bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of corpus callosum section on functional compensation in the posteromedial lateral suprasylvian visual area after early visual cortex damage in cats
Authors: Tong Lillian , Spear Peter D. , Kalil Ronald E.
Published: January 2005

A visual cortex lesion made in adult cats leads to a loss of direction selectivity and a loss of response to the ipsilateral eye among cells in posteromedial lateral suprasylvian (PMLS) cortex of cats. However, a visual cortex lesion made in young cats results in normal direction selectivity and normal ocular dominance in PMLS cortex. Thus cats with an early lesion demonstrate functional compensation in PMLS cortex. The present experiment determined whether the functional compensation depends upon an intact corpus callosum.

Cats received a unilateral visual cortex lesion on the day of birth (day 1) or at 8 weeks of age. When the cats were adult, the corpus callosum was sectioned and 24 hours later recordings were made in PMLS cortex ipsilateral to the visual cortex lesion. Results were compared to cats with a similar lesion and an intact corpus callosum.

In cats with a lesion made on day 1, a corpus callosum section did not affect receptive‐field properties or ocular dominance in PMLS cortex. Therefore, functional compensation is not dependent on input via the corpus callosum in these animals. However, in cats with a lesion made at 8 weeks, a corpus callosum section resulted in a decrease in the percentage of direction‐selective cells and in the percentage of cells driven by the ipsilateral eye. Despite the decrease, the percentage of direction‐selective cells still was greater than in cats with an adult unilateral visual cortex lesion. Thus, while partly dependent on callosal inputs, some functional compensation for direction selectivity remains on the basis of ipsilateral inputs. In contrast, the percentage of cells driven by the ipsilateral eye was no longer significantly different from that in cats with an adult visual cortex lesion. This suggests that functional compensation for response to the ipsilateral eye is dependent on an intact corpus callosum in cats that received a visual cortex lesion at 8 weeks of age.
The organization and mutability of the forepaw and hindpaw representations in the somatosensory cortex of the neonatal rat
Authors: Dawson Douglas R. , Killackey Herbert P.
Published: January 2005

The present study demonstrates that the primary somatosensory cortex of the rat contains a map of the entire body surface that is discernible with a routine anatomical staining technique, the succinic dehydrogenase reaction. The overall proportions of this map are relatively constant from rat to rat and very similar to those reported in previous physiological investigations (Welker: Brain Res. 26:259–275, '71, J. Comp. Neurol. 166:173–190, '76). We found 67% of the map to be related to the head of the rat, 15% to the forelimb, 14% to the trunk, and 4% to the hindlimb. Within the forelimb and indlimb representations, there is a consistent internal organization that can be related to specific peripheral structures (digits or palm pads). Further, damage to either the periphery or the nerves innervating these regions on the day of birth produces disruptions in the normal pattern, but damage on day 6 or later does not. We interpret these results as indicating that the role of the periphery in organizing central neuronal structures during development previously demonstrated for the trigeminal system extends to the entire rat somatosensory system. Comparison of the present results with physiological studies of adult cortical maps after peripheral damage suggests to us that different substrates underlie the changes reported in the adult.
Forelimb motor cortical projections in normal rats and after neonatal hemicerebellectomy: An anatomical study based upon the axonal transport of WGA/HRP
Authors: O'Donoghue Daniel L. , Kartje‐Tillotson Gwendolyn , Castro Anthony J.
Published: January 2005

Cerebral cortical projections from the forelimb motor cortex, as defined by intracortical microstimulation where movements were evoked at low current intensities (< 15μA), were examined in normal rats and in adult rats that sustained neonatal hemicerebellectomy. The distribution pattern of cortical efferent projections in normal rats generally appeared more restricted than previously described. This restricted distribution is attributed to the use of WGA/HRP as the axonal tracing method and to the electro‐physiological definition of the injection site as the motor cortex. The observed remodeling of the corticobulbar projections, seen after cerebellar lesions in the young, largely confirmed previous reports. Moreover, no alterations in the laterality of distribution in corticospinal projection were found. Aberrant corticospinal projections were sought in an effort to provide an anatomical basis to a previous description of abnormally low‐threshold ipsilateral forelimb responses evoked from the motor cortex in adult rats after neonatal cerebellar lesions. This apparent absence of corticospinal tract remodeling after neonatal hemicerebellectomy suggests that the abnormal responses are mediated by the normal corticospinal pathways. This possibility is discussed in terms of an alteration in the spinal circuits that may change the responsiveness of spinal motoneurons to a given pyramidal discharge.
Sexual dimorphism in sympathetic preganglionic neurons of the rat hypogastric nerve
Authors: Nadklhaft Irving , McKenna Kevin E.
Published: January 2005

Horseradish peroxidase (HRP) applied to one hypogastric nerve labelled sensory neurons in T11–L3 dorsal root ganglia (DRG) bilaterally and preganglionic neurons (PGN) in the spinal cord segments T13–L3. An average of 130 small DRG neurons were labelled per animal (male or female). These were concentrated in the L1 + L2 DRGs (92%). About 75% were located ipsilateral to the site of HRP application. Central projections from DRG neurons were noted throughout Lissauer's tract and in the marginal zones (medial and lateral) near the borders of Lissauer's tract. A short projection was also seen extending to the dorsolaterai funiculus.

