bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autoradiographic localization of newly synthesized octopamine to retinal efferents in the Limulus visual system
Authors: Evans Judith A. , Chamberlain Steven C. , Battelle Barbara‐Anne 
Published: May 2005

AbstractThe biogenic amine octopamine is synthesized from both tyrosine and tyramine in the lateral, median, and ventral eyes of Limulus. The auto‐radiographic studies presented here were designed to locate the sites of octopamine synthesis in the ventral and lateral eyes. We found that efferent fibers, which project to ventral and lateral eyes from the central nervous system, became intesely and selectively labeled during in vitro incubationswith 3H‐tyramine. In the ventral eye, more than 95% of the efferent fibers were labeled. Results of biochemical analyses suggested that most of the radioactive substance within these efferent fibers was newly synthesized octopamine.The selective labeline of efferent fibers during incubation with 3H‐tyramine was used as anatomical tool to study me number ana distribution of efferent fibers within the ventral eye. Light microscopic (LM) reconstructions of the distribution of label in serial longitudinal sections through ventral optic nerves together with electron microscopic (EM) au‐toradiographic analyses revealed between 70 and 200 efferent axons. The results of these studies and of reconstructions of efferent innervation to photoreceptor somata suggest that each ventral photoreceptor cell or each small cluster of cells is innervated by a separate efferent fiber. Both LM reconstructions and EM analyses showed that efferent fibers ramify extensively and specifically in and near the internal rhabdom of ventral photo‐receptor cells.In EM autoradiographs of lateral eyes incubated with 3H‐tyramine, the silver grains that were located over ommatidia were concentrated exclusively over efferent fibers. All of these efferent fibers, which lay near rhab‐doms and in partitions between retinular cells, were labeled.The results of our present studies support our hypothesis that octopamine is a neurotransmitter in Limulus retinal efferent fibers. This amine may modulate the biochemistry and physiology of ventral photoreceptor cells and may mediate many of the known effects of circadian efferent innervation to the lateral eye.
The development and postnatal organization of motor nuclei in the rat thoracic spinal cord
Authors: Smithm Carolyn L. , Hollyday Margaret 
Published: May 2005

AbstractThe topographic organization of the motor nuclei supplying individual thoracic muscles in postnatal rats was investigated by horseradish peroxi‐dase (HRP) labelling from the periphery. To determine whether aspects of the same organization are apparent at early developmental stages, we used HRP to label neurons contributing axons to the two primary rami of thoracic nerves in rat fetuses ranging in age from the 13th day of gestation to birth. This developmental period includes stages during which peripheral nerves and muscles are forming. The results show that motoneurons in the appropriate positions in the ventral horn have axons in each primary ramus even at stages prior to the innervation of muscle. However, in fetuses at certain developmental stages, there are also neurons located outside the motor nuclei which send axons into the peripheral nerves.
Spastic Mutant axolotl: Identification of a phenocopy pathway with implications for the control of axolotl swimming by the vestibulocerebellum
Authors: Elbert Oliver E. , Ide Charles F. , Duda Marija , Hunt R. K. 
Published: May 2005

AbstractThe spastic mutant axolotl shows abnormal swimming behavior, which includes a preponderance of “embryonic” swimming elements (coils) versus mature swimming elements (sinusoids) and a failure to entrain sinusoids into a prolonged swimming sequence. The mutant also shows anatomical disorganization in the area acousticolateralis and cerebellar auricle, but it is unclear (1) to what extent the behavioral abnormalities are traceable to the vestibulocerebellar defect or (2) how the vestibulocerebellar pathway modulates swimming behavior in the normal axolotl. We have performed quantitative cine analysis of electric shock‐induced swimming bouts in normal axolotls, spastic mutants, and a variety of neurosurgically altered wild‐type axolotls. We scored the incidence of coil elements (25% in controls, 70‐90% in spastics) versus sinusoid elements, as well as length distributions of coil‐free intervals (short to long trains of sinusoidal swimming) and of sinusoid‐free intervals (of brief to prolonged coiling). We found that bilateral VHIth nerve lesions or surgical undercutting of the cerebellar auricle in wild‐type axolotls almost exactly reproduced the behavioral deficit seen in spastic (75‐81% coils, loss of long sinusoid trains, and appearance of prolonged coiling intervals at least some of which coupled several coils into trains of thrashing behavior). By contrast, neither complete transection of the CNS at low midbrain levels nor section of cranial nerves V, VII, or X (lateral line) resulted in an increased incidence of coil elements beyond 26% nor significantly altered the length distributions of S‐intervals and C‐intervals. Nor did any of the latter lesions disrupt the spasticlike swimming patterns of axolots already subjected to auricle or VIIIth nerve lesions. Our data suggest that spastic behavior is attributable to some defect(s) in the vestibulocerebellar pathway, and that this pathway plays a rather subtle role in the control of swimming that involves, among other features, the selection and entrainment of mature swimming elements over embryonic ones.
Morphology of C‐laminae neurons in the dorsal lateral geniculate nucleus of the cat: A Golgi impregnation study
Authors: Hitchcock Peter F. , Hickey T. L. 
Published: May 2005

