bluuebunny/crossref_metadata_2025 huggingface dataset:
Monoaminergic, peptidergic, and cholinergic afferents to the cat facial nucleus as evidenced by a double immunostaining method with unconjugated cholera toxin as a retrograde tracer
Authors: Fort Patrice , Sakai Kazuya , Luppi Pierre‐Hervé , Salvert Denise , Jouvet Michel
Published: January 2005

Using a sensitive double immunostaining technique with unconjugated cholera‐toxin B subunit as a retrograde tracer, the authors determined the nuclei of origin of monoaminergic, peptidergic, and cholinergic afferent projections to the cat facial nucleus (FN). The FN as a whole receives substantial afferent projections, with relative subnuclear differences, from the following areas: (1) the perioculomotor areas, the contralateral paralemniscal region, and the mesencephalic reticular formation dorsal to the red nucleus; (2) the ipsilateral parabrachial region and the nucleus reticularis pontis, pars ventralis; and (3) the nuclei reticularis parvicellularis, magnocellularis, ventralis, and dorsalis of the medulla.

In addition, the present study demonstrated that the lateral portion of the FN receives specific projections from the contralateral medial and olivary pretectal nuclei and the ipsilateral reticular formation of the pons. It was also found that the FN receives: (1) serotoninergic inputs mainly from the nuclei raphe obscurus, pallidus, magnus, and the caudal ventrolateral bulbar reticular formation; (2) catecholaminergic afferent projections from the A7 noradrenaline cell group located in the Kölliker‐Fuse, parabrachialis lateralis, and locus subcoeruleus nuclei; (3) methionin‐enkephalin‐like inputs originating in the pretectal complex, the nucleus paragigantocellularis lateralis and the caudal raphe nuclei; (4) substance P‐like afferent projections mainly from the Edinger‐Westphal complex and the caudal raphe nuclei; and (5) cholinergic afferents from an area located ventral to the nucleus of the solitary tract at the level of the obex.

In the light of these anatomical data, the present report discusses the physiological significance of FN inputs relevant to tonic and phasic events occurring at the level of the facial musculature during the period of paradoxical sleep in the cat.
Connections of indoleamine‐accumulating cells in the rabbit retina
Authors: Sandell Julie H. , Masland Richard H. , Raviola Elio , Dacheux Ramon F.
Published: January 2005

To study the connections of the neurons of the rabbit retina that accumulate indoleamines, we injected 5,7‐dihydroxytryptamine into the vitreous body. It accumulated within a subset of amacrine cells and could be visualized there by aldehyde‐induced fluorescence. The fluorescent labeling was photoconverted to an insoluble, osmiophilic product by irradiation in the presence of diaminobenzidine, and the tissue was examined by electron microscopy. Preservation of the structure of the tissue after photoconversion was satisfactory and the dendrites of the indoleamine‐accumulating cells could easily be identified. They form a dense plexus near the junction of the inner plexiform and ganglion cell layers, where they exhibit large synaptic endings that occupy a substantial fraction of the surface of rod bipolar terminals. The dendrites of the indoleamine‐accumulating cells receive input from rod bipolars at dyad synapses, where the other postsynaptic partner is a dendrite of a narrow‐field, bistratified amacrine cell; in addition, they receive amacrine cell input throughout the inner plexiform layer. The only outputs we observed are reciprocal synapses onto the rod bipolar endings. Thus, these amacrine cells appear to exert an important effect on the transmission of scotopic information through the retina.
Synaptic organization of enkephalinlike‐immunoreactive amacrine cells in the goldfish retina
Authors: Watt Carl B.
Published: January 2005

Immunoelectron microscopy was used to examine the synaptic organization of enkephalinlike‐immunoreactive amacrine cells in the goldfish retina. Enkephalin‐immunostained processes sometimes contained dense‐cored vesicles (115–145 nm) in addition to a generally homogeneous population of small, round, clear synaptic vesicles. A total of 194 synaptic relationships were observed that involved the immunostained processes of enkephalin‐amacrine cells. The large majority of these were observed in sublayer 5 of the inner plexiform layer. In greater than 95% of the synaptic relationships, the enkephalin‐immunostained profile served as the presynaptic element. In 58.8% of these relationships, enkephalin processes synapsed onto amacrine cell processes, while 30.4% of their synapses were onto processes that lacked synaptic vesicles. They also occasionally formed synaptic contacts (6.7%) onto the somas of cells located either in the inner nuclear or in the ganglion cell layers. Enkephalin profiles received synaptic input only from amacrine cells (4.1%), while no direct synaptic interaction was observed between enkephalin processes and bipolar cells. However, in sublayer 1, enkephalin profiles were found to synapse onto amacrine cell processes that were presynaptic to bipolar cell terminals. In the proximal inner plexiform layer, enkephalin processes were presynaptic to amacrine cell processes that as a group surrounded and sometimes provided synaptic input to extremely large and round bipolar cell endings.
Callosal connections of the somatic sensory areas II and IV in the cat
Authors: Barbaresi P. , Bernardi S. , Manzoni T.
Published: January 2005

The homotopic and heterotopic callosal connections in the forelimb representations of the second (SII) and fourth (SIV) somatic sensory areas of cats were investigated by means of the axonal transport of horseradish peroxidase (HRP) in conjunction with microelectrode recording. The tracer was injected in the electrophysiologically identified hand and/or digit zone of SII (six cats) or SIV (four cats). The homotopic area in the contralateral hemisphere was explored with microelectrodes in five animals (three injected in SII and two in SIV) to map neuronal receptive fields. The aim was to correlate in the same experimental case the topography of labelled callosal neurons with the physiological map of the forelimb. Labelled cells and recording sites were plotted on planar maps reconstructed with the aid of a computer from serial coronal sections from the anterior ectosylvian gyrus.

