRIF)‐immunoreactive neurons, previously labeled with [3H]thymidine on embryonic days E14–E22, has been studied in the rat occipital cortex. Immunocytochemistry combined with autoradiography showed an “inside‐out” maturation pattern. Only SRIF neurons generated at E14 were present in layer VI in newborn rats. Later generated SRIF neurons appeared progressively higher in the cortex until about postnatal day 12 when SRIF neurons from E21 appeared in layer II. At 2 weeks of age, therefore, all SRIF neurons from E14–E21 were present. Most of these had been generated between E15 and E17 with a moderate number at E14 and rapidly diminishing numbers from E18 to E21. Although an overall layered distribution was apparent at peak production, there was a tendency for diffuse distribution most noticeable at E17. Diffusely distributed neurons were more likely to be below their appropriate layer than above it, thus contributing extra SRIF neurons to layer VI. At 3, 4, and 5 weeks, progressively fewer SRIF neurons were seen with a consequent reduction in the number of double‐labeled neurons. It is suggested that the transient population of SRIF neurons thus revealed plays a role in cortical development.
Spinal origins of preganglionic B and C neurons that innervate paravertebral sympathetic ganglia nine and ten of the bullfrog
Authors: Horn John P. , Stofer William D. 
Published: January 2005

AbstractThese experiments were designed to characterize the distribution, morphology, and number of spinal preganglionic neurons that selectively innervate the B‐ and C‐type sympathetic neurons in paravertebral ganglia 9 and 10 of the bullfrog. For this purpose, horseradish peroxidase (HRP) was applied to the anterior end of the sectioned sympathetic chain between ganglia 8 and 9. Subsequent retrograde axonal transport of the HRP labeled ipsilateral spinal neurons whose cell bodies form a column having rostral and caudal boundaries that are, respectively, just caudal to the level of spinal nerve 4 and midway between the entry zones of spinal nerves 7 and 8. In all segments, the labeled preganglionic somata were found in the lateral half of the spinal gray and slightly dorsal to the central canal; a position analogous to that of the intermediolateral cell column in mammals. Most labeled preganglionic neurons were multipolar in shape, and the cell bodies lying between spinal nerves 4 and 5 were, on average, larger than those found between spinal nerves 7 and 8. In transverse sections that were cut near spinal nerve 5, the axons of preganglionic neurons could be seen to exit the cord through ventral roots.Counts of labeled preganglionic neurons indicate that an average ± S.D. of 338 ± 89 cells innervate ganglia 9 and 10. Selective labeling of preganglionic B neurons, by cutting spinal nerves 7 and 8 central to their rami communicantes at the time of HRP application, revealed an average ± S.D. of 137 ± 31 cells that lie exclusively between spinal nerves 4 and 6. By contrast, selective labeling of preganglionic C neurons, by cutting the sympathetic chain rostral to ganglion 7 at the time of HRP application, revealed an average ± S.D. of 187 ± 77 cells in an adjacent portion of the preganglionic column that is bounded by spinal nerve 6 and by a point midway between spinal nerves 7 and 8. These results thus demonstrate a clear segmental segregation between the preganglionic B and C neurons that innervate ganglia 9 and 10.
Central distribution of trigeminal and upper cervical primary afferents in the rat studied by anterograde transport of horseradish peroxidase conjugated to wheat germ agglutinin
Authors: Pfaller Kristian , Arvidsson Jan 
Published: January 2005

AbstractInjections of WGA‐HRP were made in the rat trigeminal ganglion and C1–3 dorsal root ganglia (DRGs) to study the central projection patterns and their relations to each other. Trigeminal ganglion injections resulted in heavy terminal labeling in all trigeminal sensory nuclei. Prominent labeling was also observed in the solitary tract nucleus and in the medial parts of the dorsal horn at C1–3 levels, but labeling could be followed caudally to the C7 segment. Contralateral trigeminal projections were found in the nucleus caudalis and in the dorsal horn at C1–3 levels. The C1 DRG was found to be inconstant in the rat. When it was present, small amounts of terminal labeling were found in the external cuneate nucleus (ECN) and the central cervical nucleus (CCN). No dorsal horn projections were seen from the C1 DRG. Injections in the C2 DRG resulted in heavy labeling in the ECN, nucleus X, CCN, and dorsal horn, where it was mainly located in lateral areas. Labeling could be followed caudally to the Th 7 segment. C2 DRG projections also appeared in the cuneate nucleus (Cun), in all the trigeminal sensory nuclei, and in the spinal, medial, and lateral vestibular nuclei. A small C2 DRG projection was observed in the ventral cochlear nucleus. C3 DRG injections resulted in heavy labeling in both medial middle and lateral parts of the dorsal horn, in the ECN, and in nucleus X, whereas the labeling in the CCN was somewhat weaker. Smaller projections were seen to trigeminal nuclei, Cun, and the column of Clarke. Comparisons of the central projection fields of trigeminal and upper cervical primary afferents indicated a somatotopic organization but with a certain degree of overlap.
Catecholamine‐containing neurons in Drosophila melanogaster: Distribution and development
Authors: Budnik Vivian , White Kalpana 
Published: January 2005

