bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution of neurons born during embryonic and adult life to the brain of adult canaries: Regional specificity and delayed birth of neurons in the song‐control nuclei
Authors: Alvarez‐Buylla Arturo , Ling Chang‐Ying , Yu Wen Shan
Published: January 2005

Neurogenesis occurs in adult song birds, which suggests that neurons born after hatching may contribute to histogenesis and plasticity of the avian brain. However, little is known about the overall contribution to the mature brain of neurons born in juveniles and adults, and how this process affects different regions of the avian brain. In fact, studies of the histogenesis of the avian forebrain have made the classical assumption that neuronal birth ends before hatching. Here we determined the contribution of neurons born before and after hatching to different regions throughout the adult canary brain. Male canaries were injected with [3H]‐thymidine at different times during embryonic, juvenile, and adult life. The position of labeled neurons was mapped in parasagittal brain sections. Because all birds were killed as adults, results indicate the time of birth of neurons that survived to adulthood in different structures of the avian brain. Injection at embryonic day (E) 5 or E9 resulted in labeled neurons in all regions of the neuroaxis. The vast majority of neurons outside of the telencephalon were born before E9. One exception was a discrete region in the dorsal thalamus, a part of the song‐control circuit, where neurons continued to be born after E9. Most regions of the telencephalon had a high proportion of its neurons labeled by the embryonic injections. In particular, archistriatum, anterior neostriatum, and the hippocampus had most of their neurons labeled before hatching. This indicates that many of the telencephalic neurons born in the embryo are long lived and are not replaced by other neurons that continue to be added to the telencephalon after hatching. Neurons labeled by [3H]‐thymidine injections after hatching were restricted to the telencephalon and contributed importantly to many regions. In particular, the avian striatum (lobus parolfactorius, LPO) received a large number of its neurons during the first 20 days of life, but continued to incorporate new neurons throughout juvenile and adult life. Neurons continued to be added to the telencephalon of adults (even in 4‐year‐old birds). The distribution of labeled neurons after [3H]‐thymidine injections in adults was similar to that observed in latter stages of juvenile development. The contribution of neurons born at different ages from embryonic development to adulthood varied among different anatomical subdivisions of the canary brain. This could, in part, explain differences in the cytoarchitecture and plasticity between brain regions. Neurogenesis after hatching may allow the modification of selected brain circuits as the bird matures and ages. © 1994 Wiley‐Liss, Inc.
Immunohistochemical localization of substance P receptor in the central nervous system of the adult rat
Authors: Nakaya Yoshifumi , Kaneko Takeshi , Shigemoto Ryuichi , Nakanishi Shigetada , Mizuno Noboru
Published: January 2005

In an attempt to reveal the function sites of substance P (SP) in the central nervous system (CNS), the distribution of SP receptor (SPR) was immunocytochemically investigated in adult rat and compared with that of SP‐positive fibers. SPR‐like immunoreactivity (LI) was mostly localized to neuronal cell bodies and dendrites. Neurons with intense SPR‐LI were distributed densely in the cortical amygdaloid nucleus, hilus of the dentate gyrus, locus ceruleus, rostral half of the ambiguus nucleus, and intermediolateral nucleus of the thoracic cord; moderately in the caudatoputamen, nucleus accumbens, olfactory tubercle, median, pontine, and magnus raphe nuclei, laminae I and III of the caudal subnucleus of the spinal trigeminal nucleus, and lamina I of the spinal cord; and sparsely in the cerebral cortex, basal nucleus of Meynert, claustrum, gigantocellular reticular nucleus, and lobules IX and X of the cerebellar vermis. Neurons with weak to moderate SPR‐LI were distributed more widely throughout the CNS. The regional patterns of distribution of SPR‐LI were not necessarily the same as those of SP‐positive fibers. The entopeduncular nucleus, substantia nigra, and lateral part of the interpeduncular nucleus showed intense SP‐LI but displayed almost no SPR‐LI. Conversely, the hilus of the dentate gyrus, anterodorsal thalamic nucleus, central nucleus of the inferior colliculus, and dorsal tegmental nucleus showed intense to moderate SPR‐LI but contained few axons with SP‐LI. These findings confirmed the presence of the “ismatch” problem between SP and SPR localizations. However, the distribution of SPR‐LI was quite consistent with that of the SP‐binding activity, which has been studied via autoradiography. This indicates that the sites of SPR‐LI revealed in the present study represent most, if not all, sites of SP‐binding activity. © 1994 Wiley‐Liss, Inc.
Nature and origin of cerebrovascular nerves with substance P immunoreactivity in bats (Mammalia: Microchiroptera), with special reference to species differences
Authors: Andō Koichi , Ishikawa Atsushi , Okura Nobuhiko
Published: January 2005

