bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectral sensitivities of seven morphological types of photoreceptors in the retina of the turtle, Geoclemys reevesii
Authors: Ohtsuka Teruya 
Published: January 2005

AbstractSpectral sensitivities of photoreceptors in the turtle (Geoclemys) retina were studied by intracellular recording, and each cell was filled with Lucifer yellow (LY). Photoreceptors were classified into seven morphological types: rod, four types of single cones, and two members of a double cone. Single cones contained one of four different oil droplets: red, pale‐green, orange, and clear. Double cones consisted of two apposed cones; principal members contained yellow oil droplets, while accessory members contained no oil droplet. Spectral sensitivities recorded from these seven types of photoreceptors were classified into one type of rod and three chromatic types of cones. Rods (n = 19) showed peak sensitivity at 520 nm. Single cones containing either a red (n = 51) or a pale‐green (n = 9) oil droplet were red‐sensitive (λmax at 620 nm). Single cones containing an orange oil droplet (n = 14) were green‐sensitive (λmax at 540 nm). Single cones containing a clear oil droplet (n = 3) were blue‐sensitive (λmax at 460 nm). Both members of the double cone, principal (n = 22) and accessory (n = 15), were red‐sensitive (λmax at 620 nm) No diffusion of LY was detected between the apposed members of double cones. Red‐sensitive cones, therefore, consisted of four different morphological types of cones, and they occupy about 70% of the photoreceptor mosaic in the turtle retina.
Projections to the basilar pontine nuclei from face sensory and motor regions of the cerebral cortex in the rat
Authors: Mihailoff G. A. , Lee H. , Watt C. B. , Yates R. 
Published: January 2005

AbstractOrthograde axonal transport tracing methods were used to describe the projections to the basilar pontine nuclei (BPN) which arise within the face representation of motor or somatosensory cerebral cortex. Injections centered in motor face (MF) cortex resulted in the labeling of several corticopontine terminal fields which exhibit a rostrocaudal columnar arrangement within the ipsilateral BPN. The location of such terminal zones is consistent with the somatotopic pattern of termination previously described for limb sensorimotor cortices. In contrast, the projections from somatosensory face (SF) cortical regions largely terminate in BPN areas separate from those receiving either limb sensorimotor or MF inputs. Both MF and SF cortices also give rise to projections to the contralateral BPN; those from SF cortex are less extensive than those of MF origin.In addition to their relationship with limb sensorimotor corticopontine terminations, the MF projections to the BPN also seem to partially overlap the projection zones of the cerebellopontine system, particularly the regions projected upon by the lateral cerebellar nucleus. The SF projections, on the other hand, appear to terminate in BPN areas that also receive input from either the dorsal column nuclei or the spinal trigeminal complex. There is only minimal potential overlap between MF and SF projections in the BPN.With regard to the pontocerebellar system, the projections from MF cortex terminate among BPN neurons which project to the cerebellar hemispheres, particularly lobus simplex, crus I and crus II. The SF projections also overlap BPN neurons which project to the lateral hemispheres in addition to the paraflocculus and vermal lobules VII and IXa,b. Taken together these observations suggest that subsets of BPN neurons might exist such that some receive convergent inputs from systems whose function can generally be regarded as motor (sensorimotor cortex, cerebellopontine) while another population of BPN neurons might integrate signals from systems which transmit somatosensory information (dorsal column nuclei, spinal trigeminal).
Ontogeny of tonotopic organization of brain stem auditory nuclei in the chicken: Implications for development of the place principle
Authors: Lippe William , Rubel Edwin W 
Published: January 2005

