bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional organization of rat olfactory bulb analysed by the 2‐deoxyglucose method
Authors: Stewart William B. , Kauer John S. , Shepherd Gordon M. 
Published: January 2005

AbstractThe spatial patterns of activity elicited in the rat olfactory bulb under different odor conditions have been analysed using the 2‐deoxyglucose (2DG) technique. Rats were injected with 14C‐2DG, exposed to controlled environments of amyl acetate, camphor, cage air, dimethyl disulfide, and pure air and autoradiographs prepared by the method of Sokoloff. Amyl acetate was associated with regions of glomerular layer densities in the anterolateral and mid‐ to posteromedial parts of the bulbar circumference, as previously reported. The extents of the densities increased with increasing concentration. Camphor odor was associated with regions of increased density in the anterodorsal and mid‐ to posteromedial parts of the bulb. Exposure to cage air produced scattered densities in the posteromedial and posterolateral bulb. Exposure to dimethyl disulfide gave variable results. Pure air was associated with a minimal number of small dense foci.The results with amyl acetate, camphor and cage air suggest that patterns for different odors are distinguishably different but overlapping. The regions of activity are greatest in extent and density with the highest odor concentrations. These define the regions within which more restricted and isolated foci appear at lower concentrations. The results thus provide evidence for the specific role of spatial factors in the neural processing of odor quality and odor concentration.
Localization of vagal cardioinhibitory preganglionic neurons within rat brain stem
Authors: Nosaka Shoichiro , Yamamoto Tetsuro , Yasunaga Koheisho 
Published: January 2005

AbstractIn chloralose‐urethane anesthetized spinal rats, electrical stimulation of systematically chosen points over the entire caudal brain stem area was carried out to explore the site(s) responsible for vagally mediated bradycardia. A dorsomedial locus including the nucleus dorsalis and the adjacent structures, the nucleus tractus solitarius, the nucleus commissuralis and the area postrema, and a ventrolateral locus around the nucleus ambiguus were found to elicit bradycardia with low threshold and high responsiveness. In another series of experiments, horseradish peroxidase (HRP) was iontophoretically administered through a glass capillary microelectrode into the identified cardiac branch of the vagus nerve of rats in order to localize more precisely the cells of origin of vagal cardioinhibitory fibers within the brain stem. Distribution of the HRP‐labeled cells was not confined to one area, but these cells were found within the nucleus dorsalis, the reticular formation surrounding the nucleus ambiguus and an intermediary zone between the two nuclei. Such a pattern of distribution of vagal cardioinhibitory preganglionic cells is discussed in relation to phylogenetic and ontogenetic development of the vagal motor nuclei.
Spinal termination of functionally identified primary afferent neurons with slowly conducting myelinated fibers
Authors: Light A. R. , Perl E. R. 
Published: January 2005

AbstractSingle primary afferent myelinated fibers from cutaneous receptors of cat and monkey were functionally identified by recording from the spinal cord with micropipettes filled with horseradish peroxidase (HRP). Relatively slowly conducting fibers (< 40 m/sec) from high threshold mechanoreceptors (mechanical nociceptors) and two types of low threshold mechanoreceptor (D‐hair and field) were selected for staining. Iontophoresis of the HRP and subsequent histochemical reaction stained the axons recorded from and their collaterals, including terminations, for several millimeters. The termination patterns in the two species proved essentially identical. Ipsilaterally, the mechanical nociceptor fibers terminated principally in the dorsal horn's marginal zone and in the ventral parts of the nucleus proprius (lamina V in the cat). Some of these nociceptors also had terminals in the midline just dorsal to the central canal, contralaterally in the marginal zone, and at the base of the opposite nucleus proprius. In contrast, the D‐hair primary afferent axons terminated in the dorsal part of the nucleus proprius overlapping into the innermost portion of the substantia gelatinosa. The field receptor fibers terminated predominantly in the middle part of the nucleus proprius. These results suggest that there is a highly specialized central projection of primary afferent endings which is related to sensory function and not to fiber diameter. The marginal zone and most dorsal parts of the substantia gelatinosa receive direct projections from cutaneous nociceptors but do not have direct input from cutaneous receptors transmitting activity initiated by innocuous stimulation.
Morphological features of functionally defined neurons in the marginal zone and substantia gelatinosa of the spinal dorsal horn
Authors: Light A. R. , Trevino D. L. , Perl E. R. 
Published: January 2005

