bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in the postsynaptic density with long‐term potentiation in the dentate gyrus
Authors: Desmond Nancy L. , Levy William B. 
Published: January 2005

AbstractThe present study documents alterations in the size of the postsynaptic density (PSD) of synapses formed by entorhinal afferents with granule cell dendritic spines with long‐term potentiation (LTP). These changes appear early and persist for at least 60 minutes after LTP‐inducing conditioning stimulation.Each animal received test and conditioning stimulation typical of LTP paradigms. Electron microscopic preparation of the dentate gyri from each animal followed conventional procedures. PSD trace lengths of identified asymmetric synaptic profiles were measured. The total PSD length for four categories of synaptic profiles was determined for each third of the molecular layer. PSD surface area per unit volume of tissue (Sv) was then computed from these data. Statical analysis of the Sv data used multivariate analysis of variance. PSD surface area per synapse was also estimated.Total PSD surface area per unit volume does not change significantly throughout the entire molecular layer with LTP‐inducing conditioning stimulation. However, in the activated portion of the molecular layer, total PSD surface area per unit volume tends to increase with conditioning stimulation.In the middle third of the molecular layer, total PSD surface area per unit volume associated with the concave spine profiles increases significantly while there is a statistically significant decrease in total PSD Sv associated with the nonconcave spine profiles. The PSD surface area per synapse also increases markedly. Since it seems that there is an interconversion of spine synapses from nonconcave to concave with LTP (Desmond and Levy: J. Comp. Neurol. In press, ′86a), these data suggest that potentiated synapses have larger responses because, in part, they have larger neurotransmitter receptive regions.
Synaptic connections of cholecystokinin‐immunoreactive neurons and terminals in the rat fascia dentata: A combined light and electron microscopic study
Authors: Leranth Csaba , Frotscher Michael 
Published: January 2005

AbstractWe report here on the fine structure and synaptic connections of neurons and axon terminals in the rat fascia dentata displaying immunoreactivity to antibodies against cholecystokinin octapeptide (CCK). In the fascia dentata and hilar region, CCK‐immunoreactivity was confined to nonpyramidal neurons that were similar in appearance to basket cells known to use gamma‐aminobutyric acid (GABA) as neurotransmitter. These neurons exhibited dense accumulations of endoplasmic reticulum and infolded nuclei, and established asymmetric and symmetric synaptic contacts with presynaptic terminals. Among those terminals that formed assymetric synaptic contacts, giant mossy fiber boutons arising from granule cell axons were identified.Cholecystokinin‐immunoreactive terminals established symmetric synaptic contacts on the cell bodies and dendrites of granule cells. Similar contacts were formed on nonimmunoreactive hilar neurons. Some of these hilar cells were identified as commissural neurons by retrograde filling with horseradish peroxidase (HRP) following injection of the tracer into the contralateral fascia dentata. Synaptic contacts were rarely observed between immunolabeled pre‐ and postsynaptic elements.The results are discussed with regard to inhibitory processes in the fascia dentata since other studies have shown that CCK is coexistent with GABA in hippocampal nonpyramidal neurons.
Localization of motoneurons innervating the extraocular muscles in salamandra salamandra L. (amphibia, urodela)
Authors: Naujoks‐Manteuffel Christiane , Manteuffel Gerhard , Himstedt Werner 
Published: January 2005

AbstractThe central innervation patterns of the extraocular muscles were investigated in the European fire salamander Salamandra salamandra L. by means of the horseradish peroxidase method. The ipsilateral portion of the nucleus nervi oculomotorii, which is located in the rostral ventral tegmentum mesencephali, supplies the musculi recti inferior and medialis and the musculus obliquus inferior without a clear somatotopic representation of the motoneurons. The musclus rectus superior is innervated mainly by a contralateral portion of this nucleus. A definite nucleus Edinger‐Westphal could not be recognized. The nucleus nervi trochlearis, which rostrally joins the nucleus nervi oculomotorii with a gap of only about 40 m̈m between the nuclei, is situated completely contralateral to the musculus obliquus superior supplied by it. The nucleus nervi abducentis, innervating the musculus rectus lateralis, and the nucleus accessorius nervi abducentis, supplying the musculus retractor bulbi, are found in the ipsilateral medulla oblongata and exhibit a large rostrocaudal extension from the eight cranial nerve to the first root of the vagus nerve. Dendrites of the nucleus nervi oculumotorii and of the nucleus accessorius nervi abducentis extend into neuropil areas receiving primary sensory afferents.
Thalamic projections to retrosplenial cortex in the rat
Authors: Sripanidkulchai Kittisak , Wyss J. Michael 
Published: January 2005