AbstractThe morphological development of the cochlea begins in the base or midbasal region and spreads toward the apex. In adults, the base responds maximally to high‐frequency sounds and lower frequencies are represented progressively toward the apex. This predicts that responses to sound should occur initially to high frequencies and gradually change to include lower frequencies. Paradoxically, animals respond first to relatively low frequencies and last to high frequencies.We have previously proposed that this discrepancy results from an ontogenetic change in spatial coding of frequency along the cochlea (Rubel et al., '76). According to this model, only the basal end of the cochlea transduces sound early in development but it responds to low frequencies. During maturation the representation of low and midrange frequencies shifts apically and the base becomes responsive to high frequencies, This hypothesis predicts that the tonotopic organization within the central nervous system should change during development; neurons at any given location within an auditory nucleus should become maximally responsive to successively higher frequency sounds during development.In the present study this prediction was tested by using microelectrode recording procedures to map the tonotopic organization of nucleus magnocellullaris (NM) and nucleus laminaris (NL), first‐ and second‐order auditory nuclei, in chickens at three ages: embryonic day 17, 1 day posthatch, and 2–4 weeks posthatch. The characteristic frequencies of neurons having the same anatomical location were quantitatively compared across ages.The tonotopic order in NM and NL was similar at all ages; responses to high‐frequency sounds were recorded anteromedially and lower frequencies were located progressively more caudolaterally. However, there was a striking quantitative change in tonotopic organization. Neurons at a given location in both nuclei became maximally responsive to progressively higher frequencies during development. The characteristic frequencies of neurons in embryos and newly hatched chicks averaged, respectively, 1.00 ((± 0.06, S.E.M.) and 0.34 (± 0.04) octaves lower than their predicted adult values. All regions in both nuclei showed a statistically significant increase in characteristic frequency during development except the most posterolateral (low‐frequency) sector. Too few neurons were recorded from this region to be able to reliably estimate characteristic frequency.These results support the hypothesis that the spatial coding of frequency along the cochlea shifts during development. This has three implications: (1) it helps explain the discrepancy between structural and functional develop‐ ment. (2) it suggests that all neurons will be maximally stimulated by low frequencies at some time during development. (3) it indicates that the values assigned to the place code are not fixed and immutable.
Cytology and intrinsic organization of the perihypoglossal nuclei in the cat
Authors: McCrea R. A. , Baker R. 
Published: January 2005

AbstractThe morphology of the neurons in the perihypoglossal nuclei (nucleus prepositus, nucleus intercalatus, and nucleus of Roller) of the cat was studied in normal Nissl material, and by intracellular injection of horseradish peroxidase.The neurons in the nucleus prepositus were morphologically heterogeneous. Many of the cells in the ventromedial part of the caudal prepositus had relatively large somata, and complex dendritic trees which arose from numerous proximal dendrites and ramified extensively in the ventromedial aspect of the prepositus. These neurons had thick axons which typically did not give rise to local collaterals. The cells in the dorsolateral part of the caudal prepositus tended to have small somata, and dendritic trees which arborized in that region of the nucleus. The axons of these small cells frequently gave rise to local collaterals which terminated in the prepositus. Most of the cells in the prepositus had medium‐sized somata and relatively few dendrites which branched in an isodendritic manner and extended for long distances, frequently leaving the nucleus. These “principal” prepositus neurons had axons which arborized unilaterally, and often gave rise to collaterals which terminated in either the ipsilateral or contralateral prepositus. The neurons in the nucleus of Roller and nucleus intercalatus which were intracellularly injected with horseradish peroxidase resembled the multidendritic and small prepositus cells, respectively.The intrinsic connectivity of the perihypoglossal nuclei was also studied by injecting horseradish peroxidase or 3H‐leucine into the prepositus nucleus. The results of these experiments suggest that the perihypoglossal nuclei are highly interconnected bilaterally, although the large cells in the ventromedial prepositus and the nucleus of Roller contribute little to these intrinsic connections, and are not major recipients of intrinsic inputs. On the other hand, the magnitude of the reciprocal connections between the prepositus and the nucleus intercalatus suggests that they are functionally related.
Cutaneous projections from the rat hindlimb foot to the substantia gelatinosa of the spinal cord studied by transganglionic transport of WGA‐HRP conjugate
Authors: Molander C. , Grant G. 
Published: January 2005