AbstractFunctional characteristics of spinal neurons located in the marginal zone (lamina I) and substantia gelatinosa (lamina II) were compared to their structural features by intracellularly staining the source of unitary potentials with horseradish peroxidase (HRP) in unanesthetized, spinal cats. The responses of postsynaptic units to graded electrical volleys in intact dorsal roots and to physiological stimulation revealed that the peripheral excitatory input to neurons of the region is dominated by slowly conducting afferent fibers; often, the input to a given element is largely from a particular class of receptors. One type commonly seen received its principal peripheral excitation from low threshold mechanoreceptors with Aδ or C afferent fibers. Mechanoreceptive elements often exhibited a marked, prolonged habituation and many were not excited by afferent volleys. Other units were predominantly excited by nociceptors with myelinated or unmyelinated fibers, or by thermoreceptors with unmyelinated fibers. A few units (principally the thermoreceptive) showed substantial ongoing activity which was modulated by sensory stimulation, but most had little or none.The HRP staining revealed neuronal morphology in fine detail. No relationship between neuronal configuration and physiological response was discerned. Soma location was not always linked to afferent input, although the cell bodies of nonciceptive and thermoreceptive neurons tended to be in lamina I or outer lamina II (SGo) while those of the inocuous mechanoreceptive neurons tended to be in inner lamina II (SGi). The locus of a neuron's major dendritic arborization was more closely related to the source(s) of peripheral excitation. Cells excited by nociceptors with myelinated fibers had major dendritic projections in the marginal zone. Cells excited by nociceptors or thermoreceptors with unmyelinated fibers had important dendritic branching in the SGo. Innocuous mechanoreceptive neurons had primary dendritic aranching in the SGo. Innocuous mechanoreceptive neurons had primary dendritic arborization in the SGi when the input derived from unmyelinated fibers, or in the SGi and extending into the outer nucleus proprius (lamina III) when the afferent drive came from Aδ fibers.These findings support the concept that laminae I and II constitute a major termination region for thin primary afferent fibers, myelinated fibers from nociceptors ending principally in lamina I and unmyelinated fibers from nociceptors, thermoreceptors, and mechanoreceptors terminating predominantly in lamina II. Substantial integrative and distributive functions can be expected of such an afferent termination zone.
Primary afferent axons in the tract of Lissauer in the cat
Authors: Chung Kyungsoon , Coggeshall Richard E. 
Published: January 2005

AbstractThe present study is concerned with the numbers of primary afferent axons in the tract of Lissauer in the cat. The data show that approximately 27% of the axons in mid‐thoracic and lumbosacral tracts are primary afferent fibers from the segment in question and another 20% of the axons are primary afferent fibers that come from nearby segments. In addition the data show that approximately 80% of the axons in the tract are unmyelinated and that there is a slightly higher proportion of unmyelinated as opposed to myelinated primary afferents. There is also a higher proportion of primary afferents in the medial as opposed to lateral parts of the tract, but there are significant numbers of primary afferents in lateral parts of the tract. Thus it seems clear that the tract contains more primary afferent fibers than was previously believed and if these data are confirmed, the conclusions will have a bearing on considerations of the primary afferent input into the dorsal horn.
An autoradiographic study of the retinotectal projection in the golden hamster
Authors: Chalupa Leo M. , Rhoades Robert W. 
Published: January 2005