AbstractThe topographic relationships between anterior thalamic neurons and their terminal projection fields in the retrosplenial cortex of the rat were characterized by experiments with the fluorescent dye retrograde labeling technique. The results demonstrate that the anterodorsal (DAD) and anteroventral (AV) nuclei project heavily to retrosplenial granular cortex (Rg) and to a lesser extent to retrospenial agranular cortex (Rag). In contrast, the anteromedial (AM) and lateral dorsal (LD) nuclei project heavily to Rag and more lightly to Rg. Irrespective of terminal field in Rg or Rag, the neuronal cell bodies in AD and AV are organized topographically so that the neurons in the caudal part of each nucleus project to rostral retrosplenial cortex and the neurons in the rostral portion of each nucleus project to the caudal retrosplenial cortex. Further, the ventromedial AD and AV neurons project to rostral retrosplenial cortex, whereas dorsolateral neurons in both nuclei project to caudal retrosplenial cortex. LD neurons display a different topographic organization. The neurons in the medioventral part of LD project primarily to the rostral retrosplenial cortex, and the neurons in lateral LD project to the caudal retrosplenial cortex. This latter projection to the caudal retrosplenial cortex is also contributed to by neurons residing in the mediodorsal part of caudal LD. The neurons in AM that project to the retrosplenial cortex display less segregation than the AV, AD, or LD neurons. In all experiments, a number of neurons in the dorsal ventro‐anterolateral nucleus were labeled by retrosplenial injections. The largest number of cells in this nucleus were labeled after Rag injections, and these were topographically organized such that the neurons projecting to the rostral Rag were located immediately deep to the internal medullary lamina, and the neurons projecting to the caudal Rag were more ventrally located. Very few thalamic neurons have axon collaterals to different areas of the retrosplenial cortex as shown by double labeling experiments. Together, these results demonstrate a highly organized thalamic projection to the retrosplenial cortex.
A quantitative electron microscopic study of the intracellular localization of wheat germ agglutinin in retinal neurons
Authors: Harker Rhodes C. , Stieber Anna , Gonatas Nicholas K. 
Published: January 2005

AbstractPrevious work has established that, following endocytosis, wheat germ agglutinin, like a number of other plasma membrane bound ligands, is transported to the Golgi apparatus‐complex. Previous studies that provided qualitative information about the intracellular distribution of internalized wheat germ agglutinin used techniques that precluded any quantitative conclusions about the relative magnitude of the labeling of endosomes, lysosomes, and the Golgi apparatus‐complex. Using quantitative ultrastructural autoradiography, this study compares the time course and relative magnitude of labeling of various intracellular compartments to the labeling in the Golgi area.Fifteen minutes after intraocular injection, wheat germ agglutinin is confined to the inner surface of the retina and the immediate subsurface neuropil with little labeling of the retinal ganglion cell perikarya. Thirty minutes after injection, the plasma membrane (6.97 ± 1.17), endosomes (10.27 ± 3.98), smooth vesicles and tubules (1.94 ± 1.66), and lysosomes (2.42 ± 1.21) of the retinal ganglion cells are labeled, while the Golgi apparatus‐complex is not labeled (0.29 ± 0.25). (Figures in parentheses are the calculated relative radioactive source density ± the standard deviation.)The relative labeling density of the plasma membrane and endosomes decreases somewhat during the next 90 minutes (plasma membrane, 4.76 ± 0.67; endosomes, 7.23 ± 2.02), while the labeling density of smooth vesicles and tubules and of lysosomes rises (smooth vesicles and tubules, 5.56 ± 0.94; lysosomes, 7.76 ± 1.56). The Golgi apparatus‐complex, which is unlabeled at 30 minutes, is weakly labeled at 2 hours (1.26 ± 0.28).The fact that the lysosomes are already labeled at 30 minutes while the Golgi apparatus‐complex is unlabeled at that time indicates that the transport of wheat germ agglutinin to the Golgi apparatus‐complex is a relatively late phenomenon, and suggests that the bulk of the wheat germ agglutinin destined for lysosomes does not pass through the Golgi apparatus‐complex.
Distribution of vestibular afferents that innervate the sacculus and posterior canal in the gerbil
Authors: Kevetter Golda Anne , Perachio Adrian A. 
Published: January 2005