AbstractThe development of catecholamine‐containing neurons (CA neurons) in the fruit fly Drosophila melanogaster was studied. Glyoxylic‐acid‐induced histofluorescence and antibodies against dopamine and tyrosine hydroxylase were used to describe catecholamine distribution in the larval central nervous system (CNS). The three techniques gave rise to a similar pattern of distribution of putative CA neurons. At all developmental stages CA neurons were distributed widely throughout the CNS but represented only a small fraction of all CNS neurons. Catecholamine‐containing processes were confined to the CNS. The CA neurons are first discerned at about 18 hours of embryonic development. We suggest that these larval CA neurons are maintained throughout the ontogeny of the fly and that the adult CA pattern is composed of embryonic neurons and neurons that differentiate during metamorphosis.
Structural correlates of functionally distinct X‐cells in the lateral geniculate nucleus of the cat
Authors: Humphrey Allen L. , Weller Rosalyn E. 
Published: January 2005

AbstractIn the companion paper (Humphrey and Weller, '88), we demonstrated 2 physiologically different groups of X‐cells (XL and XN) in the A‐laminae of the cat lateral geniculate nucleus. In order to investigate their possible morphological correlates, we iontophoresed horseradish peroxidase intracellularly into physiologically identified XL‐ and XN‐cells and examined their light microscopic appearance.The 11 HRP‐labeled XL‐cells constituted the smallest relay neurons in the A‐laminae, and were similar morphologically. All had small somata (mean soma size = 236 μm2), very thin (< 1.0 μm) axons, few primary dendrites, and narrow, sinuous distal dendrites, which usually formed trees that were oriented perpendicular to laminar borders. The dendrites could be smooth or display beadlike varicosities, hairlike appendages, and/or occasional complex stalked appendages, but their most consistent feature was numerous clusters of grapelike dendritic appendages located at or near dendritic branch points.The 14 labeled XN‐cells were structurally more heterogeneous, and they included relay neurons and interneurons. Eight of 11 XN‐relay cells differed markedly from the XL‐cells. These XN‐cells were multipolar neurons with medium to large somata (mean soma size = 365 μm2), small to medium‐size axons (1.0–2.0 μm), numerous primary dendrites, and straight distal dendrites that formed radially symmetric trees. The dendrites of the cells were largely smooth, except for occasional spines and/or hairs, and they were devoid of grapelike and other complex appendages. The three other XN‐relay neurons had morphologies either similar to XL‐cells or intermediate between XL‐cells and more simple, multipolar XN‐relay cells, but two of these cells had larger somata and axons than most XL‐cells. Finally, three XN‐cells were intrageniculate interneurons, which possessed small somata (mean soma size = 174 μm2), fine sinuous dendrites covered with beadlike varicosities on stalked appendages, and no obvious axon.These results reveal that, despite minor overlap, there are marked structural differences between XL‐ and XN‐cells. Among the relay cells, these differences relate to soma and axon diameter, dendritic orientation, and the presence or absence of grapelike dendritic appendages. Our finding that interneurons were strongly excited at short latencies by spot onset supports the hypothesis (Mastronarde, '87a; Humphrey and Weller, '88) that such interneurons provide the major inhibitory input to XL‐cells, and that this input is important in generating the spot‐induced early dips in XL‐cell discharge.
Anatomical consequences of neonatal infraorbital nerve transection upon the trigeminal ganglion and vibrissa follicle nerves in the adult rat
Authors: Klein Bradley G. , Renehan William E. , Jacquin Mark F. , Rhoades Robert W. 
Published: January 2005