After SII injections, labelled callosal neurons were observed throughout the forelimb representation in the contralateral area, but in the tangential plane their distribution was uneven. Each somatotopic zone composing the forelimb map, that is, the arm, hand, and digit zones, contained several subzones in which callosal neurons were either dense or rare. Microelectrode explorations showed that receptive fields mapped from callosal and relatively acallosal subzones representating the same body part were similar in extent and location. After SIV injections, labelled callosal neurons were observed throughout the forelimb and proximal body representation of the contralateral area. Although slight regional variations in the density of labelled cells were apparent, no subzones bare of callosal labelling were observed in SIV. In both SII and SIV, callosal neurons were concentrated mainly in layer III, but a significant number was also evident in the infragranular layers. After HRP injections in the digit zone of SII or SIV, labelled cell bodies were also observed in heterotopic areas of the contralateral hemisphere. Most of these neurons were clustered in the medial bank of the coronal sulcus and in two other heterotopic cortical regions lying, respectively, in the anterior suprasylvian sulcus and in the lateral branch of the ansate sulcus. Some callosal cells interconnecting SII and SIV were also labelled. The results show that the distal forelimb zones in SII and SIV are callosally connected with the respective homotopic zones and with several somatosensory fields located heterotopically in the contralateral hemisphere.
GABA‐immunoreactive neurons and terminals in the lateral cervical nucleus of the cynomolgus monkey
Authors: Broman Jonas , Blomqvist Anders
Published: January 2005

An antiserum against the inhibitory transmitter substance γ‐aminobutyric acid (GABA) was used to investigate the distribution of GABAergic nerve terminals and cell bodies in the lateral cervical nucleus (LCN) of the cynomolgus monkey. Light microscopic immunohistochemistry demonstrated GABA‐immunoreactive puncta, suggestive of nerve terminals, scattered throughout the LCN. The terminal‐like profiles are often present along the somata of unlabeled neurons, but most are located in the neuropil. GABA‐immunoreactive neurons are present in the LCN, but constitute a very small number of the LCN neurons. Electron microscopy showed that the GABA‐positive neurons are small with a relatively large nucleus. They are contacted by few somatic boutons. Numerous GABA‐immunoreactive terminals containing densely packed round to oval synaptic vesicles were also found. Most GABA‐positive terminals make synaptic contact with dendrites, but synapses with cell bodies are also present. Synaptic contacts between labeled and unlabeled terminals were not observed. Some GABA‐positive terminals make contact with GABA‐positive neurons.

The present findings suggest that GABA is a major inhibitory transmitter substance in the LCN of the monkey. However, in comparison with other somatosensory relay nuclei, there are few GABA‐immunoreactive neurons in the LCN. This may imply tha the GABA‐positive neurons branch extensively in the LCN or that an extrinsic source of GABAergic input exists.
Neurofilament phosphorylation in neuronal perikarya following axotomy: A study of rat spinal cord with ventral and dorsal root transection
Authors: Mansour H. , Bignami A. , Labkovsky B. , Dahl D.
Published: January 2005

Rat spinal cord was stained by indirect immunofluorescence with 11 neurofilament monoclonal antibodies that recognize phosphorylated epitopes. All monoclonals were axon‐specific in this location. The large motoneurons containing bundles of neurofilaments did not stain and the pattern remained unchanged after transection of the sciatic nerve in the thigh. With nine monoclonals, stained motoneurons were observed in the ventral horns 3 days, 5 days, 1 week, and 2 weeks after transection of the ventral roots close to the spinal cord. The abnormal motoneurons were typically scattered among normal (i.e., nonstained) cells. Even in animals showing the most severe reaction, the whole motoneuron population at the site of rhizotomy was not affected, stained and nonstained perikarya often coexisting side by side. Stained motoneurons were no longer observed 3 weeks after ventral root transection. Changes in neuronal immunoreactivity were also observed after dorsal root transection. However, a different population was affected, i.e., middle‐sized neurons in dorsal horns and at the base of ventral horns. With two monoclonals (A9 and D21), cell bodies remained negative following all operations. It is concluded that axotomy in proximity of the cell body may induce certain neurofilament phosphorylation events in motor neuron perikarya, whereas other phosphorylation events remain confined to the axons under these experimental conditions. The absence of changes after transection of the sciatic nerve in the thigh suggests that neurofilament phosphorylation is a reaction to cell injury rather than a cellular event related to nerve regeneration.
Microscopic and biochemical characterization of lectin binding sites in the cephalopod retina
Authors: Taba Ali , Quezada Beatrice H. , Robles Laura J.
Published: January 2005