More than 90% of the preganglionic neurons were located in segments L1 + L2. Most of these were found in the dorsal commissural nucleus (75%) and most of the remainder were located bilaterally in the intermediolateral columns. Somewhat more intermediolateral neurons were labelled on the ipsilateral side than on the contralateral side. There were a few intercalating neurons and a very few funicular cells. An average of 415 PGNs were labelled in the male animals and 110 in the females, demonstrating a strong sexual dimorphism. No dimorphism was found in the sensory components.
Histochemical identification of pallidal and striatal structures in the lizard Gekko gecko: Evidence for compartmentalization
Authors: Russchen Fokje T. , Smeets Wilhelmus J. A. J. , Hoogland Piet V.
Published: January 2005

The present study provides a description of the distribution patterns of enkephalin, substance P and dopamine immunoreactivity, and acetylcholinesterase activity in the striatum, nucleus accumbens, globus pallidus, and ventral pallidum of the Gekko gecko. The pallidal structures were identified on the basis of characteristic enkephalin and substance P immunoreactive Plexus. The globus pallidus contains a very dense enkephalin immunoreactive wooly fiber plexus and a light and less extensive substance P immune‐reactive plexus. The ventral pallidum is characterized by substance P and enkephalin immunoreactive woolly fiber plexus, which show a dense and moderate staining, respectively. The striatum and the nucleus accumbens were found to be inhomogeneous with respect to staining intensities for all four makers. Except for the enkephalin immunoreactivity distribution pattern in the striatum, the compartments that can be distinguished in material stained for these markers appear to coincide quite well.
Development of the spinal nerves in the lamprey: III. Spinal ganglia and dorsal roots in 26‐day (13 mm) larvae
Authors: Nakao T. , Ishizawa A.
Published: January 2005

Serial sections of the trunk and tail of 26‐day (13 mm) larval lampreys were examined by light and electron microscopy.

Trunk region: Spinal ganglia and ventral nerves are seen alternately along the spinal cord and the notochord in the trunk. Spinal ganglia are located medially in intermyotome spaces with intersegmental blood vessels and send “dorsal nerves” ventrally along the vessels. “Ventral nerves” are seen on the midmedial surface of each myotome. Fibers containing densecored vesicles occur in the dorsal root but not in the ventral root.

Caudal region: In the caudal one‐third of the tail the ventral nerves are formed earlier than spinal ganglia and dorsal nerves. The most caudal (primitive) ventral nerve (root) develops at the 12th myotome from the caudal end of the series of myotomes, the caudalmost ganglion being formed between the 15th and the 14th myotome in a 13‐mm larval lamprey. The intimate association of dorsolateral outflow (DLO) fibers (Nakao and Ishizawa: J. Comp. Neural 256:356–368, '87b) with neural crest cells (DO cells of Nakao and Ishizawa; ibid.) strongly suggested that these fibers play an important role as the substrate for guiding the cells to form compact cell masses as primitive spinal ganglia. Two types of cell groups are progressively distinguished in primitive spinal ganglia during development. One of them has a light round nucleus with a prominent nucleolus and a large amount of the perinuclear cytoplasm that contains abundant free ribosomes, rough endoplasmic reticulum (ER), numerous Golgi apparatuses, and dense bodies. Cells of the other type are characterized by a dense, flattened nucleus with a small amount of perinuclear cytoplasm that extends as a thin cytoplasmic sheet to surround cells of the other type as a whole, the basal lamina surrounding the whole cell mass. The former type is interpreted as neural cells and the latter satellite cells of the ganglion. Central processes of ganglionic neural cells are assumed to enter the spinal cord along DLO fibers by using them as a substrate to establish the dorsal root. Intersegmental blood vessels develop later than spinal ganglia and peripheral processes extend along the vessels.
Morphological and functional changes in the retinotectal system of the pigeon during the early posthatching period
Authors: Bagnoli Paola , Porciatti Vittorio , Fontanesi Gigliola , Sebastiani Laura
Published: January 2005

Anterograde transport of either HRP or wheat germ agglutinin‐conjugated HRP was used to study the posthatching development of the retinotectal connection in the pigeon. The functional maturation of the retinotectal system was also investigated by recording electroretinographic (ERG) and tectal evoked (TEP) responses to either flash or pattern stimuli. Two main morphological changes occurred in the retinotectal system during the first 6 days after hatching: (1) an ipsilateral retinofugal component that was present at hatching disappeared and (2) the outer tectal layers were progressively invaded by the contralateral retinofugal axons, which at hatching were limited to the stratum griseum et fibrosum superficiale of the dorsolateral tectal quadrant. During the early posthatching period, at the same developmental stage at which an ERG to unpatterned or patterned stimulation could first be recorded, a visually evoked response could be elicited in the contralateral optic tectum. Therefore, the retina and optic tectum seem to start functioning simultaneously, the limiting factor being the late maturation of photosensitive lamellae in the outer segments of the developing photoreceptors. During the first 20 days posthatching, the retinotectal system undergoes extensive development as revealed by latency and amplitude changes of the visually evoked potentials. We suggest that the pigeon visual system serves as a useful model for studies concerning visual development and plasticity.
Distribution of choline acetyltransferase‐immunoreactive neurons in the brain of a cyprinid teleost (Phoxinus phoxinus L.)
Authors: Ekström Peter
Published: January 2005