AbstractThe somatotopic organization of cutaneous afferent fibers from the hind‐limb foot in the substantia gelatinosa of the spinal cord was investigated in adult Sprague Dawley rats following intracutaneous injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP). The different parts of the foot were found to project in a precise manner to the medial two‐thirds of the substantia gelatinosa of the spinal cord segments L3–L5. The projections from the digits were arranged in a consecutive row rostrocaudally, with the most medial digit in caudal L3 and the most lateral digit in caudal L4 or rostral L5. The plantar skin was found to project both rostral and caudal to the projection of the digits. The dorsal foot skin projects lateral to the digits, neighboured by the medial edge of the foot rostrally and the lateral edge caudally. Within the projection of a particular digit, the plantar skin was found medially and the dorsal skin laterally. A certain degree of overlap for the projections from the different foot skin areas was found.
Septotemporal distribution of entorhinal projections to the hippocampus in the cat: Electrophysiological evidence
Authors: Van Groen Th. , Da Silva F. H. Lopes 
Published: January 2005

AbstractThe projection of the entorhinal cortex (EA) to the hippocampus in the cat has been studied by electrophysiological methods. Field potentials elicited by EA stimulation sites were measured in the hippocampus (fascia dentata). Different topographic distributions of the amplitude and of the onset latency of average evoked potentials (AEPs) were obtained depending on the place of the stimulation along a lateromedial axis in the Ea. The lateral EA elicited the largest AEPs in the septal part of the hippocampus and the medial EA evoked maximal responses in the temporal part of the hippocampus, while the intermediate part of the EA evoked the largest AEPs in the splenial (intermediate) part of the hippocampus. Unit activity elicited by hippocampal stimulation was measured in the EA. Analysis of the antidromic unit activity showed that the pathways analysed were monosynaptic. Different conduction velocities to the septal part of the hippocampus were found; the pathway from the lateral EA was the fastest and the pathway from the medial EA the slowest. Assuming that the sites of maximal AEP amplitude correspond to the location of the major synaptic inputs, it can be conduced that the active synaptic inputs arising along a lateromedial axis in the EA are distributed within the hippocampus according to a septotemporal axis, although with some overlap between the different projections. Therefore it may be concluded that the hippocampus is not homogeneous with respect to the inputs from the EA. The present observations are discussed regarding anatomical data and putative functional differences between septal and temporal hippocampus.
Central somatostatin systems revealed with monoclonal antibodies
Authors: Vincent S. R. , McIntosh C. H. S. , Buchan A. M. J. , Brown J. C. 
Published: January 2005

AbstractThe distribution of central neurons displaying somatostatin immunoreactivity was studied using three monoclonal antibodies to cyclic somatostatin. The sensitive ABC immunoperoxidase technique was employed. A large number of positive cell groups including many previously undescribed populations were detected throughout the brain and spinal cord. Telencephalic somatostatin neurons included periglomerular cells in the olfactory bulb, mitral cells in the accessory olfactory bulb, and multipolar cells in the anterior olfactory nuclei, neocortex, amygdala, hippocampus, lateral septum, striatum, a ad nucleus accumbens. Within the hypothalamus, positive neurons were found in the periventricular, suprachiasmatic, and arcuate nuclei, and throughout the anterior and lateral hypothalamus. The entopeduncular nucleus and zona incerta contained many positive neurons, and the lateral habenula had a dense terminal field suggesting a pallidohabenula somatostatin pathway.Somatostatin neurons were also found in association with many sensory systems. Positive cells were present in the superior and inferior colliculi, the ventral cochlear nuclei, the ventral nucleus of the lateral lemniscus, nucleus cuneatus, nucleus gracilus, and the substantia gelatinosa.Various cerebellar circuits also displayed somatostatin immunoreactivity. Golgi cells throughout the cerebellar cortex were intensely stained, and some Purkinje cells in the paraflocculus also showed a positive reaction. Positive fibers were present in the granular layer and large varicose fibers were present in the inferior cerebellar peduncle. Many nuclei known to project to the cerebellum, including the nucleus reticularis tegmenti pontis, the medial accessory inferior olive, the nucleus prepositus hypoglossi, and many areas of the reticular formation contained positive neurons.These studies demonstrate that these new monoclonal antibodies are of great value for the study of central somatostatin systems. Previously described somatostatin systems are readily detected with these antibodies, and in addition, many otherwise unrecognized somatostatin cell groups have been discovered.
Cytochrome oxidase staining in the rat smI barrel cortex
Authors: Land Peter W. , Simons Daniel J. 
Published: January 2005