Using light and electron microscope cytochemistry and lectin blotting techniques, we have shown that the lectins concanavalin A (Con A), Ricinus communis agglutinin (RCA), and peanut agglutinin (PNA) bind to specific glycoconjugants in the adult cephalopod retina. For light microscope lectin cytochemistry, aldehyde‐fixed, frozen, or Araldite‐embedded, etched sections of cephalopod retinas were incubated with FITC‐ or TRITC‐conjugated lectins and examined by using epifluorescence microscopy. Con A labeled structures in the entire retina including the inner limiting membrane (ILM), rhabdomeric membranes, interphotoreceptor matrix (IPM), and structures in the photoreceptor inner segments. RCA labeling was similar to that of Con A except that there was a decrease in the staining of the rhabdom tips near the ILM. PNA labeled only the interphotoreceptor matrix between apposing rhabdomeres. The intensity of staining of the IPM by PNA also decreased or was absent toward the rhabdom tips. None of the lectins labeled the myeloid bodies located in the photoreceptor inner segments. Electron microscope (EM) lectin cytochemistry was performed on aldehyde‐fixed, LR White–embedded tissue or on Araldite‐embedded, periodate‐etched sections by using gold‐conjugated lectins. EM results confirmed the observations made by light microscopy. Lectin blots with a retinal extract or light‐sensitive membrane fraction revealed a variety of protein bands labeled by all three lectins. Con A and RCA labeled opsin and its aggregates whereas PNA did not. None of the lectins labeled retinochrome.

The labeling of the cephalopod IPM by PNA suggests a structural similarity between the IPM of vertebrates and invertebrates. In other studies, we have demonstrated the presence of a retinoid binding protein in the IPM of cephalopods. Thus, cephalopods may serve as a model for further investigations on the structure and function of the IPM and its role in the vitamin A cycle of the retina.
On the asymmetry of the primary branching of vagal sensory axons: Possible role of the supporting tissue
Authors: Serra Mariana , Alvarez Jaime
Published: January 2005

Central and peripheral nonmedullated processes of vagal nodosal neurons of the cat were studied in normal nerves and after regeneration along their anatomical course and along the hypoglossal nerve. Nonmedullated fibers above the ganglion and in the root had comparable sizes (approximately 0.37 μm2) and caliber distribution. Below the ganglion, the cross‐sectional area increased to 1.0 μm2. In axons of equal caliber, supranodosal and radicular fibers had similar microtubular densities while infranodosal fibers had two‐ to threefold that of the former. Regenerated fibers were studied after a recovery period of 6–9 months. Regrown axons were smaller than their parent axons; in turn, these were smaller than normal axons. This holds for central and peripheral nodosal branches, for homologous and heterologous regeneration. Regrown peripheral branches, either along their anatomical pathway or along the hypoglossal nerve, showed no change in microtubular density. Central branches exhibited their characteristic microtubular content when they regenerated along their anatomical course, but when regrowth took place along the hypoglossal nerve, the original low microtubular content of these branches increased to match the high content of peripheral fibers; parent central axons also shifted their microtubular content toward the pattern of peripheral fibers. We propose that the supporting tissue participates in specifying the organization of axonal microtubules.
Axonal pathfinding during the regeneration of the goldfish optic pathway
Authors: Bernhardt Robert
Published: January 2005

Retinal ganglion cells in fish and amphibians regenerate their axons after transection of the optic nerve. Fiber tracing studies during the third month of regeneration show that the axons have reestablished a basically normal fiber order in the two brachia of the optic tract; axons originating in the ventral hemiretina are concentrated in the dorsal brachium, axons from the dorsal hemiretina in the ventral brachium. Attardi and Sperry (Exp. Neurol. 7:46–64, 1963) first suggested that the reestablishment of the fiber order reflects path‐finding by the regenerating axons. Recently, however, Becker and Cook (Development 101:323–337, 1987) have claimed that the fiber order observed at later stages of regeneration is due to secondary axonal rearrangements and that the initial brachial choice is random.

In order to evaluate whether regenerating axons are capable of navigating in the optic tract and brachia and on the tectum, the present study examined the pathway choices and the morphology of regenerating axons en route to their tectal targets in goldfish. Subsets of axons were labeled at various time intervals (2 to 30 days) following an optic nerve crush, by intraretinal application of the lipophilic fluorescent tracer 1,1‐dioctadecyl‐3‐3‐3′‐3′‐tetra‐methylcarbocyanine (DiI). After a survival time of 18 to 72 hours (to allow for diffusion of DiI along the axons), the experimental animals were perfused with fixative and their right and left optic pathways (nerve, tract, and tectum) were dissected free and separated at the chiasm. Fluorescently labeled axons were traced in whole‐mounted pathways. Pathway choices were examined at the brachial bifurcation where axons from ventral and dorsal hemiretinae normally segregate.