The distribution of putative cholinergic neurons in the brain of a cyprinid teleost was investigated by immunocytochemistry, with well‐characterized polyclonal antibodies to porcine choline acetyltransferase (ChAT), correlated with acetylcholinesterase (AChE) histochemistry. AChE‐positive neurons were more numerous than GhAT‐immunoreactive (ChAT‐IR) neurons. Regions with ChAT‐IR neurons generally also contained AChE‐positive ones, but regions with AChE‐positive neurons often did not contain (or contained only small numbers of) ChAT‐IR neurons. ChAT‐IR neurons were located in the brainstem cranial nerve motor nuclei, in the brainstem reticular formation, in the nucleus laterals valvulae and an adjacent subnucleus “a,” in the nucleus isthmi, and in the stratum griseum periventriculare of the tectum opticum. All neurons in these areas were AChE positive. ChAT‐IR neurons were also observed within the boundaries of the nucleus sensibilis nervi trigemini and the n. descendens nervi trigemini. The periventricular hypothalamus and the paraventricular organ, the pineal organ, and (possibly) the nucleus suprachiasmaticus also contained ChAT‐IR neurons. In these areas, AChE activity was either low or located mainly in neurons other than the ChAT‐IR ones. A small population of ChAT‐IR neurons was observed in area ventralis telencephali pars lateralis. This was the only telencephalic ChAT‐IR cell group. Furthermore, some previously unrecognized cell groups were observed. A small number of ChAT‐IR neurons, located on the dorsal aspect of the fasciculus longitudinalis medialis (caudal to n. raphe dorsalis), emitted axons that passed caudally along the raphe midline and innervated some of the large reticular neurons. Another group of ChAT‐IR neurons was observed caudal to the thalamic nucleus centralis posterior and was tentatively designed n. tractus rotundus, on the basis of the neuronal morphology. The almost Golgilike staining of some of the ChAT‐IR cell groups permitted the identification of their efferent connections and the areas covered by their dendrites.
Local circuit neurons of macaque monkey striate cortex: I. Neurons of laminae 4C and 5A
Authors: Lund Jennifer S.
Published: January 2005

A study has been made, using Golgi preparations, of the organization of neurons with smooth or sparsely spined dendrites, here called local circuit neurons, of the macaque monkey primary visual cortex. Since these neurons include those responsible for inhibitory circuitry of the cortex, a better understanding of their anatomical organization is essential to concepts of functional organization of the region. This account describes those neurons found with cell body and major dendritic spread within the thalamic recipient zone of lamina 4C and its border zone with lamina 5A. The neurons are grouped firstly in terms of in which laminar division the soma occurred– 4CβbT, 4CβaL or the border zone of 5A‐4CβbT–and secondly, into varieties on the basis of the interlaminar projection patterns of their axons. Most, if not all, of the local circuit neurons of these divisions have interlaminar axon projections as well as an arbor local to their cell body and dendritic field. These interlaminar projections are highly specific, targeting from one to five laminar divisions depending on the variety of neuron; on this basis 17 varieties of local circuit neuron are described. While the number of varieties appears dauntingly large in terms of understanding the functional circuitry of the region, the clear‐cut organization of the interlaminar links may provide clues as to the information processing that concerns each neuron. The local circuit neuron axon projections can be related to a wealth of information already available concerning the laminar organization of afferent axons and efferent cell groups, the organization of spiny neuron intrinsic relays (presumed to be excitatory), and physiological properties of different laminar divisions. It is hoped that the information derived from this study can serve as a guide for correlated physiological‐anatomical studies on single cells of the region.
Vestibular nuclear complex in the guinea pig: A cytoarchitectonic study and map in three planes
Authors: Gstoettner W. , Burian M.
Published: January 2005

Cytoarchitectonic and fiberarchitectonic criteria were used in the preparation of a detailed map illustrating the vestibular nuclear complex of the guinea pig. The brainstems used for this study were serially cut at 16 μm in the transverse, the sagittal, or the horizontal plane. The sections were studied after being stained alternately with a combined cell and fiber staining method and a Nissl stain.