Double staining immunohistochemistry was used to investigate the origin and projection of nerves with substance P (SP) immunoreactivity (‐IR) in the walls of the major cerebral arteries in two microchiropteran species. In the greater horseshoe bat, most of the cerebral perivascular nerves with SP‐IR did not exhibit calcitonin gene‐related peptide (CGRP)‐IR, but emitted bright immunofluorescence for vasoactive intestinal polypeptide (VIP). In this species, a large number of cell bodies with both SP‐ and VIP‐IR were observed in many cranial ganglia along various branches of the facial and glossopharyngeal nerves. There were no cell bodies immunoreactive for either SP and VIP in the two sensory (trigeminal and upper cervical dorsal root), two sympathetic (superior cervical and stellate), or two vagal (superior and jugular) ganglia. In addition, several thick fiber bundles with both SP‐ and VIP‐IR were present in the wall of the cerebral carotid artery, and descended progressively reaching as far as the middle part of the basilar artery (BA). These and other findings suggest that SP‐immunoreactive nerves with VIP‐IR but not CGRP‐IR, which contribute to the rich innervation of the vertebrobasilar system in the greater horseshoe bat, originate from neurons with the same combination of peptide‐IR in the major or local facial or glossopharyngeal parasympathetic ganglia, and enter the cranial cavity along the internal carotid artery. In the bent‐winged bat, however, cerebral perivascular SP‐immunoreactive nerves, as well as SP‐immunoreactive neurons within the trigeminal and upper cervical dorsal root ganglia (uCDRG), showed neither CGRP‐IR nor VIP‐IR, and were mostly confined to the caudal BA and the vertebral artery (VA). These observations, in addition to the projection of this nerve type to the BA via the VA as fiber bundles, or through the meninges, indicate that the principal source of the cerebrovascular SP‐immunoreactive innervation in this species is the uCDRG. © 1994 Wiley‐Liss, Inc.
Local and commissural neuropeptide‐containing projections of the nucleus of the solitary tract to the dorsal vagal complex in the pigeon
Authors: Berk Mitchell L. , Smith Stacy E.
Published: January 2005

The neuropeptide content of neurons of the nucleus of the solitary tract (NTS), which have local and commissural projections to the dorsal motor nucleus of the vagus (DMNX) and to NTS, were demonstrated in the pigeon (Columba livia) by using a combined fluorescein‐bead retrograde‐transport‐immunofluorescence technique. The specific peptides studied were bombesin, cholecystokinin, enkephalin, galanin, neuropeptide Y, neurotensin, and substance P. Perikarya immunoreactive for bombesin were located in the Medial tier subnuclei of NTS and the caudal NTS. Most galanin‐ and substance P‐immunoreactive cells were found in subnucleus medialis ventralis. Cells immunoreactive for neuropeptide Y were found in the medial tier of NTS and in the lateral tier, especially in subnucleus lateralis dorsalis intermedius. The majority of enkephalin‐ and neurotensin‐immunoreactive cells were found centrally in subnuclei medialis dorsalis and medialis intermedius. Cells immunoreactive for cholecystokinin were located in subnuclei laterolis dorsalis pars anterior, medialis superficialis, and the caudal NTS.

Based on the presence of retrogradely labeled cells, numerous neurons of the medial tier of NTS, but extremely few lateral tier NTS neurons, had projections to the ipsilateral and contralateral DMNX and NTS. The number of retrogradely labeled NTS cells was always greater ipsilateral than contralaterally. The percentages of peptide‐immunoreactive NTS cells that projected to the ipsilateral and contralateral DMNX were in the ranges of 29–61% and 10–48%, respectively. The percentages of peptide‐immunoreactive NTS cells that projected to the contralateral NTS ranged from 13 to 60%. Peptide‐immunoreactive NTS cells that have local and commissural projections to DMNX and NTS may act as interneurons in vagovagal reflex pathways and in the integration of visceral sensory and forebrain input to NTS and DMNX. © 1994 Wiley‐Liss, Inc.
Neocortex provides direct synaptic input to interstitial neurons of the intermediate zone of kittens and white matter of cats: A light and electron microscopic study
Authors: Shering Andy F. , Lowenstein Pedro R.
Published: January 2005

The existence of direct synaptic input from the neocortex to intermediate zone and white matter interstitial neurons was examined in both neonate and adult cats. This projection was studied by injecting the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) into the neocortex and examining whether cortical efferent axons formed synapses in the intermediate zone or white matter. Anterogradely labeled boutons establishing synapses in the intermediate zone and white matter were found at the electron microscopic level after injecting PHA‐L into the primary visual, somatosensory, and suprasylvian cortex. Although labeled synapses were found in the intermediate zone of kittens injected at postnatal days 2 and 6, their morphological features appeared immature compared to those found in kittens aged 3 weeks or in adults. Postsynaptic targets of efferent cortical axons were studied in serial sections and shown to be dendritic shafts and spines.

This paper shows that cortical efferent axons contribute synapses to interstitial neurons located in the intermediate zone of kittens and white matter of adults. The functional role of the corticointermediate zone/white matter projection remains to be determined. © 1994 Wiley‐Liss, Inc.
Organization of projections from the anterior hypothalamic nucleus: A Phaseolus vulgaris‐leucoagglutinin study in the rat
Authors: Risold P. Y. , Canteras N. S. , Swanson L. W.
Published: January 2005