AbstractOn the basis of their dendritic morphology, neurons in the C‐laminae of the cat's dorsal lateral geniculate nucleus (dLGN) have been divided into five groups. These groupings are based on previous descriptions of the neuronal types present in the dLGN of the cat (Guillery, '66; Famiglietti, 70; Updyke, 79). Class 1, 2, 3, and 5 neurons in the C‐laminae are essentially identical to their counterparts in the A‐laminae, with one exception. The dendritic orientation of class 2, 3, and 5 neurons found in the C‐laminae is, for the most part, parallel to the laminar borders. In the A‐laminae, class 2 and 5 neurons show no preference in their dendritic orientation and class 3 neuron dendritic orientation is predominantly perpendicular to the laminar borders.Class 4 neurons are found in all C‐laminae and make up the bulk of the impregnated neurons. They are morphologically distinct from A‐laminae neurons but exhibit a broad range of structural characteristics.
Afferent connections of the perirhinal cortex in the rat
Authors: Deacon Terrence W. , Eichenbaum Howard , Rosenberg Paul , Eckmann Kenneth W. 
Published: May 2005

AbstractConnections of the perirhinal cortex in the.rat brain were studied using anterograde (3H‐proline/leucine) and retrograde (horseradish peroxidase) tracers. The perirhinal cortex receives major projections from medial precen‐tral, anterior cingulate, prelimbic, ventral lateral orbital, ventral and posterior agranular insular, temporal, superior and granular parietal, lateral occipital, agranular retrosplenial, and ectorhinal cortices, and from the pre‐subiculum, subiculum, and diagonal band of Broca. Rostral neocortical areas project predominantly to rostral perirhinal regions while more caudal neocortical and subicular areas project predominantly to caudal perirhinal regions.Terminal fields are further segregated within perirhinal cortex to either the dorsal or ventral banks of the rhinal sulcus. All afferents from frontal areas terminate predominantly in the deep layers of its ventral bank; afferents from temporal, parietal, and lateral occipital areas terminate predominantly in the deep and superficial layers along its dorsal bank; and afferents from ectorhinal cortex terminate in a column within its dorsal bank.Cortical cells which project to perirhinal areas are found predominantly in layer II and the superficial part of layer III. However, ventrolateral orbital, parietal, and lateral occipital cortex projections originate predominantly from layer V.Perirhinal areas also receive afferents from the nucleus reuniens of the thalamus, lateral nucleus of the amygdala, claustrum, supramammillary nuclei, and the dorsal raphe nuclei.
Afferent influences on brainstem auditory nuclei of the chicken: N. laminaris dendritic length following monaural conductive hearing loss
Authors: Smith Zaid D.J. , Gray Lincoln , Rubel Edwi W 
Published: May 2005