AbstractIntracular injections of tritiated leucine and proline were used to examine the retinotectal projection of the golden hamster. In the contralateral superior colliculus intense and complete label was seen in the stratum zonale, stratum griseum superficiale and the upper portion of the stratum opticum, with relatively less dense label in the lower part of the opticlayer. On the ipsilateral side no label was found in the most rostral portion of the tectum. This area comprised about 10% of the rostro‐caudal extent of the colliculus, and most likely, it receives a crossed input from the temporal retina (as demonstrated in the cat by Harting and Guillery, '76). Very sparse label was observed in an anterior segment of the ipsilateral colliculus. In coronal sections it appeared as discrete clumps or patches which were confined to the stratum opticum. Within this layer there was a tendency for the clumps to be located more dorsally with increasing laterality. There was considerable variability between and within animals in the size of the clumps as well as the distance between clumps. Reconstruction of coronal sections showed that the ipsilateral label forms discontinuous ribbons which extend up to 180 microns in the rostro‐caudal dimension. No label was seen on the ipsilateral side in the remaining tectum (caudal 60%).
Afferent projections to the ventral tegmental area of Tsai and interfascicular nucleus: A horseradish peroxidase study in the rat
Authors: Phillipson O. T. 
Published: January 2005

AbstractUsing the retrograde transport of horseradish peroxidase (HRP), a study has been made of projections to the ventral tegmental area of Tsai (VTA) and related dopaminergic cell groups (A 10). In order to minimise the possibility of damage to fibres of passage, a technique was evolved for the microiontophoresis of HRP such that minimal current strengths and durations were applied. In addition to a sham injection, control injections were also made to the medial leminiscus, red nucleus, deep tegmental decussations, mesencephalic reticular formation and brachium conjunctivum. Following HRP injections confined to the areas of the VTA containing the dopamine cell groups, labelled neurons appeared in prefrontal cortex, dorsal bank of rhinal sulcus, nucleus accumbens, bed nucleus of stria terminalis, amygdala, diagonal band of Broca, substantia innominata, magnocellular preoptic area, medial and lateral preoptic areas, anterior, lateral and postero‐dorsal hypothalamus, lateral habenular, nucleus parafascicular nucleus of thalamus, superior colliculus, nucleus raphe dorsalis, nucleus raphe magnus and pontis, dorsal and ventral parabrachial nuclei, locus coeruleus and deep cerebellar nuclei. Regions containing catecholamine goups A 1, A 5, A 6, A 7, A 9, A 13 and the serotonin group B 7 corresponded to the topography of labeled cell groups. Injections of HRP to the interfascicular nucleus resulted in labeling predominantly confined to the medial habenular and median raphe nuclei. The results are discussed in relation to the known connections of these regions. Other regions of the brain labelled by VTA injections are assessed in relation to control injections and the limitations of the HRP technique.A review of the organisation of some of these afferents in relation to the known cortical‐subcortical‐mesencephalic projection systems, suggests that the VTA is in a position to receive information from a massively convergent system derived ultimately from the entire archi‐, paleo‐, and neo‐cerebral cortices. In addition A 10 dopaminergic neurons are known to project to restricted regions of both pre‐frontal and entorhinal cortices, which themselves also receive massively convergent association cortico‐cortical connections. It would appear reasonable to propose that these neurons perform a correspondingly important integrative function.
The decussation of the retinothalamic pathway in the cat, with a note on the major meridians of the cat's eye
Authors: Cooper Michael Lee , Pettigrew John D. 
Published: January 2005

AbstractWe have studied the naso‐temporal division of the retinothalamic pathway of the cat by making large unilateral injections of horseradish peroxidase into the lateral geniculate nucleus. In confirmation of previous work, our retinal whole‐mounts show a distinct vertical decussation line separating the contralaterally projecting nasal retina from the ipsilaterally projecting temporal retina. The ipsilateral decussation line is quite sharp, while the contralateral decussation is somewhat more diffuse, with numbers of large cells extending a few degrees into the temporal retina. However, in contrast to the results of optic tract section, our material (demonstrating the thalamic component only) does not reveal any significant population of contralaterally projecting small cells across most of the temporal retina. The previous observation of approximately 200 μm of naso‐temporal overlap in the area centralis is confirmed here, and evidence is presented that this overlap may in crease at eccentricities above the horizontal meridian.Taken together with previously published data, this demonstration of the vertical decussation line has allowed us to estimate the relative inclinations of the major meridians of the cat's eye.
Spinal projections from the mesencephalic and pontine reticular formation in the north american opossum:A study using axonal transport techniques
Authors: Martin George F. , Humbertson A. O. , Laxson L. C. , Panneton W. M. , Tschismadia I. 
Published: January 2005