DiI was found to label axons reliably up to their growth cones, even at the earliest stages of regrowth. The pathway choices of the axons were nonrandom. The majority of the ventral axons reached the appropriate, dorsal hemitectum through the appropriate dorsal brachium of the tract. Dorsal axons reached the ventral hemitectum mainly through the ventral brachium. This suggests the presence of specific guidance cues, accessible to the regenerating axons. Differences in the complexity of the growth cones of the regenerating axons (simple in the nerve and tectal fiber layer, complex in the tract and the synaptic layer of the tectum) provide further evidence for specific interactions between the regenerating axons and their substrates along the pathway. These result argue that regenerating retinal axons in fish are capable of axonal path‐finding.
Compartmental and topographical distributions of axons in nerves to the amphibian (Bufo marinus) glutaeus muscle
Authors: Brown David R. , Everett Alan W. , Bennett Max R.
Published: January 2005

The present work seeks to determine if axons to an amphibian muscle are segregated in nerve trunks between the spinal cord and muscle according to their primary nerve destination or their topographical projection in the muscle. The distribution of axons to different compartments and subcompartments of the amphibian (Bufo marinus) glutaeus muscle has been determined in transverse sections of spinal and limb nerves after retrogradely labelling the axons with horseradish peroxidase. Glutaeus axons were dispersed widely through spinal nerves 8 and 9 but loosely gathered together in one quadrant of the sciatic nerve after passing through the lumbar plexus. Glutaeus axons became tightly clustered to the exclusion of other axons along the length of the triceps femoris nerve after it divides from the sciatic nerve. Furthermore, axons destined for one of the two glutaeus primary nerve branches segregate from those of the other branch at the level of the triceps femoris nerve before the glutaeus nerve forms. On the other hand, motoneurones that subserve a primary branch are not segregated, but are found throughout the rostrocaudal extent of the glutaeus motoneurone pool.

Injection of horseradish peroxidase under the epimysium of either the ventral or the dorsal surfaces of the glutaeus muscle labelled motoneurones preferentially in either the rostral or caudal part of the motoneurone pool, respectively. This confirms studies that have shown a topographical projection from the spinal motoneurone pool onto the glutaeus muscle. However, there was no segregation of dorsally projecting axons in the glutaeus and primary nerve branches. Thus, glutaeus axons segregate according to their muscle compartmental projections well before entering the muscle, but they show no organization in nerves with respect to their topographical projections within a compartment.
Morphology of Golgi‐impregnated neurons in hyperstriatum ventralis, pars caudalis in adult male and female canaries
Authors: Nixdorf Barbara E. , Davis Stephen S. , DeVoogd Timothy J.
Published: January 2005

Golgi‐impregnated neurons in the song control nucleus hyperstriatum ventralis, pars caudalis (HVc) in male and female canaries (Serinus canarius) have been divided into classes, primarily on the basis of interneuronal variability in spine density and dendritic branching pattern. At least four neuronal classes are found in HVc: aspinous neurons and three classes of spiny neurons. The “furry” dendrite (FD) cell class consists of neurons with long dendrites that are densely packed with spines. Their cell bodies are between 10 and 15 μm in diameter. Neurons of the thick dendrite (TD) cell class also have long dendrites but only about half as many spines along their dendritic branches. Their cell bodies are between 12 and 18 μm in diameter. Neurons of the short dendrite (SD) cell class are characterized by a low spine density, very thin dendrites, and a small dendritic field. Their cell bodies are between 9 and 13 μm in diameter. The TD class can be divided into two subclasses on the basis of the shape of the dendritic field. Principal component factor analysis and cluster analysis provide objective support for this classification scheme.

Neurons of subclass TD2 are sexually dimorphic. Neurons from males have dendritic trees that are about 70% larger and have 40% more dendritic endings than do neurons from females. There may also be small sex differences in dendritic morphology in the SD class and in the remainder of the TD class. There are clearly no sex differences in the dendritic morphology of neurons from the FD class. The direct pathway which is believed responsible for dimorphic song production in canaries is from HVc to nucleus robustus archistriatalis (RA) and then to the motor neurons which control the avian vocal organ. It is surprising that the most striking dimorphism in the present data occurs in neurons which, on morphological grounds, are unlikely to project to RA.
Lobule structure and somatotopic organization of the medullary facial lobe in the channel catfish Ictalurus punctatus
Authors: Hayama Tomio , Caprio John
Published: January 2005

Correlation of the somatotopic organization of the facial lobe (FL), a primary medullary gustatory nucleus in the channel catfish Ictalurus punctatus, with its lobular substructure was investigated to examine a possible structural basis for the excellent ability of ictalurid catfishes to localize a food source in the environment. The FL in the channel catfish is composed of six longitudinal columns (ie., lobules) extending rostrocaudally and differing from each other in their length and location within the lobe. Each lobule receives segregated input from discrete portions of the external body surface. The three more medial lobules in the FL receive input (from medial to lateral) from the medial mandibular barbel, the lateral mandibular barbel, and the maxillary barbel, respectively. The proximal‐distal axis of each of the barbels is represented in a posteroanterior lobule axis. The largest lobule, the face‐flank lobule, is located dorsolaterally in the FL, whereas the anteroposterior body axis is represented in the posteroanterior lobule axis. This indicates that the neural representation of the external body surface of the channel catfish faces caudally in the FL. The two shortest lobules, positioned ventral to the face‐flank lobule, receive input from the nasal barbel and the pectoral fin, respectively. The rostrocaudal dimensions of each of the barbel lobules correlate well with the relative lengths of the barbels. Taste‐sensitive portions within the three barbel lobules examined were generally confined to the dorsal regions, whereas tactile responses were observed throughout the lobules. The present findings indicate that the FL of the channel catfish is highly organized to localize tactile and taste stimulation of the external body surface and further suggest that the barbel lobules of the FL are differentiated into two portions: a dorsal taste and tactile region, and a ventral, primarily tactile, zone.
Starburst amacrine cells of the primate retina
Authors: Rodieck R. W.
Published: January 2005