AbstractThe influence of monaural acoustic deprivation on the size of dendrites in n. laminaris in the chick was examined. Chicks were raised in a controlled acoustic environment with one ear occluded from 2 days prior to hatching until 25 days after hatching by an earplug which provided a conductive hearing loss of approximately 40 dB across the audible frequency range. Each n. laminaris cell receives spatially segregated binaural excitatory innervation; one dendritic field received input from the plugged ear while the other received input from the normal ear. This arrangement allowed comparison of the size (length) of the “deprived” dendrites and the “nondeprived” dendrites for each cell. The tonotopic organization of n. laminaris allowed these comparisons to be made as a function of the frequency organization of the nucleus.We observed systematic changes in dendritic size which differed as a function of the tonotopic position of the neurons. In high‐frequency regions the dendrites receiving information from the deprived ear were shorter than those receiving input from the normal ear. Unexpectedly, cells responsive to low frequencies showed the opposite result; the dendrites innervated from the deprived ear were longer than those responsive to the nondeprived ear. These results suggests that a relatively flat conductive hearing loss may cause nonuniform changes in activity impinging on high‐ and low‐frequency areas of the auditory system.
Anatomical and physiological studies of the gray matter surrounding the spinal cord central canal
Authors: Nahin Richard L. , Madsen Anne M. , Giesler Glenn J. 
Published: May 2005

AbstractRecent histochemical evidence suggests that neurons in the gray matter surrounding the central canal may play a role in nociception. We attempted to evaluate this possibility by studying the response properties and ascending projections of these cells in the rat.In the first series of experiments, the ascending projections of neurons around the central canal were studied by the method of retrograde transport of horseradish peroxidase (HRP). Predominantly contralateral labeling of neurons around the central canal appeared after HRP injections into the paramedian medullary or pontine reticular formation in intact or cerebellec‐tomized animals. Far fewer cells were labeled by injections into the lateral medulla and/or pons. A small number of cells was retrogradely labeled by HRP injections into the vermal and ntermediate regions of the cerebellum or the periaqueductal gray matter. Injections into other brainstem areas outside of the reticular formation also failed to label large numbers of neurons around the central canal.In a second set of experiments, we recorded extracellular unitary activity from the lumbar enlargement in spinalized, decerebrate, unanesthetized rats. Thirteen units were functionally characterized and histologically localized within 300 μ of the central canal. All of the units identified responded exclusively to noxious stimuli applied within highly circumscrioed receptive fields.Thus, neurons around the central canal contribute strongly to long ascending spinal cord projections. Physiologically, neurons found within this region are reminiscent of the noxious‐specific cells in the outer most layers of the dorsal horn.
The percentage of interneurons in the dorsal lateral geniculate nucleus of the cat and observations on several variables that affect the sensitivity of horseradish peroxidase as a retrograde marker
Authors: Weber Arthur J. , Kalil Ronald E. 
Published: May 2005

AbstractTen cats ranging in age from 4 weeks postnatal to adult received large bilateral injections of horseradish peroxidase (HRP) into cortical areas 17 and 18. In one cat additional unilateral injections of HRP were made into the lateral suprasylvian visual area (PMLS). The purpose of these injections was to label relay cells in lamina A of the dorsal lateral geniculate nucleus (LGN), in order to distinguish them from neurons that could not be labeled retrogradely.Several factors thought to influence the effectiveness of HRP as a retrograde marker were varied in an effort to label as many relay cells as possible. These factors included the (1) rate and duration of HRP injections; (2) volume and concentration of HRP injected; (3) addition of L‐α‐lysophospha‐tidylcholine or dimethyl sulfoxide to the injected HRP; and (4) aldehydes and buffers used for fixation. In all experiments DAB (3,3′‐diaminobenzidine tetrahydrochloride) was used as the chromogen, either alone or with the addition of cobalt chloride, nickel, and cobalt salts, or cobalt‐glucose oxidase. In l‐μ plastic sections, the influence of each of the above factors and DAB methods was determined by measuring the percentage of unlabeled neurons and the cytoplasmic HRP grain density of cells that were labeled.Our results show that approximately 22% of the neurons in lamina A of the LGN remain unlabeled following injections of HRP into areas 17 and 18 alone or combined with injections into PMLS. The percentage of unlabeled cells is similar at each of the ages that we studied and is not affected significantly by any of the factors that were varied or DAB methods that were used.Cross‐sectional area measurements show that unlabeled cells tend to be among the smallest neurons in lamina A. Regardless of age, the mean size of labeled neurons was about twice that of unlabeled cells. However, we found only a weak correlation between the size of a labeled cell and the cytoplasmic density of HRP grains. Thus it is unlikely that small cell body size alone can account for tne unlabeled cells in lamina A, since small neurons can be as effective in transporting HHP retrogradely as large neurons.We therefore conclude that there is a distinct population of small neurons in lamina A of the LGN that do not project to cortex. Although we cannot rule out the possibility that these cells project subcortically, we believe that it is reasonable to regard them as interneurons.
Axonal patterns and topography of short‐axon neurons in visual areas 17, 18, and 19 of the cat
Authors: Meyer Gundela 
Published: May 2005