Anterior hypothalamic nucleus (AHN) projections were examined with the Phaseolus vulgaris‐leucoagglutinin (PHA‐L) method in adult male rats. Labeled axons from the AHN follow three major routes. 1) A large ascending pathway ends densely in the telencephalon, particularly in the lateral septal nucleus. Axons along this route provide moderate to dense input to the medial and lateral preoptic areas, and a few are also observed in the septofimbrial nucleus and fimbria; the latter end in the temporal hippocampus. A few axons reach the amygdala through the bed nuclei of the stria terminalis, which receive a moderate input, and then the stria terminalis, and others reach it by way of the ansa peduncularis. 2) The second pathway travels dorsal to the AHN, ending densely in rostral perifornical regions of the lateral hypothalamic area, and the rostral ventrolateral tip of the nucleus reuniens. The parataenial and rostral paraventricular thalamic nuclei also receive a significant input. Some fibers and boutons were also observed in the rhomboid, interanterodorsal, and mediodorsal nuclei, and others course through the stria medullaris to the lateral habenula. 3) the largest pathway descends through dorsal and ventral routes in the medial hypothalamic zone before ending massively in the periaqueductal gray. Dorsal route fibers provide inputs to the zona incerta and posterior hypothalamic nucleus, whereas more ventral axons generate dense terminal fields in the ventromedial nucleus capsule and core, and dorsal premammillary nucleus. The retrochiasmatic area, dorsomedial nucleus, and medial supramammillary nucleus also receive significant inputs, and a few axons end in the subparafascicular nucleus, superior colliculus, and mammillary body. The caudalmost axons were seen in the pontine central gray and reticular formation. These pathways are bilateral, usually with a distinct ipsilateral predominance. The overall pattern of efferents from anterior, central, and posterior parts of the AHN is similar, whereas the relative densities of particular terminal fields may vary considerably. Projections from adjacent parts of the retrochiasmatic and perifornical areas are also described. The results are discussed in terms of neural circuitry that may be involved in mediating interactions between animals. © 1994 Wiley‐Liss, Inc.
Immunocytochemical localization of amyloid precursor protein in rat brain
Authors: Ouimet Charles C. , Baerwald Kristine D. , Gandy Samuel E. , Greengard Paul
Published: January 2005

The localization ofamyloid precursor protein (APP) in rat brain was studied with a cytoplasmic domain‐specific antibody. Light microscopic immunocytochemistry demonstrated that APP is present in most neurons, in some oligodendrocytes, and in a population of cells with diameters less than 10 μm that may be glial. Marked differences in immunoreactivity among neurons were observed, and the strongest immunoreactivity was contained in larger neurons. Neurons with scant cytoplasm, such as granule cells in the olfactory bulb, dentate gyrus, and cerebellum, were weakly immunoreactive. Differences in neuropil immunoreactivity were also observed; this type of staining was strongest in the caudatoputamen, lateral septum, medial habenula, nucleus reticularis of the dorsal thalamus, and the lateral portion of the ventroposterior nucleus. Neuropil immunostaining was weakest in layer IV of cortex and in areas containing granule cells. The fact that APP seems to be present in the vast majority of neurons suggests that this protein plays a role common to all neurons. The fact that there is a great difference in the steady‐state amount of APP among different types of neurons suggests that APP may play a specific role in the function of certain classes of neurons. © 1994 Wiley‐Liss, Inc.
Physiology and morphology of complex spiking neurons in the guinea pig dorsal cochlear nucleus
Authors: Manis Paul B. , Spirou George A. , Wright Debora D. , Paydar Sussan , Ryvgo David K.
Published: January 2005

Intracellular recordings from the dorsal cochlear nucleus have identified cells with both simple and complex action potential waveforms. We investigated the hypothesis that cartwheel cells are a specific cell type that generates complex action potentials, based on their analogous anatomical, developmental, and biochemical similarities to cerebellar Purkinje cells, which are known to discharge complex action potentials. Intracellular recordings were made from a brain slice preparation of the guinea pig dorsal cochlear nucleus. A subpopulation of cells discharged a series of two or three action potentials riding on a slow depolarization as an all‐or‐none event; this discharge pattern is called a complex spike or burst. These cells also exhibited anodal break bursts, anomalous rectification, subthreshold inward rectification, and frequent inhibitory postsynaptic potentials (IPSPs). Seven complex‐spiking cells were stained with intracellular dyes and subsequently identified as cartwheel neurons. In contrast, six identified simplespiking cells recorded in concurrent experiments were pyramidal cells.

The cartwheel cell bodies reside in the lower part of layer 1 and the upper part of layer 2 of the nucleus. The cells are characterized by spiny dendrites penetrating the molecular layer, a lack of basal dendritic processes, and an axonal plexus invading layers 2 and 3, and the inner regions of layer 1. The cartwheel cell axons made putative synaptic contacts at the light microscopic level with pyramidal cells and small cells, including stellate cells, granule cells, and other cartwheel cells in layers 1 and 2. The axonal plexus of individual cartwheel cells suggests that they can inhibit cells receiving inpt;t from either the same or adjacent parallel fibers and that this inhibition is distributed along the isofrequency contours of the nucleus. © 1994 Wiley‐Liss, Inc.
Distribution of Purkinje cell‐specific Zebrin‐II/aldolase C immunoreactivity in the mouse, rat, rabbit, and human retina
Authors: Caffé A. R. , von Schantz M. , Szél A. , Voogd J. , van Veen T.
Published: January 2005

The developmental, genetic, and biochemical similarities that have been observed between the cerebellum and retina form the basis for ongoing investigations into retinal expression of cerebellar‐specific proteins. We have examined the mouse, rat, rabbit, and human retina for expression of a protein that is present in parasagittal Purkinje cell strips and that is recognized by the antibody Zebrin‐II. This protein has recently been identified as a member of the aldolase C isoenzymes. Western blotting and immunocytochemistry have been used.