A group of readily recognized amacrine cells were observed in Golgi‐impregnated and flat‐mounted macaque, baboon, and human retinas. These cells had roughly circular or oval dendritic fields that were narrowly stratified within the inner plexiform layer (IPL). Most of these cells stratified in the inner half (sublamina b) of the IPL, and they had their somata in the ganglion‐cell layer; a few stratified in the outer half (sublamina a) of the IPL and had their somata in the amacrine‐cell layer.

Typically, a single dendrite issued from the soma, and, after passing for 10 μm or so, gave rise to five or more radiate processes. As these processes neared the edge of the dendritic field they branched, turned, and became varicose. Most showed no evidence of an axon, although a few had a short process extending inward, toward the optic‐fiber layer. Dendritic‐field diameters were about 100 μm near the fovea and increased to about 350 μm in the peripheral retina. Mean somal diameter also increased slightly from near the fovea (7.8 μm) to the periphery (8.7 μm).

Although the primate cells are smaller, and there are some minor differences in the form of the dendritic fields, these cells appear to be morphologically equivalent to the starburst amacrines of the rabbit retina, whose counterparts have also been observed in the retinas of rats and cats.

Presuming that these cells correspond to the choline acetyltransferase immunoreactive primate cells described by Mariani and Hersh (J. Comp. Neurol. 267:269–280, '87), their overlap factor is about ten for the type whose somata lay in the ganglion‐cell layer and about 0.25 for those whose somata lay in the amacrine‐cell layer.
Terminal arbors of individual “Feedback” axons projecting from area V2 to V1 in the macaque monkey: A study using immunohistochemistry of anterogradely transported Phaseolus vulgaris‐leucoagglutinin
Authors: Rockland Kathleen S. , Virga Agnes
Published: January 2005

In the present study, the anterograde tracer Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was injected into area V2 in order to demonstrate the precise morphology of individual axons from area V2 to V1. On the basis of 28 complete axon reconstructions, several characteristic features have been identified. (1) Individual axons arborize in multiple layers: 1, 2, 5, and (inconstantly) 3. A single axon may have numerous terminal clusters in layers 1 and 2, but at most one in layer 3. (2) Axons typically ascend to layer 1, turn asymmetrically in one direction, and travel for long distances in this layer (1.10–4.30 mm; dimensions uncorrected for shrinkage). A few axons (three of 28 reconstructed) were found to have a single terminal cluster (0.3–0.5 mm wide) in layers 1 and 2. (3) Collaterals in layer 5 seem to extend over shorter distances (0.60 mm or less). (4) Delicate sprays of boutons (both beads and spines) are clustered along the main trunk. Spacing is variable but usually ranges from 0.35 mm to 0.65 mm. (5) In addition to clustered boutons, there can be linear collaterals, continuously studded with boutons, parallel to the main axon in layer 1.

These results indicate that axons from V2 have complex radial and tangential distributions in V1. Terminations in different layers may be directed to different sets of neurons or to different portions of the dendritic tree (for example, distal portions of pyramidal neuron apical dendrites in layers 1 and 2, but more proximal portions in layer 3). Clustered terminations over wide tangential areas may imply a divergent innervation by a single axon of multiple compartmental structures, such as ocular dominance columns or cytochrome oxidase patches.
Selective destruction of mossy fibers and granule cells with preservation of the GABAergic network in the inferior region of the rat hippocampus after colchicine treatment
Authors: Robain O. , Represa A. , Jardin L. , Ben‐Ari Y.
Published: January 2005

Lesions induced by colchicine injection into the rat hippocampus were investigated by means of electron microscopy and GABA immunocytochemistry. Granule cells were nearly completely destroyed 3 days after colchicine injection; since the necrosis of their axonal endings was delayed, an anterograde degeneration of the mossy fibers had probably taken place. The selectivity of the lesions was not limited to granule cells, for some pyramidal neurons in CA1 pyramidal layer were damaged. It was, however, striking to observe that throughout the hippocampal structure GABAergic neurons were spared from the effects of colchicine. For instance, GABAergic neurons were found in the vicinity of the completely destroyed granule cell layer. GABAergic neurons and terminals were also present in the CA3 region where the GABA‐containing terminals formed a dense network of synapses with somata and dendrites of pyramidal cells. It was interesting to note that, consistent with previous studies, the GABAergic neurons in CA3 are innervated by mossy fibers.