AbstractIn a Golgi study of short‐axon cells in areas 17, 18, and 19 of the adult cat, 21 main axonal arborization patterns are distinguished and related to laminar position and dendritic morphology. Multipolar neurons exclusive to layer 2/3 exhibit the greatest diversity of axons: These may be arranged in a local tuft, a single descending stem with recurrent collaterals, a columnar descending plexus, horsetaillike bundles, a dense intralaminar plexus, or a varicose local arbor. Multipolar cells of layers 2–5 may have local basket or chandelier axons or a neurogliform axonal plexus, and axons in layer 4 may branch into a columnar basket plexus. Two types of multipolar cells are described in layers 5 and 6. Also, neurons with a bitufted dendritic tree have different axonal patterns: cone‐shaped axons, arcade axons, profuse ascending plexuses, and columnar or diffuse ascending and descending arbors. The axons of bitufted cells in layer 6 ascend or form a local tuft. Finally, giant bitufted cells with local axons, bitufted or multipolar cells with horizontal axons, and bipolar cells are described. The neuronal types established on the basis of their axonal arbor are compared to previous classifications of cortical neurons.The location of neurons thus classified has been recorded and evaluated. Most cells show no topographical specificity and occur indistinctly in the three visual areas, while two types are exclusive to area 17. Horsetail neurons accumulate at the 17/18 and 18/19 borders. Multipolar cells of layer 2/3 with a dense intralaminar plexus and chandelier cells are concentrated in the region where the central visual field is represented.
Relationship between preferred orientation and receptive field position of neurons in cat striate cortex
Authors: Leventhal Audie G. 
Published: May 2005

AbstractIt has been known for two decades that neurons in mammalian visual cortex respond selectively to stimuli falling on the retina at a particular angular orientation (Hubel and Wiesel, '62). Recent evidence suggests that most cat retinal ganglion cells (Levick and Thibos, '82) and relay cells (Vidyasagar and Urbas, '82) in the cat's dorsal lateral geniculate nucleus are also orientation selective. In the retina there is a systematic relationship between receptive field position (polar angle) and preferred orientation. Outside of the area centralis, most retinal ganglion cells have oriented dendritic fields (Leventhal and Schall, '83) and respond best to stimuli oriented radially, i.e., oriented parallel to the line connecting their receptive fields to the area centralis (Levick and Thibos, '82). This relationship is strongest close to the horizontal meridian (the visual streak) of the retina (Leventhal and Schall, '83).To determine if a relationship between preferred orientation and polar angle exists in visual cortex, the preferred orientations and receptive field positions of 768 striate cortical neurons were studied. As in the retina, a systematic relationship exists between preferred orientation and visual field position in area 17. In parts of striate cortex 15–80° from the area centralis projection there is a strong tendency for cells to respond best to lines oriented radially. In regions 4–15° from the area centralis projection this relationship appears weaker. In regions subserving the central 4° of visual angle no such relationship exists. Throughout area 17 the relationship between preferred orientation and polar angle is strongest in regions subserving the horizontal meridian.It is suggested that the systematic relationship between preferred orientation and polar angle which begins in the retina provides an intrinsic framework for the organized arrangement of orientation “columns” in visual cortex (Hubel and Wiesel, '63). This relationship may also be responsible for the “oblique effect” as well as the visual system's preferential response to radially oriented gratings (Rovamo et al.,'82).
Time course of morphological differentiation of cat retinal ganglion cells: Influences on soma size
Authors: Rapaport David H. , Stone Jonathan 
Published: May 2005