The monoclonal antibody Zebrin‐II recognized a prominent 36 kDa protein band on immunoblots of both the cerebellum and the retina of the examined species. Immunocytochemistry showed that, in the three nonhuman species, cells were stained in the ganglion cell layer (GCL). In addition, in the mouse and rabbit, cells in the inner nuclear layer (INL) were also labeled. Except for the visual streak, there were more immunopositive cells in the rabbit GCL and INL than in corresponding areas of the mouse retina. In the human, in contrast to the other species, the photoreceptor cell layer was strongly aldolase C immunoreactive. In the h all species except for the rat, the photoreceptor inner segments also displayed a weak labeling.

The results show that this aldolase C isoenzyme is another protein that is selectively expressed by the cerebellum: and retina. Furthermore, the retinal expression is species specific, and this pattern seems to show a good correlation with the oxygenation level of the individual compartments. The indication that this aldolase C isoenzyme has specific developmental functions in the retina provides additional clues for our understanding of cerebellar organization. © 1994 Wiley‐Liss, Inc.
Undernutrition during early life does not affect the number of granule cells in the rat olfactory bulb
Authors: Tolley Lynn K. , Bedi Kuldip S.
Published: January 2005

Undernutrition during early life causes deficits and distortions of brain structure. However, whether or not this includes a diminution of the total numbers of neurones remains uncertain. Recent advances in stereological techniques have made it possible to obtain unbiased cells in well‐defined biological structures. Rats were undernourestimates of total number of cells in well‐defined biological structures. Rats were undernourished from conception to 90 postnatal days of age by standardised procedures. Groups of well‐fed control and undernourished rats were anaesthetised and killed by intracardiac perfusion with fixatives at 30 and 90 days of age. Each olfactory bulb was serially sectioned at a nominal thickness of 100 pm on a vibratome. These sections were analysed by the Cavalieri principle to obtain estimates of the total volume of the olfactory bulb as well as the volume of its granule cell layer. The physical “disector” method was later used on serial 1‐μm‐thick toluidine‐blue‐stained sections to estimate the numerical density of granule cell neurones in the olfactory granule cell layer. These values were used to compute estimates of the total number of olfactory granule cell neurones for each animal. Thirty‐day‐old control and undernourished rats had between 2.6 and 3 million granule cell neurones in the olfactory bulb. By 90 days of age the number of granule cells had increased in both groups of animals to between about 4.2 and 5.2 million cells. Analysis of variance tests showed a significant main effect of age but not nutrition in these estimates. Although the interaction term did reach statistical significance, post hoc analysis did not reveal any differential effect of undernutrition between the two age groups examined. Therefore, undernutrition of rats from conception until 90 postnatal days of age does not seem to affect the total numbers of granule cell neurones in the olfactory bulbs. © 1994 Wiley‐Liss, Inc.
Anatomical connections of the primate pretectal nucleus of the optic tract
Authors: Mustari Michael J. , Fuchs Albert F. , Kaneko Chris R. S. , Robinson Farrel R.
Published: January 2005

The pretectal nucleus of the optic tract (NOT) plays an essential role in optokinetic nystagmus, the reflexive movements of the eyes to motion of the entire visual scene. To determine how the NOT can influence structures that move the eyes, we injected it with lectin‐conjugated horseradish peroxidase and characterized its afferent and efferent connections. The NOT sent its heaviest projection to the caudal half of the ipsilateral dorsal cap of Kooy in the inferior olive. The rostral dorsal cap was free of labeling. The NOT sent lighter, but consistent, projections to other visual and oculomotor‐related areas including, from rostral to caudal, the ipsilateral pregeniculate nucleus, the contralateeral NOT, the lateral and medial terminal nuclei of the accessory optic system bilaterally, the ipsilateral dorsolateral pontine nucleus, the ipsilateral nucleus prepositus hypoglossi, and the ipsilateral medial vestibular nucleus. The NOT received input from the contralateral NOT, the lateral terminal nuclei bilaterally, and the ipsilateral pregeniculate nucleus. Although our injections involved the pretectal olivary nucleus (PON), there was neither orthograde nor retrograde labeling in the contralateral PON. Our results indicate that the NOT can influence brainstem preoculomotor pathways both directly through the medial vestibular nucleus and nucleus prepositus hypoglossi and indirectly through both climbing and mossy fiber pathways to the cerebellar flocculus. In addition, the NOT communicates strongly with other retino‐recipient zones, whose neurons are driven by either horizontal (contralateral NOT) or vertical (medial and lateral terminal nuclei) fullfield image motion. © 1994 Wiley‐Liss, Inc.
Projections from the lateral and interposed cerebellar nuclei to the thalamus of the rat: A light and electron microscopic study using single and double anterograde labelling
Authors: Aumann T. D. , Rawson J. A. , Finkelstein D. I. , Horne M. K.
Published: January 2005

The lateral and interposed cerebellar nuclei may have different functions in the control of movement. Efferent fibres from both nuclei project predominantly to areas of the thalamus, which in turn project to the motor cortex. In this study, single and double anterograde‐tracing techniques have been used to examine and compare the pathways from the lateral and interposed nuclei to the thalamus in the rat by using both light and electron microscopy to look for evidence of organisational or structural features that may underlie the proposed functional differences between these nuclei.

