bluuebunny/crossref_metadata_2025_split huggingface dataset:
The organization of projections from the olfactory bulb to the piriform cortex and olfactory tubercle in the rat
Authors: Scott John W. , McBride Russell L. , Schneider Stephen P. 
Published: January 2005

AbstractThe organization of the projection of olfactory bulb output cells was studied in the rat by injection of horseradish peroxidase (HRP) into the piriform cortex or olfactory tubercle. We made single HRP injections into small cuts in the fiber layer of the projection areas in order to enhance uptake by axons and to confine the region of HRP uptake. Following most of these injections, HRP‐labeled axons could be traced in discrete fascicles through the fiber layer of the cortex or tubercle. These observations indicate that axons innervating the piriform cortex do not emit many long collaterals after they leave the lateral olfactory bulb, but there were regions of greater density of labeled that differed in the various brains. The differences among the distributions of labeled mitral and tufted cells were analyzed statistically in 39 brains to test whether they varied systematically with injection site. In these analyses, the olfactory bulb was divided into 30 standard regions, and the labeled cells in each regions were counted.The distributions of labeled cells were similar for brains where injections were made into similar regions of the piriform cortex. The variations in density of labeled cells of the dorsal and anterior regions of the olfactory bulb were most strongly correlated with the positions of cortical injections. In contrast, the posterior medial regions of the bulb were heavily labeled after almost all injections. The ventral portions of the olfactory bulb were most heavily labeled after injections into the olfactory tubercle.
Physilogy and morphology of substantia gelatinosa neurons intracellularly stained with horserdish peroxidase
Authors: Bennett Gary J. , Abdelmoumene Mohammed , Hayashi Haruhide , Dubner Ronald 
Published: January 2005

AbstractNeurons in Rexed's layer II were physiologically characterized with natural and electrical stimuli applied to their cutaneous receptive field. The neurons were then intracellularly stained with horseradish peroxidase. Three general patterns of physiological responses were found Nociceptive specific neurons did not respond to gentle mechanical stimulation. Most responded exclusively to tissue‐damaging stimuli. Some also responded to moderately heavy pressure, but these responded to noxious stimuli with an increased discharge frequency. Wide dynamic range neurons responded to both gentle mechanical stimulation and to tissue‐damaging stimulation. Low‐threshold mechanoreceptive neurons responded only to gentle mechanical stimulation. Some of the low‐threshold mechanoreceptive neurons were innervated by primary afferents with unmyelinated axons. Excepting those low‐threshold mechanoreceptive neurons with input form unmyelinated afferents, the patterns of primary afferent innervation of layer II neurons were similar to the patterns innervation that gave been found for neurons in layers I and IV‐V.All nut 2 of the 22 neurons that we found were recognized as being of two general morphological types. Stalked cells had their perikarya situated along the superficial border of layer II. Most of their dendrites traveled ventrally while spreading out rostrocaudally. This gave their dendritic arbors a fan‐like shape. Stalked cell axons arborized largely in layer I. Islet cell perikarya were found throughout layer II. Most of their dendrites traveled rostrocaudally. Their dendritic arbors were shaped like cylinders with their long axes parallel to the long axis of the spinal cord. Islet cell axons arborized in the immediate vicinity of their dendtritic territories, within layer II.Stalked cells and those islet cells whose dendritic arbors were largely contained within the superficial one‐third of layer II (layer IIa) were either nociceptive specific or wide dynamic range neurons. The islet cells whose dendritic arbors were largely within the deeper two‐thirds of layer II (layer IIb) were all low‐threshold mechanoreceptive neurons. These observations suggest that layers IIa and IIb have different functional roles and that stalked cells and islet cells are separate and distinct components of the neural circuitry of the superficial dorsal horn.
Development of the brain stem in the rat. IV. Thymidine‐radiographic study of the time of orgin of neurons in the pontine region
Authors: Altman Joseph , Bayer Shirley A. 
Published: January 2005