AbstractThe central distribution of afferents that innervate the macula of the saccule and the crista of the posterior canal was assessed in the gerbil following the direct injection of horseradish peroxidase (HRP) separately into the sensory neuroepithelia of each peripheral receptor organ. Ganglion cells innervating the posterior canal were located in the caudal part of the inferior ganglion, while those cells innervating the saccule were located in the rostral part of the inferior ganglion, scattered in the superior ganglion, and concentrated at the junction (isthmus) between the two. The paths of the central axons of these two groups of ganglion cells through the vestibular root and their division into ascending or descending pathways were similar. However, the distributions of their terminals were different. The posterior canal projected to medial parts of the vestibular nuclear complex. Terminals were found in the medial and superior vestibular nuclei. The posterior canal also projected to the uvula of the cerebellum. The saccule projected to more lateral‐lying brainstem areas. Terminal fields were located in the lateral and descending vestibular nuclei and cell group y. Saccule projections outside the vestibular complex were observed to the lateral cuneate nucleus, the N. gigantocellularis, and the cerebellar cortex. Of the eight areas receiving primary afferent projections from these two organs, only within the medial and descending vestibular nuclei and the cerebellar cortex were overlapping projections observed.
Embryogenesis of arborization pattern and topography of individual axons in N. Laminaris of the chicken brain stem
Authors: Young Steven R. , Rubel Edwin W. 
Published: January 2005

AbstractThis study examined the development of individual axon terminal fields in n. laminaris (NL) of the chicken brainstem. In their mature form axons from the nucleus magnocellularis (NM), second‐order auditory neurons in the chicken brainstem, project bilaterally onto the NL. Axons from the ipsilateral and contralateral NM neurons from spatially segregated, elongated arbors in the dorsal and ventral neuropil of NL, respectively. The long axes of these arbors correspond to physiologically defined isofrequency bands To assess the development of this stereotyped arborization pattern, 6–17 day embryonic chicken brain stems were maintained in vitro while injecting horseradish peroxidase into small groups of axons. Three dimensional reconstructions were made from serial sections and projected onto a cartesian plane for quantitative analyses.At embryonic day 6 (E6), the ventral axons already course beneath the recently migrated NL neurons. The arrival of the dorsal NM axon branches is delayed and their paths are indirect. They first loop dorsally into the the ventricular layer, where they seem to make specific connections with migrating NL neurons and use these as guides to their appropriate positions in the NL.During the period from E9 to E17 the dorsal and ventral terminal fields become similar, each adopting properties of the other's initial pattern. The dorsal terminal fields extend to from bands similar to the early ventral terminal fields, while the ventral terminal fields narrow and appear to shift position in order to achieve the tonotopic specificity characteristic of the early dorsal terminal fields.The results show that a complex, mature pattern of neuronal connections can be formed during development by the combination and reorganization of two simple patterns–each shaped, in turn, by its respective axonal trajectory.
Cytochrome oxidase activity in the rat caudate nucleus: Light and electron microscopic observations
Authors: Difiglia Marian , Graveland Gerda A. , Schiff Leora 
Published: January 2005