The basic Cytoarchitectonic features of the four main vestibular nuclei, their extent, as well as their relationship to the surrounding structures are described. Additionally, the location, topographical features, and the cytoarchitecture of the small groups (f,g,l,x,y,z) associated with the vestibular nuclei are reported. Group f is especially well developed and easily distinguishable in the guinea pig. Furthermore, a hitherto undescribed cell cluster found dorsal to the dorsal border of the superior vestibular nucleus is presented. The results and especially the differences from the descriptions of other species are discussed.
A role of insular cortex in cardiovascular function
Authors: Ruggiero David A. , Mraovitch Sima , Granata Antonio R. , Anwar Muhammad , Reis Donald J.
Published: January 2005

We sought to determine whether the insular cortex contributes to the regulation of arterial blood pressure (AP). Responses to electrical and chemical stimulation of the cortex were studied in the anesthetized, paralyzed, and artificially ventilated Sprague‐Dawley rat. The insular cortex was initially defined, anatomically, by the distributions of retrogradely labeled perikarya following injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) into the nucleus tractus solitarii (NTS). Injections of WGA‐HRP into the insular cortex anterogradely labeled terminals in cardiopulmonary and other divisions of the NTS and confirmed projections revealed by retrograde tracing experiments.

Electrical stimulation of the insular cortex elicited elevations of AP (≤50 mm Hg) and cardioacceleration (≤ 40 bpm). The locations of the most active pressor sites corresponded closely to the locations of retrogradely labeled cells in layer V of granular and posterior agranular areas of the insular cortex (areas 14 and 13) and the extreme capsule. Maximal pressor responses were obtained at a stimulus intensity of three to five times threshold current of 20–30 μA. Responses elicited mostly with higher‐threshold currents were also mapped in areas 2a and 51b and the claustrum and within the corpus callosum. Unilateral injections into the insular pressor area of the excitatory amino acid monosodium glutamate (L‐Glu; 0.05 nmol to 10 nmol) or the rigid structural analogue of L‐Glu, kainic acid (KA) (0.4 nmol) (which specifically excite perikarya), caused topographically specific elevations in AP and tachycardia.

During the course of the anatomical transport studies, new findings were obtained on the organization and characteristics of the cortical innervation of the NTS and the nucleus reticularis parvocellularis. Topographic relationships between the cortex and the NTS were organized in a more complex manner than previously thought. Cells projecting to caudal cardiopulmonary segments of the NTS were fewer and generally located ventrally and caudally and in a more restricted area than cells projecting rostrally or to the parvicellular reticular formation. Anterograde transport data revealed new presumptive terminal fields in dorsolateral, ventral, periventricular, and commissural regions of the NTS, including an area overlapping the terminal field of the aortic baroreceptor nerve.

We conclude that (1) neurons within an area of the insular cortex projecting to multiple brainstem autonomic nuclei, including a region of the NTS innervated by baroreceptor afferents, increase arterial blood pressure and heart rate; (2) cortical projections to the NTS are widespread but limited to discrete subdivisions of the nucleus; (3) a comparatively small percentage of cortical neurons project to caudal versus rostra1 levels of the NTS; and (4) autonomic pathways from the insular cortex may regulate circulatory and possibly other autonomic functions.
Golgi analyses of dendritic organization among denervated olfactory bulb granule cells
Authors: Greer Charles A.
Published: January 2005

In the vertebrate olfactory bulb, the primary projection neurons, mitral and tufted cells, have reciprocal dendrodendritic synapses with respective subpopulations of anaxonic interneurons called granule cells. In the neurological murine mutant Purkinje Cell Degeneration (PCD) all mitral cells are lost during early adulthood. As a consequence, a subpopulation of granule cells is deprived of both afferent input and efferent targets. The effect of this event, on the morphology and sublaminar distribution of granule cells was studied with light microscopic Golgi procedures in affected homozygous recessive PCD mutants and normal heterozygous littermate controls. In the control mice, a minimum of three subpopulations were identified predominantly on the basis of the topology of apical dendrites and their spinous processes within the external plexiform layer (EPL) of the olfactory bulb: type I had dentrites extending across the full width of the EPL and a homogeneous distribution of spines; type II had dendritic arbors confined to the deeper EPL; type III had apical dendrites that arborized extensively within the superficial EPL with no arbors or spines present in the deeper EPL. Prior studies suggest that type II cells form connections with mitral cells; type III cells form connections with tufted cells; and type I cells may integrate information from both populations of projection neurons. In the mutant PCD mice, the classification of subpopulations of granule cells proved difficult due to a compression of dendritic arbors within the EPL. Dendritic processes followed a more horizontal tangent relative to the radial orientation seen in control mice. The length of dendritic branches was reduced by approximately 20% with a corresponding decrease in the number of spines. The density of spines ( #/1 m̈m of dendrite) was constant in both controls and mutants at approximately 0.21. Truncation of the dendrites in the PCD mutants appeared to occur at terminal portions because the number of dendritic bifurcations was equal in both groups of mice. The data are discussed in terms of subpopulations of granule cells in the mouse olfactory bulb, the sublaminar organization of olfactory bulb circuits, and the capacity for survival and plasticity in the reciprocal dendrodendritic circuits mediated by the granule cell spines.
Neurogenesis in the vocalization pathway of Xenopus laevis
Authors: Gorlick Dennis L. , Kelley Darcy B.
Published: January 2005