AbstractGroups of pregnant rats ware injected with two successive daily doses of 3H‐thymidine form gestational day 12 and 13 (E12 + 13) until the day before parturition (E21 + 22) in order to label in their embryos the proliferating precursors of neurons. At 60 days of age the proportion of neurons generated (or no longer labeled) on specific embryonic days was determined quantitatively in 14 nuclei of the pontine region. Peak production time of neurons of the trigeminal mesencephalic nucleus was on day E11 or earlier, with a small proportion generated on day E12. Peak production time of the trigeminal motor neurons was on day E12, with a small proportion produced earlier. Neurons of the principal sensory nucleus were generated between days E13 and E16, with a peak on day E14; the late‐produced neurons tended to belong to a class of intermediate and large cells. The bulk of the neurons of the supratrigeminal and infratrigeminal nuclei arose on day E15 and E16.Neurons of the locus coeruleus are produced mostly on day E12, with about 20% of the cells arising on day E13. The bulk of the neurons of the dorsal tegmental nucleus (Gudden's) are produced between days E13 and E15, whereas most of the neurons of the deep (ventral) tegmental nucleus are produced on day E15. A dorsal‐to‐caudal gradient was also obtained between the dorsal and vental nuclei of the lateral lemniscus, the neurons of the former being generated between days E12 and E15; the latter, between days E13 and E17. The neurons of both the pars lateralis and the pars medialis of the parabrachial nucleus were produced simultaneously between days E13 and E15, with a peak on day E13. the heterogeneous collection of neurons of the pontine paramedial reticular formation was produced from day E11 (or earlier) until day E15. Finally, the neurons of the raphe pontis parvicellularis were generated at an even rate between days E13 and E15, whereas the bulk of the neurons of the raphe pontis magnocellularis were produced on days E15 and E16.On the basis of datings obtained for 9 subdivisions of the entire brain stem trigeminal complex, hypotheses were offered of the cytogenetic components of the system. The sequence of neuron production in the dorsal and deep tegmental nuclei was related to their connections with divisions of the mammillary and habenular nuclei on a “first come‐first serve” basis.
Projections of the cerebellar and dorsal column nuclei upon the thalamus of the rhesus monkey
Authors: Kalil Katherine 
Published: January 2005

AbstractProjections from the cerebellar and dorsal column nuclei to the midbrain and thalamus of the rhesus monkey were traced with anterograde autoradiographic techniques, or, in a few cases, with the Fink‐Heimer method.The cerebellar nuclei give rise to a massive projection to the contralateral midbrain and thalamus via the ascending limb of the superior cerebellar peduncle. Cerebellar efferent fibers terminate contralaterally in both divisions of the red nucleus, and bilaterally in the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, the oculomotor nucleus, and the central gray.All the deep cerebellar nuclei project upon a broad area of the contralateral ventral thalamus as well as certain intralaminar nuclei. Corresponding ipsilateral thalamic terminations are sparse. The topograpic organization of cerebellothalamic fibers does not correspond to individual cerebellar nuclei or to cytoarchitectonic divisions of the ventral thalamic nuclei. Rather there are longitudinally oriented strips of terminal labeling which extend through all divisions of the ventral lateral nucleus, i.e., the VLps, the VLc, the VLo, as well as nucleus X, the oral division of the ventral posterolateral nucleus (VPLo), the central lateral nucleus (CL), and the most caudal region of the ventral anterior nucleus (VA). The topography of the cerebellothalamic fibers is arranged in a mediolateral pattern with fibers originating from anterior zones of the dentate and interpositus ending most laterally and those from posterior dentate and interpositus terminating most medially. The fastigial contribution is relatively sparse.The longitudinal strips of terminal labeling in the ventral thalamic nuclei are made up of still smaller terminal units consisting of disk‐like aggregates of silver grains separated from one another by grain‐free spaces.The dorsal column nuclei terminate primarily in the contralateral caudal division of the VPL (VPLc) and never extend rostrally into VPLo.These results demonstrate a segregation of cerebellar and dorsal columnar inputs to motor and sensory regions of the thalamus, respectively. Since these regions are separate and discrete in their cortical associations as well (Kalil, 1976), it seems unlikely that fast afferent pathways relaying to motor cortex (Lemon and Porter, 1976) could arise from the dorsal column nuclei.
Cortical and spinal somatosensory input to the superior colliculus in the golden hamster: An anatomical and electrophysiological study
Authors: Rhoades Robert W. 
Published: January 2005