AbstractThe results from several experimental approaches lead to the following conclusions. The nucleus cuneiformis projects to at least lumbar levels of the spinal cord. Its axons course through the ipsilateral sulcomarginal and ventral funiculi to distribute within lamina VIII and adjacent portions of lamina VII. Neurons within the nucleus reticularis pontis (RP), particularly within more medial parts of the nucleus, project through comparable routes to the same laminae. In addition, however, neurons within the lateral and dorsolateral RP relay through the lateral and dorsolateral funiculi, ipsilaterally, and the dorsolateral funiculus, contralaterally. Axons could be traced from the dorsolateral tracts to laminae IV through VII, lamina X and, in some instances, to laminae I and II. Injections of the dorsolateral pons also label the intermediolateral cell column and an area presumed to be the sacral parasympathetic nucleus. Many of the neurons which contribute to the contralateral bundle are located adjacent to the ventral nucleus of the lateral lemniscus.The nucleus reticularis gigantocellularis projects mainly via the sulcomarginal, ventral and lateral funiculi to laminae VIII and adjacent portions of laminae VII. The nucleus reticularis gigantocellularis pars ventralis innervates the same laminae; but, in addition, projects heavily to laminae I and II, to lateral portions of laminae IV through VII, to laminae IX and X and to the intermediolateral cell column. Axons destined for laminae I and II, as well as IV through VII and X, traverse the dorsolateral funiculi as described for the cat by Basbaum et al. (1978). Neurons within the nucleus reticularis parvocellularis project to cervical levels, mainly through the ventral funiculi. In general our results show that reticulospinal projections are more complex than suggested by degeneration methods and that laminae I, II, lateral parts of laminae IV‐VII, laminae IX and X, as well as the intermediolateral cell column and sacral parasympathetic nucleus are targets of axons from specific areas.
The origin of descending pathways in the dorsolateral funiculus of the spinal cord of the cat and rat: Further studies on the anatomy of pain modulation
Authors: Basbaum Allan I. , Fields Howard L. 
Published: January 2005

AbstractThere is considerable evidence that the dorsolateral funiculus (DLF) of the spinal cord contains descending pathways critical for both opiate and brainstem stimulation‐produced analgesia. To obtain a comprehensive map of brainstem neurons projecting to the spinal cord via the DLF, large injections of horseradish peroxidase (HRP) were made into the lumbosacral spinal cord of cat and rat. These injections were made caudal to midthoracic lesions which spared only a single DLF or ventral quadrant (VQ); thus only those neurons whose axons descended in the spared funiculus would be labelled.Cells with descending axons in the VQ were concentrated in the medullary nucleus raphe pallidus and obscurus, nucleus retroambiguus and in various subregions of the reticular formation including the nucleus reticularis ventralis, gigantocellularis, magnocellularis, pontis caudalis and pontis oralis. Significant numbers of neurons were also found in medial and lateral vestibular nuclei and in several presumed catecholamine‐containing neurons of the dorsolateral pons. In the rat, but not in the cat, considerable numbers of cells are present in the mesencephalic reticular formation, just lateral to the periaqueductal gray. In both species, some cells were found in the paraventricular nucleus of the hypothalamus.Brainstem cells projecting in the DLF were concentrated in the nucleus raphe magnus and in the adjacent nucleus reticularis magnocellularis, ipsilateral to the spared funiculus. Significant numbers of cells were found in the dorsolateral pons, differing somewhat in their distribution from those projecting in the VQ. DLF‐projecting cells were also present in the ipsilateral Edinger‐Westphal nucleus and periaqueductal grey contralateral red nucleus of the midbrain and in the ipsilateral hypothalamus. Smaller projections from other sites are described.These results are discussed in terms of the differential contribution of several brainstem neuronal groups, including the serotonergic nucleus, raphe magnus, the ventromedial reticular formation of the medulla, and various catecholamine‐containing neurons of the dorsolateral pontine tegmentum to the analgesia produced by opiates and electrical brain stimulation.
Subcortical projections of six visual cortical areas in the owl monkey, Aotus trivirgatus
Authors: Graham J. , Lin C.‐S. , Kaas J. H. 
Published: January 2005