Terminals from the lateral nucleus were found to be located most medially in the thalamus, predominantly in the ventral lateral nucleus and the rostral pole of the posterior nuclear group. Terminals from the posterior interposed nucleus were located slightly rostral and lateral to those from the lateral nucleus, mainly around the border between the ventral lateral nucleus and the ventral posterior medial nucleus. Terminals from the anterior interposed nucleus were located slightly rostral and lateral to those from the posterior interposed nucleus, predominantly in the rostral pole of the ventral posterior lateral nucleus. Terminals from the lateral and interposed nuclei were also found in double anterograde‐tracing experiments to be nonoverlapping in the regions between these main areas of termination. The structure of terminals from the lateral and interposed nuclei, however, as well as their synaptic relationship with thalamic neurones, were found to be similar. The terminals are large and form synapses with proximal dendrites of thalamic neurones. They contained round vesicles and formed multiple synaptic contacts with dendritic shafts, as well as dendritic spines.

The findings indicate that information from the lateral and interposed nuclei is processed in separate regions of the thalamus but that the mode of synaptic transfer to thalamic neurones is likely to be similar for the two projections. © 1994 Wiley‐Liss, Inc.
Distribution of calcium‐binding protein calbindin‐D28k in the auditory system of adult and developing rats
Authors: Friauf Eckhard
Published: January 2005

Calbindin‐D28k (CaBP) is a calcium‐binding protein, which appears to be involved in the buffering of free intracellular calcium and may thereby contribute to calcium homeostasis. This study attempted to determine the distribution pattern of CaBP immunoreactivity in the central auditory system of adult rats and during development, when calcium ions play key roles in several aspects of nerve cell function. It was found that most steps during CaBP development occur postnatally in the central auditory system. With the exception of the lateral superior olive, the ventral and the intermediate nuclei of the lateral lemniscus, and the auditory cortex, which already express CaBP prenatally, CaBP immunoreactivity is not present before postnatal day 2 (P2). Development proceeds until about P24, when the pattern characteristic of adult animals can be seen. There was no detectable sequence in CaBP development from lower to higher stations in the auditory pathway, i.e., the different nuclei appear to express CaBP independently of each other, indicating that intrinsic, rather than peripheral, maturation processes may predominantly influence CaBP expression.

Neurons in four brainstem nuclei (the lateral superior olive, the ventral and intermediate nuclei of the lateral lemniscus, and the central nucleus of the inferior colliculus) express CaBP only transiently. In these nuclei, CaBP immunoreactivity peaks between P6 and P18, which coincides with the period of synapse stabilization. Therefore, CaBP may play a specific role during neuronal development, by buffering the concentration of intracellular free Ca2+, which may be necessary for modification of synaptic efficiency. © 1994 Wiley‐Liss, Inc.
Paraventriculospinal tract as a model for axon injury: Spinal cord
Authors: van den Pol Anthony N. , Collins William F.
Published: January 2005

The response of immunocytochemically identified hypothalamic axons innervating the rat spinal cord was examined at varying times after cord hemisection in a model of axonal injury using the paraventriculospinal projection. The purpose was to determine whether these long descending peptidergic axons would show signs of regrowth after injury. From 1 to 180 days after hemisection, horizontal sections of the spinal cord were stained with peroxidase immunocytochemistry. Antiserum against neurophysin was used to identify axons projecting from the hypothalamic paraventricular nucleus to the spinal cord. The paraventricular nucleus innervates all rostrocaudal segments of the cord, yet the projection is not massive, allowing the trauma response of individual axons to be studies.

Immediately caudal to a T4 hemisection, axons began decreasing in number by 2 days after surgery. Ten days postoperatively, only a few axons could be found caudal to the cut; these remaining axons arose from the contralateral cord. A substantial increase in the number of stained axons was found rostral to the hemisection 3–12 weeks after surgery. In that an increase in axon number could be due to both increasing staining efficacy and sprouting, the orientation of axons in control and hemisected rats was studied. Three millimeters rostral to the hemisection, axons had a greater variance in orientation and were more likely to project medially out of the dorsolateral white matter compared with the contralateral control side. Rostral to the hemisection, a statistically significant two‐ to fourfold increase in the number of branches per axon was found in comparison to the contralateral control side. Axons were found in the dorsal white matter 4 months after surgery; in controls, immunostained axons were not found here. At all intervals after surgery, structures suggestive of growth were found, including terminal growth cones and lateral filopodia and lamellipodia extending from axons whose distal ends had been severed by hemisection. Similar structures were not found in control spinal cord. Together, these data suggest that after cord hemisection, axons from the paraventricular nucleus sprout rostral to the injury. © 1994 Wiley‐Liss, Inc.
Architectonic subdivisions of the motor thalamus of owl monkeys: Nissl, acetylcholinesterase, and cytochrome oxidase patterns
Authors: Stepniewska Iwona , Preuss Todd M. , Kaas Jon H.
Published: January 2005

As the first part of an investigation of the motor thalamus and its cortical connections in the owl monkey, a New World anthropoid primate, we studied thalamic architecture by using stains for Nissl, acetylcholinesterase (AChE), and cytochrome oxidase (CO), in order to identify subdivisions of the ventrolateral thalamic region as well as other nuclei with motor connections. Material was obtained from brains cut in the frontal, horizontal, and parasagittal planes. Our results indicate that the ventrolateral thalamic region (VL) of owl monkeys is a heterogeneous structure composed of several architectonic subdivisions that resemble divisions that have been described in macaques and other Old World anthropoids. All of these subdivisions are more readily distinguished in AChE than in Nissl or CO preparations.