We examined possible contributions of neurogenesis to sex differences in the vocalization pathway of the South African clawed frog, Xenopus laevis. Birthdates of neurons were obtained from autoradiograms of animals receiving tritiated thymidine from gastrulation through 1 month after metamorphosis. Thymidine availability studies showed that 80% of the [3H]‐thymidine injected into embryos and tadpoles was incorporated into the DNA of dividing cells within 3 hours. We observed 3 patterns of neurogenesis: late‐short, a short burst of proliferation occurred late in development in the anterior preoptic area, the ventromedial nucleus of the thalamus, and the pretrigeminal nucleus of the dorsal tegmental area of the medulla; protracted‐bimodal, a prolonged period of proliferation with an early and a late peak in the number of labeled cells occurred in the ventral striatum and in the ventrolateral and posterior nuclei of the thalamus; protracted‐unimodal, a prolonged period of proliferation with a single early peak occurred in the inferior reticular formation and in the medial and lateral nucleus IX‐X (containing laryngeal motor neurons). There were no differences between sexes in the number of tritiated thymidine labeled cells in any nucleus. The difference in nucleus IX‐X neuron number in adults does not appear to result from sex differences in the proliferation of these cells during development. Since neurons in the vocalization pathway do not exhibit androgen receptors until after neurogenesis is complete, we also conclude that androgen probably does not regulate the genesis of these cells.
Spinocerebellar projections from the thoracic cord in the cat, as studied by anterograde transport of wheat germ agglutinin‐horseradish peroxidase
Authors: Yaginuma Hiroyuki , Matsushita Matsuo
Published: January 2005

The projection fields of the spinocerebellar tracts arising from thoracic segments were studied by the anterograde transport of wheat germ agglutinin bound to horseradish peroxidase (WGA‐HRP) in the cat.

Following injections of WGA‐HRP into upper and middle thoracic segments, labeled mossy fiber terminals were seen in all lobules of the anterior lobe, lobules VI, VIII, and IX, sublobule VIIb, the paramedian lobule, medial parts of the dorsal paraflocculus, crus I, crus II, and the simple lobule. In the anterior lobe labeled terminals in sublobules IIb‐Vb accounted for about 50–60% of the total labeled terminals, of which about 14–18% were present in lobule III and 11–13% were present in lobule IV. The labeled terminals were concentrated within 1.0–1.5 mm from the midline in the vermal region, accounting for about 45–75% of the total in each sublobule. Following injections into lower thoracic segments, labeled terminals tended to distribute more numerously in the lateral part of the vermis and the intermediate region. In the posterior lobe about 5% of the total labeled terminals were distributed in lobules VI and VIII, respectively, and about 16–23% were in the paramedian lobule (mainly sublobules B and C). Cases with injections preceded by a lateral cordotomy have shown that about 65% of the total labeled terminals in each lobule of the anterior lobe were distributed ipsilaterally and 35%, contralaterally. In the paramedian lobule the labeled terminals were distributed predominantly ipsilaterally.

Projection fields in the horizontal plane were reconstructed from a series of transverse sections through each lobule. In lobules III and IV the labeled terminals were distributed in nine areas: areas 1–4 in the vermis and areas 5–9 in the intermediate‐lateral regions. The two medial areas 1 and 2 were located within 0.5 mm from the midline in zone A1 of Voogd and area 3 appeared to be located in zone A2. Area 4 was located between 0.75 and 1.5 mm in the medial part of zone B. These areas extended longitudinally in the middle part of the apicobasal extent. The five areas in the intermediate‐lateral regions were localized in the basal part of the lobule: area 5 in zone C1, areas 6–8 in zones C2 and C3, and area 9 in zone D. Some of these projection areas were identified also in lobules I, II, and V. In sublobule Villa four distinct longitudinal areas containing labeled terminals were found in the middle part of the apicobasal extent. In the paramedian lobule labeled terminals were distributed in ill‐defined longitudinal areas in the medial and lateral parts of sublobules B (the posterior part) and C (the copular part).
Autoradiography of mossy fiber terminals in the fastigial nucleus of the cat
Authors: van der Want J. J. L. , Gerrits N. M. , Voogd J.
Published: January 2005

Terminal boutons of mossy fiber collaterals in the fastigial nucleus originating from the nucleus reticularis tegmenti pontis, the bulbar reticular formation, and the medial vestibular nucleus were studied with high‐resolution autoradiography in order to examine their ultrastructural features and synaptic relations. Labeled mossy fiber boutons ranged in size from 0.5 to 5 μm in diameter, and they all contained clear and spherical vesicles in an electron‐lucent matrix, mitochondria, and some fine tubular elements. These boutons form asymmetric synapses with dendritic profiles of different sizes. No evidence was found for mossy fiber termination on the soma of fastigial neurons. Two types of mossy fiber terminals were distinguished on the basis of the aggregation of synaptic vesicles: one type with clustered vesicles and one type with densely packed vesicles, occurring in equal number from all sources. Furthermore, the applicability of the congruity hypothesis is confirmed for the general identification of terminals.
Displaced ganglion cells in the retina of the rat
Authors: Linden Rafael
Published: January 2005