AbstractPatterns of cytochrome oxidase (CO) activity were examined histochemically in the rat SmI cortex. Discrete regions of high enzymatic activity were centered upon the granule cell aggregates (barrels) in layer IV. Those barrels which correspond to the mystacial vibrissae and make up the posteromedial barrel subfield (PMBSF) were especially interesting in that CO staining revealed distinct metabolic subdivisions which do not have an easily demonstrable cytoarchitectonic counterpart. By analogy with the barrels in mouse PMBSF and with the cytoarchitectonically distinct barrels representing the smaller sinus hairs in the rat we propose that regions of high CO activity denote the “hollow” of the rat PMBSF barrels.In accord with previous physiological studies demonstrating a vertical organization in the rodent barrel cortex, we also noted columns of intense CO activity extending from layer VI through sublamina Vb. The centers of these columns coincided with the centers of the barrels in layer IV. In tangential sections through the infragranular laminae the segmentation of CO‐positive zones was less distinct than in layer IV and appeared as bands of heightened activity oriented like the five rows of layer IV barrels. Highly reactive somata, and dendrites were observed in both the granular and infragranular CO barrels indicating that some of the increased activity of these regions reflects oxidative metabolism of cortical neurons per se. These patterns of metabolic activity underscore the vertical and horizontal organization of the SmI vibrissa cortex and suggest that neurons located within the central core of a column have functional properties distinct from those located in zones where individual columns interface.
Plasticity in the rat olfactory cortex
Authors: Westrum L. E. , Bakay R. A. E. 
Published: January 2005

AbstractThe relationship of age to deafferentation plasticity was studied in the rat olfactory cortex (OC). Ablation of a single olfactory bulb (OB) was performed in each of several rats of selected postnatal (PN) ages: PN2.5, 6, 9, 13, and 21 days and in adults of PN100 days. Following survival times sufficient to remove the resultant degeneration, a cortical lesion was placed in the ipsilateral OC. The patterns of degeneration from the OC lesion were studied and mapped in the, adjacent deafferented OC. The results show a spread or sprouting of the usually deep‐lying afferents (interrupted by the OC lesion), onto the deafferented superficial dendrites (normally occupied by the OB afferents) in all of the ages. The spread is most striking at PN2.5 to PN9, gradually reduced by PN13 to PN21, and least in the adult (PN100). There is also an apparent increase of afferents to the deeper dendrites nearer the cell bodies in all cases except in the PN 100 group. Shrinkage of layer I is not seen in PN2.5 subjects, is minimal by PN9, but is most marked in the adult PN100 with total OB lesions. Incomplete OB lesions sparing some lateral olfactory tract (LOT) fibers greatly reduce the shrinkage of layer I and the spread of afferents in all ages. Thus, a capacity for reorganization of afferents occurs at least through PN9, with PN13‐21 a possible “critical period” after which plasticity is limited and transneuronal effects are more permanent. The association, centrifugal, and olfactory‐entorhinal pathways are possible origins for this plasticity. Factors contributing to limitations in this reorganization are discussed.
Structure‐function relationships in rat brainstem subnucleus interpolaris. I. Vibrissa primary afferents
Authors: Jacquin Mark. F. , Woerner Diane , Szczepanik Ann Marie , Riecker Virginia , Mooney Richard D. , Rhoades Robert W. 
Published: January 2005