The anterior part of VL, VLa (VLo of Olszewski), is characterized by clusters of medium‐sized, darkly stained neurons. VLa is also distinguished by AChE‐positive cells embedded in a matrix of neurites as well as by a characteristic dark, irregular net of blood vessels. The posterior part of VL is rather uniform cytoarchitectonically and contains large, darkly stained, and sparsely distributed neurons. However, we were able to distinguish three subdivisions of posterior VL that closely correspond to structures described by Olszewski in macaques: a principal segment, VLp (VPLo of Olszewski), a medial segment, VLx (“area X” of Olszewski), and a dorsal segment, VLd (VLc and VLps of Olszewski). In AChE, VLd is much darker than the other divisions. The distinction between VLp and VLx, which together make up the largest part of VL, is less marked, although VLp is somewhat darker and more irregular in appearance in AChE than is VLx. © 1994 Wiley‐Liss, Inc.
Early development of the optic chiasm in the gray short‐tailed opossum, Monodelphis domestica
Authors: Taylor J. S. H. , Guillery R. W.
Published: January 2005

We have studied the early development of the uncrssed retinofugal projection in the gray short‐tailed opossum. Axons that form the adult uncrossed retinofugal projection arise from the temporal crescent of the retina and reach the optic chiasm on postnatal day 7. The sites at which the uncrossed fibres segregate from the crossed fibres and the pattern of this segregation are very different from those seen in eutherian mammals. In the opossum, the uncrossed fibres segregate from the crossed fibres within the juxtachiasmatic part of the optic nerve before they have encountered either the fibres of the other eye or midline structures of the ventral diencephalon. The uncrossed fibres turn perpendicular to the axis of the nerve and grow dorsoventrally through the crossed projection to gather as a discrete bundle at the ventral edge of the nerve. The abrupt divergence of the uncrossed fibres occurs at a border between two glial cell types: the interfascicular glia that characterise the main part of the optic nerve and the radial glia of the juxtachiasmatic part of the nerve. At the ventral part of the nerve, the bundle of uncrossed fibres turns caudally across the axis of the nerve and enters the ipsilateral optic tract. When retinofugal fibres encounter the border between the interfascicular and radial glia, a very specific axonal reorganisation occurs in marsupials, and this is strikingly different from the axonal reorganisation that occurs at the same site in eutherians, where essentially all retinofugal fibres reorganise, not just the uncrossed component. We believe this to be an important example of an identified cellular element that has quite distinct axon‐guidance properties in different species. © 1994 Wiley‐Liss, Inc.
GABAA receptor α1 subunit, an early marker for area specification in developing rat cerebral cortex
Authors: Paysan Jacques , Mohler Hanns , Fritschy Jean‐Marc , Paysan Jacques , Bolz Jürgen
Published: January 2005

Changes in the expression of neurotransmitter receptors in developing cerebral cortex may be related to the functional maturation of distinct areas. In the present study, we have tested whether GABAA receptor expression in neonatal rats reflects the differentiation of cortical areas. Specifically, the α1 subunit, one of the most prevalent GABAA receptor subunits in adult cerebral cortex, is up‐regulated postnatally, suggesting a link with the establishment of inhibitory circuits. Using immunohistochemistry with a subunit‐specific antiserum, we observed a striking area‐ and lamina‐specific increase in staining for GABAA receptors containing the α1 subunit (α‐GABAA receptors), from low levels in neonates to an intense and uniform staining in adults. Already at birth, the α‐subunit immunoreactivity selectively demarcated the boundaries of certain cortical areas. In particular, the primary somatosensory (S1) and visual (V1) areas were distinctly delineated with a band of α1‐subunit immunoreactivity located in the developing layers III and IV. The staining ended abruptly at the presumptive boundaries of S1 and V1, adjacent areas being unstained at this age. Around postnatal day 3, clusters of α‐subunit positive cells were seen in layers III–IV of S1 and V1 extending their dendrites up to layer I, where they arborized profusely. In addition, the distribution of α‐GABAA receptors in S1 revealed in detail the differentiation of the barrel field during early postnatal development. Although staining was observed in all areas by postnatal day 6, differences in the laminar distribution of α‐GABAA receptors persisted for at least 1 more week. Our results provide evidence for the existence of area‐specific boundaries in neocortex of newborn rats before layers III–IV are fully differentiated and innervated by cortical afferents. Furthermore, the area‐ and lamina‐specific maturation of α‐GABAA receptor staining demonstrates the value of this marker for investigating the cytoarchitectonic differentiation of cortical areas during development. 1994 Wiley‐Liss. Inc.
Replacement of an inherited stretch receptor by a newly evolved stretch receptor in hippid sand crabs
Authors: Paul Dorothy H. , Wilson Linda J.
Published: January 2005

Primary sensory neurons that are motoneuron‐like in morphology and often nonspiking (transmit afferent signals as graded depolarizations) characterize an unusual type of stretch receptor in decapod crustaceans. Nonspiking and spiking receptors occur in similar positions at homologous joints in different species and have been presumed to be homologous, the spiking one considered „primitive.”︁ To better understand the evolutionary origin of these stretch receptors and why some are nonspiking, we examined the spiking telson‐uropod stretch receptors in the spiny sand crab Blepharipoda occidentalis (Albuneidae) and the squat lobster Munida quadrispina (Galatheidae) and compared them with the nonspiking telson‐uropod stretch receptor of the mole sand crab Emerita analoga (Hippidae). The position, morphology and responses to stretch of the sensory neurons, and the ultrastructure of the elastic strand portion of the receptor are similar in M. quadirspina and B. occidentalis, except that in B. occidentalis the receptor muscles are substantially smaller and the extracellular matrix of the elastic receptor strand is both more extensive and more organized, reminiscent of the ultrastructure of E. analoga's nonspiking receptor. We conclude that the spiking telson‐uropod stretch receptors of albuneids and galatheids are homologous. The differences in the ultrastructure of their receptor strands imply that the efficiency of coupling receptor length change to deformation of the dendritic termini increases in the order M. quadrispina < B. occidentalis < E. analoga.