AbstractA large body of experimental literature has demonstrated that neonatal infraorbital nerve damage in rodents produces anatomical and/or functional alterations of the normal whisker representation in central trigeminal structures. Less is known about the organization of primary afferent components of the trigeminal system following this manipulation. Such information provides an important basis for interpreting the central changes observed following damage of infraorbital nerve fibers at birth. We have therefore examined the composition and order of peripheral innervation in the pathway from the trigeminal ganglion to the vibrissa follicles in adult rats subjected to unilateral neonatal infraorbital nerve transectionElectron microscopy was used to determine the number and diameter of myelinated and unmyelinated fibers in vibrissa follicle nerves of these animals. Wheat germ agglutinin‐horseradish peroxidase and fluorescent retrograde tracers were employed to examine the number and diameter, as well as the topographic organization and branching, of ganglion cells innervating the vibrissae in these rats.The data presented below indicate that neonatal infraorbital nerve transection has the following consequences within the adult trigeminal nerve and ganglion: (1) an alteration of the gross morphology of vibrissal nerves, (2) a significant reduction in the average number (85.4%) and diameter (32.6%) of myelinated, but not unmyelinated, follicle nerve axons, (3) a significant decrease in the average number (36.8%) of trigeminal ganglion cells innervating vibrissa follicles, (4) no significant change in the distribution of ganglion cell diameters, (5) an increase in peripheral branching (1.8‐fold) of these ganglion cell axons, and (6) an alteration of somatotopic order within the trigeminal ganglion.Taken together, these data indicate that neonatal infraorbital nerve transection produces a profound reorganization of the primary afferent component of the trigeminal neuraxis.
Morphological and electrophysiological identification of gigantocellular tegmental field neurons with descending projections in the cat: I. Pons
Authors: Mitani Akira , Ito Keihachiro , Mitani Yuko , McCarley Robert W. 
Published: January 2005

AbstractTwo different descending projections from the pontine gigantocellular tegmental field (PFTG) were denned by the use of intracellular recording and intracellular horseradish peroxidase (HRP) techniques in the cat. Type I neurons (reticulospinal neurons) had antidromic spike potentials produced by stimulation of the ipsilateral medial longitudinal fasciculus (MLF) and sent axons to the ipsilateral MLF. Most type I neurons had large ellipsoidpolygonal somata (mean, 59.7 μm), thick axons (average diameter, 3.33 μm), and slightly oblate large dendritic fields. The mean anteroposterior extent of the dendritic field was 1,492 μm, the mean mediolateral extent was 1,784 μm, and the mean dorsoventral extent was 1,562 μm. There were no type I neurons with axon collaterals. In contrast, type II neurons (reticuloreticular neurons) had antidromic spike potentials produced by stimulation of the bulbar reticular formation (BRF) and sent axons directly to the BRF. In comparison with type I neurons, most type II neurons had smaller ellipsoid‐polygonal somata (mean, 40.2 μm), thinner axons (average diameter, 2.32 μm), and smaller, slightly oblate dendritic fields. The mean anteroposterior extent of the dendritic field was 1,264 μm; the mean mediolateral extent was 1,511 μm; and the mean dorsoventral extent was 1,226 μm. Also in contrast to type I neurons, 36% of type II neurons had axon collaterals.
Descending projections from the gigantocellular tegmental field in the cat: Cells of origin and their brainstem and spinal cord trajectories
Authors: Mitani Akira , Ito Keihachiro , Mitani Yuko , McCarley Robert W. 
Published: January 2005

AbstractThe trajectories and the cells of origin of the pontobulbar gigantocellular tegmental field descending pathways were studied in the cat using anterograde WGA‐HRP and retrograde HRP techniques. Four main descending pathways and cells of origin were delineated: (1) Predominantly large neurons in the pontine gigantocellular tegmental field (average soma diameter = 43.4 μm) and rostral bulbar gigantocellular tegmental field (41.3 μm) gave rise to reticulospinal fibers descending in the ipsilateral medial longitudinal fasciculus and ventral funiculus and distributed in laminae V‐X with an ipsilateral predominance. These were primarily large‐diameter fibers. (2) Predominantly large neurons (46.9 μm) in the bulbar gigantocellular tegmental field gave rise to reticulospinal fibers descending in the contralateral medial longitudinal fasciculus and ventral funiculus. These were mainly large‐diameter fibers. (3) Neurons of predominantly medium size (29.5 μm) in the pontine gigantocellular tegmental field gave rise to reticuloreticular fibers descending directly to and distributed bilaterally in the bulbar reticular formation. These were small‐diameter fibers. (4) Neurons of predominantly medium size (28.9 μm) in the bulbar gigantocellular tegmental field gave rise to reticulospinal fibers descending in the ipsilateral reticular formation and lateral funiculus. These were small‐diameter fibers.
Monosynaptic transmission of respiratory drive to phrenic motoneurons from brainstem bulbospinal neurons in rats
Authors: Ellenberger Howard H. , Feldman Jack L. 
Published: January 2005