AbstractWe have examined the growth of ganglion cell somas during development of the cat's retina. Until approximately E (embryonic day) 50, ganglion cell somas show no sign of the several variations in their size apparent in the adult. At about E50, the somas begin to accumulate granular cytoplasm. The accumulation proceeds first among area centralis cells which, for a few days, are the largest ganglion cells in the retina (whereas in the adult they are the smallest). By E57 three of the adult soma size trends have become apparent: the differentiation of soma size related to functional class, the nasal‐temporal difference in soma size, and the small mean size of somas in the visual streak. The early appearance of these trends in soma size suggests that individual cells may be intrinsically programmed to develop as cells of a particular class, such as alpha‐, beta‐, or gamma‐cells, even before their morphological differentiation begins. A fourth trend in soma size, the centro‐peripheral difference, appears only after an initial period of ganglion cell growth; the small size of ganglion cells at the area centralis seems to be determined, at least partly, by a local “environmental” factor, the crowding of ganglion cells.
The olivocerebellar projection to the uvula in the mouse
Authors: Eisenman Leonard M. , Sieger David D. , Blatt Gene J. 
Published: May 2005

AbstractThe organization of the olivocerebellar projection in the mouse was studied with the use of microinjections of horseradish peroxidase (HRP) or HRP conjugated to wheat germ agglutinin (WGA‐HRP). Injections were made in medial, intermediate, and lateral sites along the width of the uvula. The purpose of this investigation was to determine the subnuclear origin of olivary afferents to different mediolateral regions of the uvula. Injections made in or adjacent to the midline of the uvula resulted in the retrograde labeling of cells, bilaterally in the caudal portion of the medial accessory olive (MAO). These labeled cells were located primarily in subnucleus C and nucleus β of the MAO. Injections into the intermediate part of the uvula resulted in the labeling of cells in the caudal MAO (primarily nucleus β), the dorsomedial cell column (dmcc), and a few cells in the ventral lamella of the principal olive (vPO). Laterally placed injections produced labeling of cells in dmcc and the vPO. These results are discussed in reference to the parasagittal organization of olivary afferents to the cerebellar cortex in the mouse (Beyerl et al., '82) and the organization of afferents to the involved regions of the inferior olivary (IO) complex. It is suggested that these parasagittal zones in the uvula may play different roles in the control of eye movements.
Developmental changes in the relationship between type 2 synapses and spiny neurons in the monkey visual cortex
Authors: Mates Sharon L. , Lund Jennifer S. 
Published: May 2005

AbstractThis study continues an exploration of synaptic development in the primary visual cortex of the monkey (Macaca nemestrina). In a prior study (Mates and Lund, '83a), we observed that type 2 synapses on the cell bodies of spiny stellate neurons of lamina 4C appeared not only to increase in number during early postnatal development but also subsequently decreased during maturation. Using quantitative, stereological electron microscopic methods, we examined the maturation of this synapse population from embryonic day 159 to adult, on spiny stellate neurons of 4Cα and β and, for comparison, on pyramidal neurons in upper and lower lamina 6. Tissue was also taken for comparison from two animals reared to 8 weeks of age with binocular eyelid closure from birth. We confirmed that a marked increase and subsequent decrease occurred in this somal type 2 synapse population on both neuron populations. However, due to the infrequency of the smooth dendritic neurons (approximately 5% of the neuron population) giving rise to the type 2 contacts, and due to expansion of the neuropil during maturation increasing intercell distances against constant volume of the type 2 axon arbors, it is concluded that the decrease in, type 2 somal synapses may represent a redistribution to dendrites rather than loss from the neuropil. Cells of lamina 4Cβ (receiving input from the parvocellular lateral geniculate nucleus‐LGN) show a slower initial accumulation of type 2 contacts compared to neurons of lamina 4Cα (receiving input from magnocellular LGN), or to pyramidal neurons of lamina 6. The type 2 synapse population of the 4Cβ neurons also showed no reduction in the animals visually deprived to 8 weeks of age, unlike the populations of type 2 synapses in 4Cα and 6, which were fewer than normal.