We conclude that after colchicine treatment the destruction of the granule cells was not associated with a lesion of the GABAergic network. This selective lesion provides a useful model with which to study the properties of CA3 neurons deprived of their major excitatory input but with an intact inhibitory network.
Efferent connections of the dorsal cortex of the lizard Gekko gecko studied with Phaseolus vulgaris‐leucoagglutinin
Authors: Hoogland Piet V. , Vermeulen‐Vanderzee Eefke
Published: January 2005

The efferent connections from the dorsal cortex of the lizard Gekko gecko have been studied with the anterograde tracer Phaseolus vulgaris‐leucoagglutinin. It appeared that the dorsal cortex is not a homogeneous structure as far as the efferent connections are concerned. All parts of the dorsal cortex project to the septum. All parts except the most medial project to the dorsal ventricular ridge, amygdala, nucleus periventricularis hypothalami, area lateralis hypothalami, and the anterior olfactory nucleus. The most medial part, in addition to the septal projections, is connected with the medial cortex and the contralateral medial and dorsal cortices. From the rostral part additional projections could be traced to the nucleus dorsolateralis hypothalami, nucleus ventromedialis thalami, nucleus dorsolateralis thalami, striatum, pallial thickening, medial cortex, nucleus olfactorius anterior, and the main and accessory olfactory bulbs.

From the caudal part additional projections exist to the nucleus dorsomedialis thalami, nucleus accumbens, and the contralateral dorsal cortex. A system of intrinsic connections exists that can be subdivided into four subsystems, each of which subserves the interconnections within four subdivisions of the cortex: (1) the superficial medial part, (2) the deep medial part, (3) the caudal lateral and caudal intermediate parts, and (4) the rostral lateral and rostral intermediate parts. Connections between these four areas are scarce.

From the present results the conclusion is drawn that the dorsal cortex of the lizard Gekko gecko has many hodological aspects in common with the ventral subiculum of mammals. The present results do not support the hypothesis that the dorsal cortex is the reptilian equivalent of the mammalian neocortex.
Spatial organization of thalamocortical and corticothalamic projection systems in the rat SmI barrel cortex
Authors: Chmielowska Jolanta , Carvell George E. , Simons Daniel J.
Published: January 2005

Axonal tracing techniques were used to examine the distribution of corticothalamic projection neurons in relation to the organization of the thalamocortical recipient zones in the whisker representation of the rat first somatic sensory cortex. Following injection of horseradish peroxidase into the physiologically defined vibrissa area in the ventrobasal complex of the thalamus, labeling in the cortex had a columnar appearance. Dense patches of anterograde labeling were located within the centers of the layer IV barrels and extended superficially through lamina III; the septa between barrels contained considerably less reaction product. Retrogradely labeled neurons were observed in lower layer V and layer VI where they were concentrated preferentially deep to the barrel centers. Regions deep to the septa displayed less over‐all labeling and a lower relative number of thalamic projecting neurons. Zones having the larger numbers of retrogradely labeled cells also contained terminallike labeling of either corticothalamic or thalamocortical origin. Following an injection that included the posterior group medial to the ventrobasal complex, anterograde labeling in layer IV was located largely in the septa. In conjunction with previous findings concerning the origin and termination of other projection systems in the barrel cortex, these results suggest that a vibrissal column contains a central core zone intimately linked with the ventrobasal thalamus that is bounded by narrower regions of more diverse inputs and outputs that form an interface between adjacent cortical columns.
Chemoanatomical organization of the noradrenergic input from locus coeruleus to the olfactory bulb of the adult rat
Authors: McLean John H. , Shipley Michael T. , Nickell William T. , Aston‐Jones Gary , Reyher Christian K. H.
Published: January 2005

The locus coeruleus contains noradrenergic neurons which project widely throughout the CNS. A major target of locus coeruleus projections in the rat is the olfactory bulb (Shipley et al.: Brain Res. 329:294–299, '85) but the organization of the projections within the bulb has not been systematically examined. In this study, the laminar distribution and densities of locus coeruleus‐noradrenergic fibers in the main and accessory olfactory bulbs were determined with anterograde tracing and immunocytochemical techniques.

Following iontophoretic injections of 1% wheat germ agglutinin‐horseradish peroxidase into the locus coeruleus, the densest anterograde label in the accessory olfactory bulb was observed in the external plexiform layer, granule cell layer, and especially in the internal part of the mitral cell layer. Virtually no label was observed in the glomerular layer. In the main olfactory bulb, labelled axons were observed in the granule cell layer, in the internal and external plexiform layers, occasionally in the mitral cell layer, and least often in the glomerular layer.

Noradrenergic fibers in the olfactory bulb were identified by using immunocytochemistry with an antibody to dopamine‐β‐hydroxylase. Laminar patterns and densities of noradrenergic innervation were determined with quantitative image analysis. In the accessory olfactory bulb, the densest innervation was in the innermost portion of the mitral cell layer followed by the granule cell layer, the superficial part of the mitral cell layer, and the external plexiform layer. The density of fibers in the glomerular layer was least. The laminar pattern of noradrenergic fiber distribution in the main olfactory bulb was similar to that in accessory olfactory bulb.