AbstractThe horseradish peroxidase technique was used to identify the sources of somatosensory afferent fibers to the hamster's superior colliculus. These experiments demonstrated that the tectum receives axons from pyramidal cells in layer V of the ipsilateral sensorimotor cortex, contralateral lamina IV of all levels of the spinal cord, the contralateral dorsal column nuclei, lateral cervical nucleus, internal basilar nucleus, and nucleus of the spinal trigeminal tract.Electrical stimulation of the spinal cord coupled with extracellular single unit recordings concentrated, for the most part, in the posterior portion of the tectum revealed that such stimuli activated approximately 40% of the cells tested. Almost of these units were isolated ventral to the stratum opticum and 86% were responsive only to somatosensory stimulation. Analysis of the latencies of collicular responses obtained with two point spinal stimulation in intact hamsters and in animals subjected to somatosensory cortical and/or spinal damage indicated that the initial impulse elicited from most collicular cells was mediated by a polysynaptic pathways(s) which probably synapses in the dorsal column, lateral cervical, and/or internal basilar nuclei.Damage to the dorsal spinal cord and/or somatosensory cortex altered neither the incidence nor the response characteristics of spinally driven collicular neurons. This indicated that most somatosensory collicular cells also received input from the spinotectal fibers which travel in the ventrolateral quadrant.Electrical stimulation of somatosensory cortex activated about 20% of the cells tested in the ipsilateral superior colliculus. If cortical and spinal stimulation were delivered with an interstimulus interval ranging between 50 and 80 msec the response of the tectal neuron to the latter stimulus was suppressed in most cases. This was true regardless of the order of the stimulus pairing. Concurrent somato‐sensory cortical shocks also suppressed responses to tactile stimuli for 21% of the cells tested.
Supplementary and precentral motor cortex: Contrast in responsiveness to peripheral input in the hindlimb area of the unanesthetized monkey
Authors: Wise S. P. , Tanji J. 
Published: January 2005

AbstractSingle‐unit recording and intracortical microstimulation techniques have been employed in unanesthetized monkeys in order to ascertain the relative responsiveness of the supplementary motor cortex (MII) and the precentral motor cortex (MI) to a controlled peripheral stimulus. The hindlimb representation was explored to facilitate comparison of MI and MII sensitivity in the same animal. Two main findings have emerged: (i) Many fewer neurons in MII respond to the peripheral stimulus and those that do have much weaker responses than neurons in MI. (ii) The hindlimb representation of MII and the tail representation of MI appear to be considerably further rostral than depicted in the classical maps. The latter finding serves to resolve a discrepancy between the classical physiological and cytoarchitectonic maps for this region of cortex.
The emergence, localization, and maturation of neurotransmitter systems during development of the retina in Xenopus laevis. III. Dopamine
Authors: Sarthy P. Vijay , Rayborn Mary E. , Hollyfield Joe G. , Lam Dominic M. K. 
Published: January 2005

AbstractThe uptake, synthesis, and release of dopamine was studied in retinas of Xenopus laevi. In the tadpole and adult retina, 3H‐dopamine is accumulated by cells located in the inner nuclear layer. Retinas preloaded with 3H‐dopamine release this compound in response to high K+ concentrations in the medium. This release is probably Ca++‐dependent as it is inhibited by Co++ in the medium. Adult retinas are also capable of synthesizing 3H‐dopamine from 3H‐tyrosine. The appearance and maturation of these dopaminergic properties were followed during retinal development. Our data indicate that synthesis of dopamine can first be detected as early as stage 35/36 whereas uptake of dopamine first occurs at stage 43. K+‐stimulated release of preloaded 3H‐dopamine from putative dopaminergic neurons is, however, not evident until stage 46. These results show that similar to the development of GABA‐ergic and glycinergic properties, the uptake, synthesis, and release mechanisms for dopamine emerge at different stages during retinal differentiation in Xenopus Laevis.
Morphology of the giant interneurons and cercal nerve projections of the American cockroach
Authors: Daley Darryl L. , Vardi Noga , Appignani Barbara , Camhi Jeffrey M. 
Published: January 2005