AbstractSubcortical projections of six visual cortical areas (Areas 17 and 18, the Middle Temporal, Dorsomedial and Medial Areas, and the Posterior Parietal Region) in the owl monkey, Aotus trivirgatus, were investigated with autoradiographic methods following injections of tritiated proline. No contralateral projections were demonstrated. While some brainstem structures received input from all six subdivisions of cortex, each cortical area appeared to exhibit its own unique pattern of subcortical projections. All six cortical areas were found to project to the superior and inferior divisions of the pulvinar, reticular nucleus of the thalamus, pretectum and superior colliculus. Other subcortical targets of one or more visual cortical areas were the basal ganglia, claustrum, zona incerta, one or more of the intralaminar nuclei, lateral posterior nucleus, pregeniculate nucleus, dorsal lateral geniculate nucleus, and pontine nuclei. Furthermore, details of corticofugal projections to the dorsal lateral geniculate nucleus, pretectum and superior colliculus varied with the cortical area studied. The projections to the reticular nucleus, pregeniculate nucleus, dorsal lateral geniculate nucleus, the inferior and a portion of the superior division of the pulvinar and the superior colliculus were found to be topographically organized. The targets of the subcortical projections were compared with those of the retina, as revealed by autoradiographic methods following tritiated proline injections of the eye and were found to overlap to varying extents in the superior colliculus, pretectum and dorsal lateral geniculate nucleus and to be segregated in the pregeniculate nucleus. The results substantiate the validity of previous studies in the owl monkey that suggest that the visual cortex is subdivided into several functionally distinct areas and illustrate the complexity of corticofugal influence on visual processing.
Topological analysis of the brain stem of the lungfish Lepidosiren paradoxa
Authors: Thors Frans , Nieuwenhuys Rudolf 
Published: January 2005

AbstractThe ventricular sulcal pattern and the cellular structure of the brain stem of the lungfish Lepidosiren paradoxa have been studied in transversely cut Nissl and Bodian stained sections. Five longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis and the sulcus medianus superior could be distinguished. In the isthmus region a number of obliquely oriented sulci is present. One of these, designated here as sulcus d, continues as a longitudinal groove into the mesencephalon. In Lepidosiren most neuronal perikarya are contained within a diffuse periventricular gray. However, 24 separate cell masses could be delineated. Six of these are primary efferent nuclei, six are primary afferent centers, six nuclei are considered to be components of the reticular formation and the remaining six may be interpreted as “relay” nuclei.The distribution of the cell masses and their relations to the ventricular sulci were studied with the aid of the graphical reconstruction procedure termed topological analysis (cf. Nieuwenhuys, 1974, and fig. 11). This analysis yielded the following results. In the rhombencephalon the gray matter is arranged in four longitudinal columns or areas which have been termed the area ventralis, area intermedioventralis, area intermediodorsalis and area dorsalis. In many places the sulcus intermedius ventralis, the sulcus limitans and the sulcus intermedius dorsalis mark the boundaries between these morphological entities. These longitudinal areas coincide largely, but not entirely, with the so‐called functional columns of Herrick and Johnston. The most obvious incongruity is that the area intermediodorsalis contains, in addition to the nucleus of the solitary tract, two non‐visceral sensory cell masses, namely the magnocellular and parvocellular vestibular nuclei. The four longitudinal zones connot be distinguished in the mesencephalon nor can the sulcus limitans be recognized here. Functionally, however, the medial part of the tegmentum mesencephali may be considered the rostral extreme of the somatic motor column, whereas the remainder of the midbrain contains a number of somatic sensory centers.