The present studies demonstrate that locus coeruleus‐noradrenergic fibers terminate preferentially in the internal plexiform, granule cell, and external plexiform layers. This suggests that the major influence of the locus coeruleus input to both the main and accessory the olfactory bulbs is on the predominant neuronal element in those layers, the granule cells. Additional studies are needed to resolve how this input influences specific olfactory bulb circuits.
Retinotopic organization within the lateral posterior complex of the cat
Authors: Hutchins Bob , Updyke B. V.
Published: January 2005

Electrophysiological mapping methods were employed to systematically study the retinotopic organization within the cat's lateral posterior complex (LP). Visual responses were recorded in all the major subdivisions of the LP as well as in several adjoining cell groups. Specifically, separate representations of the visual field were identified for pulvinar, zones LPl‐c, LPl‐r, LPi, and LPm. Partial representations of the visual field were also evident in the geniculate wing, subdivisions of the lateral posterior shell, the inferior division of the posterior nuclear group, the suprageniculate nucleus, and the central lateral nucleus. Sufficient mapping observations were made to define the internal organization of major visual representations. Additionally, there was a very close correspondence between the mapping observations when they were compared with the cytoarchitectural criteria for recognizing functional cell groups (Updyke: J. Comp. Neurol. 219:143–181, '83).
Distribution of noradrenaline immunoreactivity in the forebrain and midbrain of the lizard Gekko gecko
Authors: Smeets Wilhelmus J. A. J. , Steinbusch Harry W. M.
Published: January 2005

The distribution of noradrenaline (NA) immunoreactivity in the forebrain and midbrain of the lizard Gekko gecko was studied by means of recently developed antibodies against NA. Noradrenaline‐containing cell bodies are found in the hypothalamic periventricular organ and ependymal wall of the infundibular recess of the diencephalon. They are also present in the locus coeruleus and the nucleus of the solitary tract of the brainstem. Noradrenaline‐immunoreactive (NAi) fibers and varicosities are widely, but not uniformly, distributed throughout the forebrain and midbrain. In the telencephalon, dense plexuses of NAi fibers are found in the bed nucleus of the medial forebrain bundle, the vertical limb of the nucleus of the diagonal band of Broca, and the caudoventral part of the septal region. The diencephalon, the periventricular preoptic area, the supraoptic nucleus, and, in particular, the medial habenular nucleus are densely innervated by NAi fibers, whereas in the midbrain NAi plexuses are found in the ventral tegmental area, the substantia nigra and its dorsolateral extension (RA8), and in an area ventral to the nucleus interpeduncularis, pars ventralis. Moderately dense plexuses of NAi fibers are found in the small‐celled medial cortex, the dorsal cortex, and the midbrain tectum. The remaining forebrain and midbrain areas are generally not or only sparsely innervated by NAi fibers.

The distribution of NAi cell bodies and fibers resembles the pattern revealed with antibodies against dopamine‐β‐hydroxylase (DBH). A remarkable exception is that the cells in the hypothalamic periventricular organ and ependymal wall of the infundibular recess are immunonegative for DBH. Possible explanations for this discrepancy are discussed. The present study on the distribution of NA immunoreactivity in the brain of Gekko gecko combined with the results of a previous report on the distribution of dopamine in the same species (Smeets et al., '86b) offer the opportunity to differentiate between the two catecholamines in the brain of this vertebrate.
Extrinsic determinants of retinal ganglion cell development in primates
Authors: Leventhal Audie G. , Ault Steven J. , Vitek Damgmar J. , Shou Tiande
Published: January 2005

As in all mammals studied to date, primate retina contains morphologically distinct classes of retinal ganglion cells (Polyak: The Retina. Chicago: University of Chicago Press, '41; Boycott and Dowling: Philos. Trans. R. Soc. Lond. [Biol.] 225:109–184, '69; Leventhal et al.: Science 213:1139–1142, '81; Perry et al.: Neuroscience 12:1101–1123, '84; Rodieck et al.: J. Comp. Neurol. 233:115–132, '85; Rodieck: In H.D. Steklis and J. Erwin (eds): Comparative Primate Biology, Volume 4: Neurosciences. New York: Alan R. Liss, Inc., pp. 203–278, '88). We have now studied the morphologies, central projections, and retinal distributions of the major morphological classes of ganglion cells in the normal adult monkey, the newborn monkey, and the adult monkey in which restricted regions of retina were depleted of ganglion cells at birth as a result of small lesions made around the perimeter of the optic disc. Both old‐world (Macaca fascicularis) and new‐world (Saimiri sciureus) monkeys were studied.

Our results indicate that, at birth, the major morphological classes of monkey retinal ganglion cells are recognizable; cells in central regions are close to adult size whereas cells in peripheral regions are much smaller than in the adult. As in the adult (Stone et al.: J. Comp. Neurol. 150:333–348, '73), in newborn monkeys there is a very sharp division between ipsilaterally and contralaterally projecting retinal ganglion cells (nasotemporal division). Consistent with earlier work (Hendrickson and Kupfer: Invest. Ophthalmol. 15:746–756, '76) we find that the foveal pit in the neonate is immature and contains many more ganglion cells than in the adult.

In the adult monkey in which the density of retinal ganglion cells in the central retina was reduced experimentally at birth, the fovea appeared immature, and an abnormally large number of retinal ganglion cells were distributed throughout the foveal pit. The cell bodies and dendritic fields of ganglion cells that developed within cell‐poor regions of the central retina were nearly ten times larger than normal. In peripheral regions the effects were smaller. The dendrites of the abnormally large foveal cells on the borders of cell‐poor zones were directed normally toward the foveal pit. They did not extend preferentially into the cell‐poor region as do the abnormally large cells on the borders of experimentally induced cell‐poor regions of cat central retina (Leventhal et al.: J. Neurosci. 8:1485–1499, '88) or, as we found here, in paracentral regions of primate retina.