The distribution, laterality of projection, and perikaryal sizes of displaced ganglion cells (DGCs) were examined in whole‐mounted retinae after massive unilateral injections of horseradish peroxidase along the optic tract in pigmented rats. The DGCs were found predominantly in the lower temporal periphery of the retina. Nearly all DGCs labeled had contralaterally projecting axons. The sizes of the labeled DGCs spanned the range of ordinary ganglion cells, but few middle‐sized DGCs were labeled. The results support the hypothesis that displaced ganglion cells are late‐developing neurons that do not complete their migration toward the ganglion cell layer during retinal histogenesis.
Transneuronal transport of wheat germ agglutinin‐conjugated horseradish peroxidase into trigeminal interneurones of the rat
Authors: Appenteng K. , Girdlestone D.
Published: January 2005

Intramuscular injections of either horseradish peroxidase (HRP) or wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) were made into the masseter muscle of rats. Both tracers labeled primary sensory neurones in the V mesencephalic nucleus, motoneurones in the V motor nucleus, and some motoneurones in die facial motor nucleus. WGA‐HRP labeled additional neurones in the V main sensory nucleus and the rostral pole of the V nucleus oralis. These were classed as interneurones because they lay in areas outside those known to contain either first‐order afferent or motoneurone somata. We argue that these were labeled by retrograde transport of tracer because they lay close to the V motor nucleus, and from some of them processes could be followed into the region of the V motor nucleus.
The connection of the peripeduncular area studied by retrograde and anterograde transport in the rat
Authors: Arnault Patricia , Roger Michel
Published: January 2005

Lying just ventral to the medial geniculate nucleus and dorsal to the cereberal peduncle, the peripeduncular area (PPA) seems to be implicated in the expression of several sexual reflexes in rodents. The aim of the present investigation was to establish the organization of the afferent and efferent projections of the rat's PPA in an attempt to provide a neural substrate corresponding to the behavioral observations. Based on both retrograde and anterograde transport methods, our results suggest that the PPA: (1) receives its main afferent projections from the insulotemporal cortex, basal ganglia, ventromedial and posterior hypothalamic nuclei, zona incerta, inferior colliculus, intermediate and deep layers of the superior colliculus, central gray, cuneiform nucleus, laterodorsal tegmental nucleus, and dorsal nucleus of the lateral leminiscus and, (2) projects essentially to the basal ganglia, ventromedial hypothalamic nucleus, central gray, cuneiform and pedunculopontine nuclei, deep layers of the superior collic‐ulus, inferior colliculus, and dorsal and ventral nuclei of the lateral lemniscus. These findings, indicating that the PPA is connected with the auditorry, motor, and limbic systems and with nonspecific diencephalic and mesencephalic centers, are in agreement with the notion that in rodents this area might play a role in the female sexual receptivity (as expressed by lordosis display or ultrasound production) or male mounting behavior.
Vasoactive intestinal polypeptide cerebrospinal fluid‐contacting neurons of the monkey and cat spinal central canal
Authors: Lamotte Carole C.
Published: January 2005

Neurons immediately adjacent to the central canal were demonstrated in the cat and monkey to be immunoreactive for the peptide vasoactive intestinal polypeptide (VIP), by means of the peroxidase antiperoxidase method. Most of the cells were found in the thoracic and sacral segments, although a few were present at each level. The thoracic neurons were multipolar and either ependymal or subependymal; they usually had a large, thick dendrite that was oriented radially toward the center of the central canal; this dendrite penetrated through the ependymal layer and ended as a large, fringed podlike process (4–5‐μm diameter) along the canal surface in contact with the cerebrospinal fluid (CSF). From the basal surface of the thoracic cell arose several small dendrites and a varicose axon. A few of the thoracic VIP neurons also contained two nuclei. In the sacral cord, the VIP neurons that lie along the central canal were of several types. They were round or multipolar and were either subependymal, within the ependyma, or supraependymal. Many had long dendrites and thin varicose axons stretching for long distances parallel to the cord surface. Other VIP neurons were smaller cells with short, highly branched, varicose processes. Most prominent in the sacral cord of the cat was a massive intricate network of intensely labelled processes extending in parallel along the canal surface. This network contained thick dendrites, highly varicose axons, and small neurons. Electron microscopy demonstrated VIP axons and varicosities containing small round clear vesicles and dense core vesicles. These processes were in desmosomal contact with ependymal cells and in direct contact with the CSF space. VIP processes were also found along the pial surface of the spinal cord at each level. In some cases single axons and bundles of axons arising from the area around the central canal could be traced to terminal fields along the ventral median fissure and the ventral and ventral lateral surface. In summary, the cat and monkey spinal canal is richly innervated by VIP neurons with elaborate processes in contact with the cerebrospinal fluid; further, some of these neurons may also extend axons to the ventral surface of the spinal cord. In these aspects, these cells resemble CSF‐containing neurons previously described in lower species.
Identification of acetylcholinesterase‐reactive neurons and neuropil in neostriatal transplants
Authors: Walker Paul D. , Chovanes George I. , McAllister James P.
Published: January 2005

To identify and describe neurons in neostriatal transplants that synthesize acetylcholinesterase (AChE), the present study has utilized the irreversible AChE inhibitor diisopropylfluorophosphate (DFP) combined with AChE histochemistry. Dissociated suspensions of tissue taken from the striatal ridge of embryos at 14 days of gestation were transplanted into the neostriatum of adult rats 5 days after intrastriatal kainic acid lesions.