AbstractWe have investigated the morphology of the giant interneurons (GIs) and the main sensory projections to these interneurons in the American cockroach. These neurons are thought to mediate the animal's escape behavior. We describe here the dendritic branching pattern of each of the 14 GIs (7 bilateral pairs) in the terminal ganglion, the pattern of projection of the cercal sensory nerve, and the overlap of the cercal projections with the dendrites of the GIs. Visualization of the GIs and cercal nerve projection was accomplished by single cell injection and axonal backfilling with cobalt. Comparisons of the same identified GI in different animals show the position of the soma and the locations and orientations of the major processes are characteristic for each GI. The axons of the cercal nerve project to a well‐defined ipsilateral region of the terminal ganglion. After entering the terminal ganglion, the cercal afferents split into lateral and medial tracts. The projections of the lateral cercal tract overlap extensively with the dendritic fields of the GIs. In contrast, the medial tract does not overlap the dendritic fields of the GIs in the posterior portion of the ganglion and shows only a small degree of overlap in the anterior portion. Correlations between physiological properties of the GIs and cercal afferents are discussed in relation to our anatomical findings.
Localization of neurons in the rat spinal cord which project to the superior cervical ganglion
Authors: Rando T. A. , Bowers C. W. , Zigmond R. E. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) was used to determine the location in the spinal cord of neurons projecting to the superior cervical ganglion of the rat. HRP was applied to the proximal cut end of the cervical sympathetic trunk, close to its entry into the superior cervical ganglion. After survival times of 3, 6, or 9 days, the animals were sacrificed and their spinal cords were processed to visualize HRP using diaminobenzidine, benzidine dihydrochloride, or tetramethylbenzidine. Labeled neurons were found only ipsilateral to the site of HRP application and were restricted to spinal segments C8‐T5. Ninety percent of these neurons were located in segments T1‐T3. Similar numbers of labeled neurons were found at survival times of 3 and 6 days and the mean number ± S.E.M. for 11 experiments at these two survival times was 1575 ± 89. Nine days after application of HRP the mean number of labeled cells and the density of label per cell were reduced. Labeled neurons were found in four regions of the spinal cord: the intermediolateral nucleus (75%), the lateral funiculus (23%), the central autonomic area (1%), and the intercalated region (1%). The cells of the intermediolateral nucleus did not form a continuous column along the rostrocaudal axis of the spinal cord, but instead were often found in clusters, several clusters being present per spinal segment.
Studies on the somatotopy of the trigeminal system in the mallard, Anas platyrhynchos L. IV. Tactile representation in the nucleus basalis
Authors: Berkhoudt Herman , Dubbeldam Jacob L. , Zeilstra Schelte 
Published: January 2005

AbstractThis electrophysiological study complements neuroanatomical work from our department on the somatotopy of the trigeminal system of the mallard. Peripheral areas of mechanoreceptors in bills and tongue were mapped in the telencephalic nucleus basalis, a second‐order relay nucleus in the ascending trigeminal pathway. The multi‐unit responses recorded under Equithesin anaesthesia did not show spontaneous activity and all animals adapted rapidly after mechanical stimulation. They showed well‐circumscribed receptive fields whose peripheral position did not change when the electrode was lowered in the vertical stereotaxic plane, but changed immediately when its position was changed in the horizontal XZ‐plane. The somatotopic picture presented here corresponds in many details to that obtained with combined neuroanatomical techniques (Dubbeldam et al., '81). In the discussion the structural point‐to‐point relationship between the peripheral mechanoreceptive areas and the nucleus basalis is tentatively changed to a division into areas related to the functional units involved in the subsequent sensory events during feeding. The somatotopy provides a basis for future chronic experiments to investigate this postulated role of the various areas in the nucleus basalis.
The structure of the mediodorsal cerebral cortex in the lizard Agama agama: A Golgi study
Authors: Wouterlood F. G. 
Published: January 2005