AbstractThe termination patterns in the rat phrenic nucleus of neurons within two respiratory cell groups of the ventrolateral medulla (Bötzinger Complex and the rostral ventral respiratory group) were determined. The plant lectin, Phaseolus vulgaris leuco‐agglutinin, was used as an anterograde tracer to label presynaptic processes of bulbospinal neurons, and horseradish peroxidase was used simultaneously to label phrenic motoneurons. Labeled bulbospinal axons ended with dense terminal arborizations within the phrenic cell column and on radial phrenic motoneuron dendrite bundles, which represented the exclusive site of termination of Bötzinger Complex and rostral ventral respiratory group neurons in the lower cervical spinal cord. Terminals of these descending axons formed presumptive synaptic contacts within longitudinal and radial dendrite bundles, and on the cell somata of phrenic motoneurons.
Development of the dopaminergic innervation in the prefrontal cortex of the rat
Authors: Kalsbeek A. , Voorn P. , Buijs R. M. , Pool C. W. , Uylings H. B. M. 
Published: January 2005

AbstractThe pre‐ and postnatal development of the dopaminergic innervation in the prefrontal cortex (PFC) of the rat is described from embryonic day 14 through postnatal day 90. By embryonic day 15 the dopamine (DA)‐containing fibers reach the anlage of the lateral neocortex; 2 days later the first fibers have reached the subplate of the future prefrontal cortex. The process of entering the cortical plate starts just before birth. Prenatally, some dopaminergic fibers can be observed in the marginal zone of both the lateral and the medial wall of the hemisphere. Within 48 hours after birth a large number of dopaminergic fibers can be observed in the marginal zone, i.e., the future layer I, in some subareas of the PFC. A transient appearance of DA‐positive fibers is noticed in the late embryonic and early postnatal periods especially in the marginal zone and possibly in the superficial layers of the pregenual cingulate cortex. Changes in the morphology of DA fibers at P4 suggest that the actual DA innervation starts at this age. From postnatal day 6 the different subareas of the PFC can be recognized according to the characteristics of the topographical distribution of the dopaminergic fibers. Until postnatal day 60 the density of the dopaminergic fibers continues to increase. No difference in density and topography was observed between postnatal days 60 and 90.
Autoradiographic studies of cerebellar histogenesis in the premetamorphic bullfrog tadpole: II. Formation of the interauricular granular band
Authors: Uray Nandor J. , Gona Amos G. , Hauser Kurt F. 
Published: January 2005

AbstractThis study examines the origin of cells in the interauricular granular band (iagb) in the cerebellum of the frog tadpole during early stages of development by means of histological and autoradiographic methods.Premetamorphic bullfrog tadpoles were exposed to multiple doses of 3H‐thymidine (10 μCi/g body weight per exposure) at developmental stages ranging from 1 week to 1 year and were killed at either 6 or 12 months of age. The autoradiographic data were examined to determine the time when cells of the iagb were generated.Our findings show that initial generation of iagb cells begins at week 3 and that a peak in the formation of postmitotic neurons is reached at the age of 10 weeks. This is followed by other peaks of cell generation at the ages of 16 weeks, 10 months, and 11.5 months. The generation cycles of iagb cells are interrupted by periods of quiescence when label cannot be detected in any of the cells. These quiescent periods occur at the ages of 20–26 weeks, 7 months, and 12 months. These findings indicate that cells of the iagb are generated in a cyclical manner over the entire 1‐year period which was studied. Comparison of our present data on iagb cell formation with the generation of cells in the EGL shows that the production of these two groups of cells is overlapping, but cells of the iagb begin and cease production before those of the EGL. On the basis of our findings we propose that the cells of the iagb and the EGL belong in separate cell groups which are generated by distinct subpopulations of germinal cells in the neuroepithelial cap.
Do axons grow during adulthood? A study of caliber and microtubules of sural nerve axons in young, mature, and aging rats
Authors: Saitua Francisco , Alvarez Jaime 
Published: January 2005

AbstractCalibers and microtubules of sural nerve axons were studied in young (6‐week‐old), mature (14‐week‐old), and aging (2‐year‐old) rats. The mean cross‐sectional area of nonmedullated fibers was about 0.50 μm2 (range: 0.47–0.52) in the three age groups. Their caliber spectra were also similar. In contrast, myelinated axons grew from 6.6 to 16.7 μm2 between the sixth and 14th week of age. The increase of cross‐sectional area was greater, the greater the initial caliber of axon (range 44–154%). No further change of caliber was observed in the aging rat. The cross‐sectional area of nerve allotted per myelinated fiber was 42, 66, and 97 μm2 in young, mature, and aging rats, respectively. The fraction of nerve tissue occupied by the axoplasm, though, did not change substantially; it was 20, 28, and 21%, respectively. The microtubules density of 3‐μm3 myelinated axons had a general average of 21 microtubules μm2. Differences between groups were not significant. In nonmedullated fibers, the microtubular density decreased as the size of the axon increased. No differences were observed between age groups. We conclude that nonmedullated fibers of the sural nerve stop growing before the sixth week whereas myelinated fibers keep growing until the 14th week of age. The correlation between microtubular content and axonal caliber is a lifelong feature of axons.