Two types of AChE neurons have been identified in transplants treated with DFP. One type resembled the large intensely reactive AChE neuron that is thought to be a cholinergic interneuron of the normal neostriatum. The other type resembled smaller, less reactive AChE neurons of the neostriatum, as well as medium‐sized, lightly reactive AChE neurons of the globus pallidus. Qualitative observations suggest that these less reactive AChE neurons were more numerous in transplants compared to the normal neostriatum. Both AChE neuronal types were found in segregated clusters throughout the grafts. Transplants processed for AChE histochemistry without DFP treatment contained two types of AChE neuropil. Dark areas of AChE neuropil similar in intensity to the normal neostriatum were found between larger areas of lighter AChE neuropil.

These results demonstrate that neostriatal transplants contain AChE neurons and suggest that these neurons contribute to the AChE reactivity within the graft.
Classes of neurons in relation to the laminar organization of the lateral geniculate nucleus in the tree shrew, Tupaia belangeri
Authors: Saini K. , Kretz R. , Rager G.
Published: January 2005

We used the rapid Golgi and horseradish peroxidase (HRP) techniques to study the dendritic spread of relay neurons in functionally distinct laminae of the tree shrew dorsal lateral geniculate nucleus (LGNd). On the basis of their dendritic spread in relation to laminar and interlaminar zones, we describe three classes of relay neurons. (1) Unilaminar neurons with multipolar radiate, bitufted, and intermediate types of dendrites. Dendrites of these neurons are confined to one lamina only, but also can have some of their segments in adjacent interlaminar zones. (2) Multilaminar neurons with multipolar radiate, bitufted, and intermediate types of dendrites. Independent of the site of their cell bodies in a laminar or interlaminar zone, these neurons spread their dendrites over two or more laminae. (3) Interlaminar neurons whose cell bodies and dendrites are confined to a single interlaminar zone.

Unilaminar neurons are found in all the laminae. In the medial three laminae, they are more of the radiate type, whereas in laminae 4 and 5 their dendrites tend to be more of a tufted nature. Lamina 6 shows a preponderance of the elongated bitufted type. Multilaminar neurons, although less common as compared to the unilaminar, are also observed in all the laminae. Some neurons have their dendrites confined to an interlaminar zone. By retrograde transport of HRP injected into the visual cortex, we have shown that these neurons are, in fact, relay neurons. In addition to relay neurons, there are small interneurons with “axoniform” dendrites and an unmyelinated axon whose arborization is confined within the limits of the neuron's dendritic spread. Neurons of this type are not labeled with HRP injected into the visual cortex.

We conclude that although each lamina is functionally specialized by input from ipsilateral or contralateral retina and by segregation of neurons responding to on or off stimuli, some multilaminar neurons can be found in each lamina. Thus, laminar as well as interlaminar zones contain a class of neurons that could provide a cross‐talk between the functionally specialized laminae. Most relay neurons in all the laminae, however, confine their dendrites to their home lamina. Thus, the dendritic architecture of relay neurons allows for processing of information both within channels and between channels.
Noradrenergic innervation of serotoninergic neurons in the myenteric plexus
Authors: Gershon Michael D. , Sherman Diane L.
Published: January 2005

The monoaminergic innervation of the guinea pig small intestine was investigated to determine if there is an anatomical basis for the hypothesis that serotoninergic and noradrenergic neurons physiologically interact in the enteric nervous system. Initial rates of uptake of tritiated 5‐hydroxy‐tryptamine (3H‐5‐HT) or norepinephrine (3H‐NE) by segments of guinea pig small intestine were measured in order to estimate the regional density of the serotoninergic and noradrenergic innervation. No change was found in the uptake of 3H‐5‐HT as a function of distance between duodenum and ileum, whereas the relative uptake of 3H‐NE declined. The pattern of serotoninergic elements demonstrated radioautographically was compared with that obtained by visualizing 5‐HT immunoreactivity. Both methods revealed that a small number of serotoninergic neurons, located in 35.3% ± 1.5% of myenteric ganglia, give rise to many fibers that form thick bundles in interganglionic connectives. Moreover, there was a pronounced heterogeneity in the serotoninergic innervation of individual myenteric neurons and ganglia. In material fixed with aldehydes and postfixed with NaMnO4, noradrenergic axon terminals were identified by their characteristic small dense‐cored vesicles. Following incubation with 3H‐NE only terminals with small dense‐cored vesicles were radioautographically labeled, confirming that these terminals are noradrenergic. When 3H‐5‐HT was substituted for 3H‐NE, noradrenergic terminals were not labeled, showing that nonspecific uptake of 3H‐5‐HT into noradrenergic axons did not occur in the presence of 5‐hydroxydopamine. The combination of aldehyde‐NaMnO4 fixation with the radioautographic localization of 3H‐5‐HT thus permitted the simultaneous identification of serotoninergic and noradrenergic neural elements. Serotoninergic varicosities were found to differ from noradrenergic varicosities in the size, appearance, and packing density of their synaptic vesicles. In addition, recognizable but rudimentary pre‐ and postsynaptic membrane specializations were associated with serotoninergic but not noradrenergic varicosities. Most serotoninergic neuronal cell bodies were contacted both by serotoninergic synapses and noradrenergic varicosities. Similar appositions of noradrenergic varicosities with nonserotoninergic neurons appeared to be rare. In view of earlier observations that sympathetic nerves affect the release of 5‐HT from stimulated enteric serotoninergic neurons, it seems likely that the noradrenergic appositions with serotoninergic neurons are the anatomical substrate for this effect. The strategic and possibly unique innervation of serotoninergic neurons by noradrenergic sympathetic postganglionic fibers is consistent with the hypothesis that the regulation of the activity of serotoninergic neurons is involved in central modulation of intestinal motility.
Choline acetyltransferase‐immunoreactive neurons and terminals in the rat septal complex: A combined light and electron microscopic study
Authors: Bialowas Jacek , Frotscher Michael
Published: January 2005