AbstractCytochrome oxidase (CO) activity was examined in the neostriatum of normal adult rats at the tight and electron microscopic level. At the light microscopic level a heterogeneous distribution of CO activity was observed and was characterized by patches of high activity ranging in size from 200 to 800 μm surrounded or adjacent to regions of lower activity. The most dorsomedial and ventromedial regions of the caudate nucleus appeared to be consistently high in activity in all animals. At the ultrastructural level CO reaction product was localized to the membranes and intracristal spaces of mitochondria. The most reactive mitochondria (those containing the densest precipitates of reaction product) were found within the dendrites of spiny neurons in all caudate regions. In areas of high CO activity the mitochondria within bundles of myelinated fibers and in many axon terminals were also highly reactive whereas those in neuronal somata, primary dendrites, and glial cells and processes exhibited relatively little activity.Quantitative study showed that mitochondria within dendrites accounted for most of the CO activity in caudate neuropil. The mitochondria within dendrites and axon terminals were more reactive in regions of high CO activity than in regions of low CO activity. No differences in the density of synapses or in the proportions of axospinous and axodendritic synapses were observed between CO‐rich and CO‐poor areas.Heterogeneity in the distribution of CO activity in the caudate nucleus may be related to the “patchy” pattern of localization previously observed for some neostriatal afferents, enzymes, transmitters, peptides, and receptor ligands. Also the present results suggest that differences in metabolic activity between regions of the caudate nucleus may depend more on the relative frequency of neuronal discharge at individual synaptic sites than on the density of synapses present within a given area. The high metabolic demands of spiny dendrites as compared to other neuronal profiles in the neostriatum may reflect their level of synaptic activity, since spines are known to participate in the majority of synapses in the caudate nucleus.
Morphological and physiological survival of goldfish Mauthner axons isolated from their somata by spinal cord crush
Authors: Zottoli Steven J. , Marek Lynn E. , Agostini Mark A. , Strittmatter Sandra L. 
Published: January 2005

AbstractAxon segments isolated from their somata degenerate within days or months depending on species and neuronal type. To better understand the time course of morphological and physiological changes associated with degeneration of axon segments of vertebrate central neurons, we have studied the goldfish Mauthner axon (M‐axon) when it has been separated from its soma by spinal cord crush.M‐axon segments survive morphologically for at least 77 days at 14°C. Cross‐sectional areas of isolated M‐axon segments (measured 25–30 mm caudal to the wound site at postoperative days 64 and 77) were greater than those of control axons at the same level. Sheath areas did not change. Electron microscopic observations at the same spinal cord location indicated no clear changes in the configuration or number of neurofilaments or any other organelle. M‐axon segments studied morphologically after 87 postoperative days had all degenerated.Mauthner axon segments were capable of conducting action potentials and eliciting ipsilateral EMG responses. Repetitive firing of the M‐axon segments elicited EMG responses that fatigued more easily and remained fatigued over a longer interval than did those of control axons.The long duration of M‐axon segment survival is unusual in a vertebrate and may be due to the low temperature at which the experiments were conducted (14°C) and/or temperature‐independent factors. The increased susceptibility to synaptic depression, which has not reported previously, may represent an early sign of the degenerative process.
Morphological and physiological studies of rod‐driven horizontal cells with special reference to the question of whether they have axons and axon terminals
Authors: Tsukamoto Yoshihiko , Yamada Masahiro , Kaneko Akimichi 
Published: January 2005

AbstractRod‐driven (intermediate) horizontal cells were examined in the carp retina to determine whether they bear axons and axon terminals. These cells were injected with HRP after physiological identification of the response type; which consisted of a higher sensitivity to light and a slower response time course than cone‐driven (external) horizontal cells, and spectral sensitivity peaking at 520 nm. The labeled cells were further identified morphologically by tracing their dendrites to rod photoreceptors by light and electron microscopy. About two‐thirds of the labeled cells (18/30) had a slender, axonlike process (<1 μm in diameter, 70–300 μm in length) running horizontally from the soma. No axonlike process was found in the remaining cells. Unlike the axons of external horizontal cells, this axonlike process was short and did not form a long fusiform expansion. No membrane specialization was found along the axonlike process.Since it has been reported that the syncytium made of axon terminals of external horizontal cells serves as a signal bypass of the syncytium made of the somata, it was asked, in separate experiments, whether the intermediate horizontal cells also had such a double syncytial layer. Response amplitudes to a slit of light were measured by placing the slit at various distances from the recording electrode. The response amplitude decayed with distance with a single exponential function, indicating that the syncytium of intermediate horizontal cells consists of a monolayer. These physiological data are consistent with the morphological observations.
The structural and functional characteristics of tectospinal neurons in the golden hamster
Authors: Rhoades Robert W. , Mooney Richard D. , Klein Bradley G. , Jacquin Mark F. , Szczepanik Ann Marie , Chiaia Nicolas L. 
Published: January 2005