AbstractA Golgi analysis was made of the cell types present in the mediodorsal cerebral cortex of the lizard Agama agama. Mediodorsal cortex can be divided into two areas, small‐celled mediodorsal cortex (sMDC) and large‐celled mediodorsal cortex (lMDC). Both sMDC and lMDC are four‐layered cortices: superficial plexiform layer, cellular layer, deep plexiform layer and fiber layer, lMDC partially overlaps dorsal cortex (medial superposition). Using characteristics of the dendrites and criteria of location, dendritic field shape and soma size, two classes of neurons can be distinguished in sMDC. The first class consists of two types of solitary cells present in the superficial and deep plexiform layers and in the fiber layer. The second class consists of six types of pyramidal‐like candelabra cells, composing the cellular layer.In lMDC solitary cells are also present in the superficial and deep plexiform layers and in the fiber layer. Large pyramidal cells of one type lie in the cellular layer. In addition, neurons of the dorsal cortex and of the ventral cell plate of Unger lie in the medial superposition area of lMDC. Throughout the entire mediodorsal cortex, protoplasmic and fibrous astrocytes and ependymal tanycytes are found.
Ultrastructure and acetylcholinesterase content of neurones forming connections between the striatum and substantia nigra of rat
Authors: Henderson Zaineb 
Published: January 2005

AbstractNeurones in the striatum and substantia nigra (zona compacta) of the rat were divided into several classes according to differences in morphological appearance and ultrastructural localization of acetylcholinesterase (AChE). To determine which of the neurone types form connections between the substantia nigra and striatum, the ultrastructural localization of AChE was combined with retrograde axonal transport of horseradish peroxidase (HRP). The products of the histochemical reactions for HRP and AChE are localized in separate intracellular compartments and so identification of the efferent cell types was possible.In the striatum there are two morphological classes of AChE‐containing neurone and two or three varieties of cell which do not stain for the enzyme. Only one neurone type projects to the substantia nigra and this is a cell with no AChE which makes up 96% of the total neurone population. In the substantia nigra there are two types of neurone with AChE: a cell with rather variable amounts of AChE which projects to the striatum, and another rarer type, possibly an interneurone.
Ultrastructural changes in olfactory receptor neurons following olfactory nerve section
Authors: Simmons Peter A. , Rafols Jose A. , Getchell Thomas V. 
Published: January 2005

AbstractUnilateral olfactory nerve section was performed in the salamander, Ambystoma tigrinum. An ultrastructural study was performed to investigate the changes occuring during degeneration and replacement of the mature olfactory receptor neurons. Experimental and contralateral control tissues were examined following postoperative survival periods ranging from 12 hours to 90 days. Normal bipolar receptor neurons have a fusiform cell body containing a thin rim of cytoplasm and an ovoid nucleus with a characteristic “checkerboard” chromatin pattern. A single apical dendrite projects to the surface of the epithelium, where numerous cilia extend from its apex into the overlying mucus. A single, unmyelinated, unbranching axon originates at the basal pole of the cell. After nerve section, retrograde degeneration of the mature neurons occurs. Early degenerative changes include pronounced condensation of the nuclear chromatin, increased number of nuclear membrane infoldings, and dilation of the space between the membranes of the nuclear envelope. At a later stage, the cytoplasm of the cell increases in volume and its organelle systems break down, resulting in accumulation of various forms of cell inclusions. Subsequently, proliferation of cells in the basal region of the epithelium occurs. Between 3 week and 2 months following nerve section, these cells differentiate into mature neurons. By 3 months, neurons within the epithelium have resumed their normal ultrastructure. Correlation of the time course of the ultrastructural changes with previously reported neurophysiological studies indicates that neuronal activity of the epithelium is dependent upon the presence of fully differentiated olfactory neurons.