A monoclonal antibody against choline acetyltransferase (ChAT), the acetylcholine synthesizing enzyme, was used to determine the morphological characteristics of cholinergic neurons and axon terminals within the rat septum. Light microscopy revealed numerous large fusiform or multipolar ChAT‐immunoreactive neurons in the medial septal nucleus/diagonal band complex (MSDB). In contrast, virtually no immunostained cells were found in the lateral septum (Nc. septalis dorsalis and Nc. septalis lateralis). Fine immunostained fibers were most abundant close to the midline in the MSDB mainly following an ascending course. A few thin ChAT‐immunoreactive fibers and terminallike pericellular punctate stuctures were observed in the inner part of the dorsal septal nucleus.

Electron microscopy of ChAT‐immunoreactive neurons revealed large cell bodies rich in cytoplasmic organelles. The cell nuclei regularly exhibited multiple invaginations of the nuclear membrane. Only rarely were terminals found that established synaptic contacts on the cell bodies of immunostained neurons. In contrast, numerous terminals formed synaptic contacts on immunoreactive dendrites.

ChAT‐immunopositive terminals were studied in thin sections from the MSDB and from the dorsal septal nucleus. In both regions they appeared as heavily immunostained vesicle‐filled boutons that established symmetric and asymmetric synaptic contacts. In the dorsal septal nucleus immunostained terminals often showed a basketlike arrangement around immunonegative cell bodies.

Our fine structural study provides evidence that cholinergic neurons in the MSDB are similar to cholinergic neurons in the basal nucleus and neostriatum, which have been described by other investigators. The presence of cholinergic synopses in the septal complex indicates that this region not only contains cholinergic projection neurons, but receives a cholinergic input itself.
Descending projections from the superior olivary complex to the cochlear nucleus of the cat
Authors: Spangler Kevin M. , Cant Nell B. , Henkel Craig K. , Farley Glenn R. , Warr W. Bruce
Published: January 2005

Subdivisions of the cochlear nuclear complex give rise to a number of discrete projections to certain cell groups of the superior olivary complex and also received substantial descending projections from the periolivary nuclei. In the present study, we sought to determine by means of retrograde transport of horseradish peroxidase (HRP), and anterograde transport of radiolabeled protein, if the periolivary nuclei give rise to discrete projections to the various subdivisions of the cochlear nuclear complex. Following medium to large injections of HRP into the cochlear nucleus, irrespective of location, labeled cells were found in all periolivary nuclei bilaterally. In every case more than 40% of the labeled cells were found in the lateral nucleus of the trapezoid body on the same side and the ventral nucleus of the trapezoid body of both sides. Other periolivary nuclei contributing more than 5% of the total number of cells in individual cases were the contralateral lateral nucleus of the trapezoid body and the ipsilateral anterolateral and dorsal periolivary nuclei. Injections of tritiated leucine into periolivary nuclei gave rise to axonal labeling to the trapezoid body and the dorsal acoustic stria, usually bilaterally, and to terminal labeling that was widely distributed within the cochlear nuclear complex. In several cases with small injections, particularly in the lateral nucleus of the trapezoid body, the projections from the periolivary nuclei to the anteroventral and dorsal cochlear nuclei connected areas described as having similar best‐frequency representation. The autoradiographic data corroborated the main results from the HRP experiments and provided additional information permitting these conclusions: (1) the projections from the periolivary nuclei to the cochlear nuclear complex are organized tonotopically, at least in part; (2) each periolivary nucleus (and perhaps individual cells), projects widely throughout the cochlear nuclear complex; (3) the pattern of termination of projections from different periolivary nuclei to a given region of the cochlear nuclear complex are similar, as seen in autoradiograms, and (4) the lateral and dorsal periolivary nuclei project mainly ipsilaterally, while the medial periolivary nuclei project bilaterally with a contralateral bias. The magnitude of these projections and their widespread distribution within the cochlear nuclear complex would suggest an important role for the descending projections in the normal functioning of the cochlear nucleus.