AbstractIntra‐axonal recording and horseradish peroxidase labelling techniques were used to examine structure‐function relationships for vibrissa‐sensitive primary afferent fibers (N = 40) in rat trigeminal brainstem subnucleus interpolaris (SpVi). All responded at short (mean‐0.42 ms) latencies to trigeminal ganglion shocks and to innocuous stimulation of an individual vibrissa in a slowly adapting type I, slowly adapting type IIa, slowly adapting type IIb, low‐velocity‐sensitive rapidly adapting, or high‐velocity‐sensitive rapidly adapting fashion. As in the medullary dorsal horn (Hayashi, '82; Jacquin et al., '86a), functionally distinct mystacial vibrissae‐related fibers were morphologically indistinguishable. Each gave rise to up to ten collaterals that entered interpolaris perpendicular to the long axis of the nucleus and often overlapped to form a densely packed, highly circumscribed, and largely continuous column of terminal arbors. While some morphological variability was observed both within and between individual axons, variance within a given functional class was no greater than that between classes. Nonmystacial vibrissae afferent arbors also formed similar ovoid, dense circumscribed terminal plexuses. Presumably, these individual arbors collectively form a longitudinal tubelike vibrissae representation in this and other components of the trigeminal brainstem nuclear complex.The relative locations of each fiber's terminal field could be accurately predicted by the particular vibrissa innervated. Contrary to previous data obtained with similar methods (Hayashi, '82), but consistent with the findings of earlier transganglionic tracing (Arvidsson, '82) and histochemical (Belford and Killackey, '79) studies, the arbors of these fibers terminated throughout the mediolateral extent of SpVi. Axons innervating rostral vibrissae terminated medially, and those that supplied caudal vibrissae innervated the lateral SpVi. Dorsal vibrissae were represented in the ventral SpVi, while ventral vibrissae were represented more dorsally. This transverse topography extended largely throughout the rostrocaudal extent of interpolaris. In summary, the vibrissae primary afferent map in SpVi is inverted, faces medially, and is rostrocaudally consistent. In its most caudal aspect, as the displaced substantia gelatinosa swings laterally, the map is less orderly and incomplete. These generalizations also apply to the nonmystacial vibrissae afferents.
Mapping of proctolinlike immunoreactivity in the nervous systems of lobster and crayfish
Authors: Siwicki Kathleen K. , Bishop Cynthia A. 
Published: January 2005

AbstractWhole‐mount immunocytochemical techniques have been used to map candidate proctolin‐containing cells in the central nervous systems of the lobster, Homarus americanus, and the crayfish, Procambarus clarkii. Proctolinlike immunoreactivity was detected in cell bodies and neuropil regions in all central ganglia, and immunoreactive axons were detected in most interganglionic connectives and nerve roots. Cell body staining was confined to fewer than 2% of all cells. Immunoreactive neurons include motoneurons, sensory 'neurons, neurosecretory cells, and interneurons. Colocalization of the proctolinlike antigen with other neurotransmitters was indicated in a number of cases. Many aspects of the distribution of immunoreactivity were similar in lobster and crayfish; however, staining differences were detected in a number of identified neurons and neural groups, including neurons that innervate the pericardial organs and hindgut motoneurons. Further studies of such neurons might provide interesting clues about the physiological functions of proctolin and the evolution of peptide transmission.
Modulatory action and distribution of the neuropeptide proctolin in the crustacean stomatogastric nervous system
Authors: Marder Eve , Hooper Scott L. , Siwicki Kathleen K. 
Published: January 2005

AbstractImmunocytochemical methods were used to map the distribution of proctolinlike immunoreactivity in the stomatogastric nervous systems (stomatogastric ganglion (STG), paired commissural ganglia (CG), oesophageal ganglion (OG), and connecting nerves) of three crustacean species: Panulirus interruptus, Cancer borealis, and Homarus americanus. Although the patterns of proctolinlike staining were similar among the three species, some differences were also observed. Over 70% of the proctolinlike material in STGs, as measured by radioimmunoassay, was indistinguishable from authentic proctolin in reverse‐phase high‐performance liquid chromatography. Bath application of proctolin to STGs from Cancer and Panulirus induced characteristic and robust (though somewhat different) changes in their motor patterns. The threshold concentration was approximately 10−9M proctolin, and the effects were dose‐dependent. These data suggest that the neuropeptide proctolin serves as a neuromodulator of the stomatogastric ganglion.