AbstractIntracellular recording and horseradish peroxidase (HRP) injection techniques were used to delineate the structural and functional characteristics of the superior collicular cells in the hamster, which could be antidromically activated from the first cervical segment of the spinal cord. Thirty‐one such neurons were characterized, filled with HRP, and recovered. Complete physiological data were obtained from another 21 tectospinal cells for which anatomical data were sufficient only to define the laminar location of the cell body from which recordings were made. Of the total sample of 52 cells, 7.7% had their somata in the stratum griseum intermediale (SGI), 50% were in the stratum album intermedium (SAI), 36.5% were in the stratum griseum profundum (SGP), and 5.8% were in the stratum album profundum (SAP). The tectospinal cells were fairly uniform morphologically. They had large (27.7 ± 5.5 μm diameter) cell bodies, which gave rise to an average of 6.7 ± 1.2 primary dendrites. These were generally smooth and extended up to 500 μm away from the cell body. In many cases, they ascended out of the deep laminae into the stratum opticum (SO) and/or stratum griseum superficiale (SGS). The axons of TS cells averaged 3.4 ± 0.8 μm in diameter, and they generally coursed radially to the SAP where they curved around the periaqueductal gray and entered the predorsal bundle. These axons often gave rise to collaterals that arborized in the deep laminae of the ipsilateral superior colliculus and subjacent reticular formation.The tectospinal cells were also fairly uniform physiologically. Their average conduction latency was 2.0 ± 2.3 ms, and this variable had a strong negative correlation (−.81) with axon diameter for the recovered cells. Most (63.5%) of the TS cells were exclusively somatosensory and gave rapidly adapting responses to deflection of vibrissae and/or guard hairs; 7.7% were bimodal (visual‐somatosensory); 11.5% had complex (Rhoades et al., '83) somatosensory receptive fields; 1.9% were discharged only by a noxious pinch, and 15.4% were unresponsive. A common feature of all bimodal tectospinal neurons was dendrites that extended at least as far dorsally as the SO. Whereas there were no other clear‐cut correlations between the structural and functional characteristics of these tectal neurons, we did note that all of the cells with complex somatosensory receptive fields received inhibitory input from axons that either originated from, or passed through, the contralateral superior colliculus.
Do early lesions affect cell death in the central nervous system? A study on the effects of early cerebellar hemispherectomy in rats
Authors: Gramsbergen A. , Ijkema‐Paassen J. 
Published: January 2005

AbstractCell death patterns in the lateral and interposed nuclei were compared in control rats and rats in whom a unilateral cerebellar hemispherectomy was performed at day 2 of life. Both groups were studied between days 2 and 20 of life. Pyknotic cells and live neuronal and glial cells were counted from Nissl stained sections. After correction of these values, pyknotic to live cell ratios were calculated. In the lateral nucleus of normal rats, around 14–28 pyknotic cells per 1,000 live cells occurred from day 2 to day 12. Thereafter this value decreased, and from day 16 less than 3 pyknotic/1,000 live cells were observed. In the interposed nuclei, 18–28 pyknotic cells/1,000 live cells occurred at day 2, and from this age onward values gradually decreased. At day 20 values ranged around 1.6/1,000. After unilateral cerebellar hemispherectomy, values in both nuclei began to decrease as early as from day 8. Results from the present study strongly suggest that these cells are prevented from dying because they find an aberrant synaptic target in the ipsilateral red nucleus. Our results demonstrate that early lesions interfere with the regulation of fundamental processes of neuro‐ontogeny.