It is hypothesized that (1) competition for afferents as well as direct interactions among neighboring ganglion cells in the immature retina may contribute to the development of the structure of primate retinal ganglion cells, (2) other factors are also likely to be involved, and (3) foveal development can only proceed normally if the central retina contains an extremely high concentration of retinal ganglion cells.
Deprived somatosensory‐motor experience in stumptailed monkey neocortex: Dendritic spine density and dendritic branching of layer IIIB pyramidal cells
Authors: Bryan Guy K. , Riesen Austin H.
Published: January 2005

Infant macaque monkeys (Macaca arctoides) were individually raised to age 6 months in large clear cubes built into one wall of a control colony that allowed them visual access to it but not tactile contact. The two deprivation conditions (Cond 2 and Cond 3) were equal both in physical size and with respect to partial social isolation. They differed in the degree of somatosensory‐motor opportunity available during development in that the Cond 2 chamber was empty, whereas Cond 3 contained ladders, a trapeze, and play objects. Four monkeys from each of these conditions were compared with four colony‐reared (Cond CR) monkeys. Neuroanatomical changes were evaluated by using light microscopy in Golgi‐Cox‐stained neocortex. Dendritic spines on the apical shafts of layer IIIB pyramidal cells were counted in primary motor (MI), somatosensory (SI), and visual (area 17, V1) cortical regions. Layer IIIB pyramidal neurons with somas of medium size were selected from each cortical region and the density of apical dendritic spines determined. The basilar dendritic branches of these same neurons were traced, and the dendritic branching complexity was assessed in order to compare the sensitivity of the dendritic spine and branching measures consequent to deprived rearing. The number of apical dendritic spines was significantly reduced in Cond 2 when compared with either Cond 3 or Cond CR (which did not differ from each other). This occurred in both MI and SI cortex, but not in the visual cortex, the region used as a control for a global brain effect. Branching complexity measured on the same pyramidal neurons was reduced only in MI cortex of Cond 2. These results show spine density, a more direct measure of neuronal connectivity, to be the more sensitive measure of early environmental deprivation. Also, the enriched environment provided by Cond 3 relative to Cond 2 offset the effect of partial social isolation such that both morphometric measures had values comparable to Cond CR monkeys.
Morphological substrate for eyelid movements: Innervation and structure of primate levator palpebrae superioris and orbicularis oculi muscles
Authors: Porter John D. , Burns Leigh Ann , May Paul J.
Published: January 2005

The levator palpebrae superioris and orbicularis oculi are antagonistic muscles that function during movements of the eyelid. The levator also functions in conjunction with superior and inferior rectus muscles in coordinated eye/lid movements. The present study examined the innervation and morphology of these muscles in Cynomolgous monkeys (Macaca fascicularis) in order to provide a better understanding of the anatomical substrate for lid movements. Motoneurons innervating the levator and orbicularis muscles were identified and localized by retrograde transport of WGA/HRP and HRP. Retrogradely labelled levator motoneurons were distributed bilaterally throughout the caudal central division of the oculomotor nucleus. A few labelled cells were also present within the contralateral superior rectus division, possibly because of the spread of tracer at the injection site. The possibility that individual motoneurons collateralize to innervate the levator muscle bilaterally was tested by using double retrograde labelling techniques. Doubly labelled levator motoneurons could not be detected by suing a combination of tracers (HRP and Fast Blue). Motoneurons innervating the upper lid portion of the orbicularis oculi muscle were distributed within the dorsal subdivision of the ipsilateral facial motor nucleus, with a few neurons in the corresponding locus of the contralateral facial nucleus. Species differences in levator motoneuron distribution, particularly distinctions in lateral‐eyed versus frontal‐eyed mammals, are discussed in relation to the neural control of lid movements.

The levator palpebrae superioris contains three of the same ultrastructurally defined types of singly innervated muscle fiber found in the global layer of other extraocular muscles and an additional, unique slow‐twitch fiber type. Moreover, the multiply innervated fiber types so characteristic of the other extraocular muscles are conspicuously absent from levator muscles. Unlike the rectus and oblique extraocular muscles, the levator lacks a layered distribution of fiber types. The morphological profiles of levator muscle fiber types are such that they generally do not respect traditional fiber classification schemes, but are consistent with a role for the levator in sustained elevation of the lid.

The orbicularis oculi muscle, by contrast, exhibited three distinct fiber types that resembled categories of skeletal muscle twitch fibers. One slow‐twitch and two fast‐twitch fiber types were noted. On the basis of oxidative enzyme profiles and mitochrondrial content, the majority of orbicularis oculi fibers would be fatigue‐prone, an assessment consistent with their rapid onset/offset of action in blinks. Morphological differences between the levator palpebrae superioris and orbicularis oculi muscles reflect not only their dis‐tinct functional roles in blinking and other lid movements, but also their diverse embryological origins.