The spiking and nonspiking telson‐uropod stretch receptors differ anatomically in three major respects that appear to preclude their homology. (1) The receptor strands are on opposite sides of a conserved muscle. (2) The sensory somata are in different regions of the sixth abdominal ganglion: a lateral cluster of somata for the spiking sensory neurons and two medial clusters, one anterior, one posterior, for the nonspiking sensory neurons. (3) The neuropil projections of the sensory neurons are different. We conclude that the hippid's nonspiking telson‐uropod stretch receptor evolved de novo and not by modification of the ancestral anomuran telson‐uropod stretch receptor (which Hippidae have lost). 1994 Wiley‐Liss, Inc.
Rearing with monocular lid suture induces abnormal NADPH‐diaphorase staining in the lateral geniculate nucleus of cats
Authors: Günlük Alev E. , Bickford Martha E. , Sherman S. Murray
Published: January 2005

We investigated the changes in NADPH‐diaphorase staining that occur in the lateral geniculate nucleus of cats following rearing with monocular lid suture. This staining allows visualization of the synthesizing enzyme of nitric oxide, a neuromodulator associated with plasticity. In the lateral geniculate nucleus of normally reared cats, NADPH‐diaphorase exclusively labels the axons and terminals of an input from the parabrachial region of the brainstem; no geniculate cells in the A‐laminae are labeled. Early monocular lid suture has no obvious effect on the NADPH‐diaphorase staining of parabrachial axons. However, this lid suture results in the abnormal appearance of NADPH‐diaphorase staining for geniculate somata. These cells are located primarily in the nondeprived laminae. Double‐labeling experiments indicate that these cells with abnormal NADPH‐diaphorase reactivity are Y relay cells: NADPH‐diaphorase staining is found in cells retrogradely labeled from visual cortex; it is found in cells labeled with a monoclonal antibody for CAT‐301, which selectively targets Y cells; it is not found in cells labeled with an anti‐GABA antibody, which targets interneurons. Also, NADPH‐diaphorase labeled cells are among the largest cells in the nondeprived laminae, again suggesting that they are Y relay cells. We cannot suggest a specific mechanism for this induction of NADPH‐diaphorase labeling, but it does not seem to be due to abnormal binocular competition induced by the monocular lid suture. © 1994 Wiley‐Liss, Inc.
Cytochemical characteristics of neurons in the trigeminal mesencephalic nucleus of hatchling chicks
Authors: Scott Sheryl A. , Dinowitz Seth , Terhaar Kristen , Sherlock Diane , Campbell Maurice A. , Levine Dreania
Published: January 2005

The goal of the present study was to identify cytochemical markers characteristic of muscle afferents in hatchling chicks. To this end, we stained neurons in the trigeminal mesencephalic nucleus with a variety of markers that label subsets of neurons in avian dorsal root ganglia. We found that trigeminal mesencephalic neurons are surprisingly heterogeneous in their cytochemical make‐up, expressing, to varying degrees, substance P, cholecystokinin, carbonic anhydrase, calbindin D‐28k, parvalbumin, and S‐100β. Calbindin D28k and S‐100β appeared to be expressed equally in medial and lateral divisions of the trigeminal mesencephalic nucleus. In contrast, substance P‐ and cholecystokinin‐immunoreactive neurons were more abundant in the medial division, whereas carbonic anhydrase activity and parvalbumin immunoreactivity were stronger in the lateral division. We were unable to detect met‐enkephalin, neuropeptide Y, calcitonin gene‐related peptide, vasoactive intestinal peptide, somatostatin, γ‐aminobutyric acid, or tyrosine hydroxylase in the trigeminal mesencephalic nucleus. Moreover, these neurons did not appear to bind the lectin Dolichos biflorus agglutinin. The heterogeneity of expression of markers among trigeminal mesencephalic nucleus neurons, especially between neurons in the medial and lateral divisions, suggests that these neurons are functionally diverse.
Parvalbumin‐containing GABAergic neurons in the basal ganglia output system of the rat
Authors: Rajakumar N. , Elisevich K. , Flumerfelt B. A.
Published: January 2005

The output of the basal ganglia is directed through the entopeduncular nucleus (EPN) and the substantia nigra pars reticulata (SNR) and pars lateralis (SNL), which provide a γ‐aminobutyric acidergic (GABAergic) projection to various nuclei of the thalamus and brainstem. Although many neurons within the SNR and EPN have been described as modality specific, the morphological and neurochemical similarities preclude their precise identification. In the present study, the immunocytochemical localization of parvalbumin, a calcium‐binding protein, is used in combination with axonal tracing to verify neuronal heterogeneity within the SNR, SNL, and EPN. The results reveal that the majority of neurons in all three centers contain parvalbumin. The parvalbumin‐containing neurons are distributed in the caudal two‐thirds of the EPN, the rostral part of the SNL, and the lateral two‐thirds of the entire rostrocaudal extent of the SNR, the areas involved in sensorimotor function of the basal ganglia. Moreover, the negrothalamic, nigrocollicular, and EPN‐thalamic neurons possess parvalbumin immunoreactivity, whereas the EPN‐habenular neurons are devoid of parvalbumin immunoreactivity. The results indicate a neurochemical heterogeneity within the GABAergic output neurons of the basal ganglia and suggest that the parvalbumin‐containing neurons of the SNR, SNL, and EPN are the tonically active output neurons that form a major link in the disinhibitory neuronal circuit of the basal ganglia, especially that concerned with sensorimotor function. © 1994 Wiley‐Liss, Inc.
Evidence for survival of the central arbors of trigeminal primary afferents after peripheral neonatal axotomy: Experiments with galanin immunocytochemistry and Di‐I labelling
Authors: White Fletcher A. , Hoeflinger Brian F. , Chiaia Nicolas L. , Bennett‐Clarke Carol A. , Crissman Robert S. , Rhoades Robert W.
Published: January 2005

Studies employing axoplasmic transport techniques have suggested that the central arbors of vibrissae‐related primary afferents are rapidly and permanently lost from the trigeminal (V) brainstem complex after transection of the intraorbital nerve (ION). The present study reexamined this issue using immunocytochemistry for galanin (GAL) and anterograde labelling with Di‐I to evaluate V brainstem organization in rats that sustained damage to the ION or individual vibrissae follicles in infancy or adulthood. After adult nerve damage, GAL‐positive fibers are increased in layers I and II of V subnucleus caudalis (SpC). This was apparent by 3 days after the lesion. In rats that sustained nerve damage at birth (PO), GAL immunoreactivity (IR) appeared throughout the V brainstem complex and had a patchy distribution similar to that of vibrissae‐related V primary afferents in normal rats. Increased GAL‐IR in rostral portions of the V brainstem complex was observed in rats that sustained ION damage as late as P14. Additional experiments in which nerve damage was followed by destruction of the V ganglion demonstrated that this GAL‐IR was contained in primary afferents. Damage to single vibrissa follicles or to a row of follicles produced a single patch or row of GAL‐IR terminals in the somatotopically appropriate portion of the ipsilateral V brainstem complex. Di‐I labelling in neonatally nerve‐damaged rats demonstrated that primary afferent axons filled the central territory normally innervated by this nerve and that their terminal distribution was patchy. These results suggest that the V ganglion cells that survive neonatal axotomy may retain somatotopically organized projections to the V brainstem complex for at least a limited postnatal period.
Differential physiology and morphology of motor axons to ventral longitudinal muscles in larval Drosophila
Authors: Kurdyak P. , Atwood H. L. , Stewart B. A. , Wu C.‐F.
Published: January 2005

Morphological and physiological characteristics of the two major motor axons supplying the commonly studied ventral longitudinal muscle fibers (6 and 7) of third‐instar Drosophila melanogaster larvae were investigated. The innervating terminals of the two motor axons differ in the size of their synapse‐bearing varicosities. The terminal with the larger varicosities also fluoresces more brightly when stained with the vital fluorescent dye 4‐(4‐diethylaminotyryl)‐N‐methylpyridinium iodide (4‐Di‐2‐Asp) and occupies a larger total contact area on the muscle fiber. Through selective simultaneous recording of synaptic currents from identified boutons in living preparations during elicitation of synaptic potentials, it was shown that the axon with the smaller varicosities generates a large excitatory junction potential (EJP) in muscle 6 and that the axon with the larger varicosities generates a smaller EJP. Short‐term facilitation is more pronounced for the smaller EJP. In preparations treated with 4‐Di‐2‐Asp, the fluorescence of smaller varicosities increases with stimulation that elicits the large EJPs, indicating an acitivity‐dependent entry of calcium that enhances mitochondrial fluorescence. The differences in morphology and physiology of the two axons are similar to, though less pronounced than, those observed in „phasic”︁ and „tonic”︁ motor axons of crustacens. © 1994 Wiley‐Liss, Inc.
Morphological evidence for the presence of ipsilateral inferior olivary neurons during postnatal development of the olivocerebellar projection in the rat
Authors: López‐Roman Antonio , Armengol José Angel
Published: January 2005

The presence of ipsilateral inferior olivary neurons during postnatal development of the olivocerebellar projection in the rat was investigated by two in vitro axonal tracing methods and by the axotomy of one olivocerebellar tract. The experiments were carried out before (P1), during (P5–P10) and after (P20) the period of multiple innervation of Purkinje cells by climbing fibers. According to present results: (1) ipsilateral inferior olivary neurons are distributed, on all analyzed days, throughout the entire inferior olive; (2) cell counts after axotomy experiments demonstrated that they represent a small population of inferior olivary neurons, whose number oscillated between 271 ± 30 in young animlas (pedunculotomized at P1 and killed at P7) and 26 ± 12 in older ones (pedunculotomized at P20 and killed at P40). This experiment confirmed that most of these neurons are eliminated during the regressive events that take place during normal development of the olivocerebellar projection; and (3) few ipsilateral inferior olivary neurons, however, survive at P40, but their significance is still unclear. © 1994 Wiley‐Liss, Inc.