Distribution of pre-pro-glucagon and glucagon-like peptide-1 receptor messenger RNAs in the rat central nervous system

Glucagon-like peptide-1 (GLP-1) is derived from the peptide precursor pre-pro-glucagon (PPG) by enzymatic cleavage and acts via its receptor, glucagon-like peptide-1 receptor (GLP-1R). By using riboprobes complementary to PPG and GLP-1R, we described the distribution of PPG and GLP-1R messenger RNAs (mRNAs) in the central nervous system of the rat. PPG mRNA-expressing perikarya were restricted to the nucleus of the solitary tact or to the dorsal and ventral medulla and olfactory bulb. GLP-1R mRNA was detected in numerous brain regions, including the mitral cell layer of the olfactory bulb; temporal cortex; caudal hippocampus; lateral septum; amygdala; nucleus accumbens; ventral pallium; nucleus basalis Meynert; bed nucleus of the stria terminalis; preoptic area; paraventricular, supraoptic, arcuate, and dorsomedial nuclei of the hypothalamus; lateral habenula; zona incerta; substantia innominata; posterior thalamic nuclei; ventral tegmental area; dorsal tegmental, posterodorsal tegmental, and interpeduncular nuclei; substantia nigra, central gray; raphe nuclei; parabrachial nuclei; locus ceruleus, nucleus of the solitary tract; area postrema; dorsal nucleus of the vagus; lateral reticular nucleus; and spinal cord. These studies, in addition to describing the sites of GLP-1 and GLP-1R synthesis, suggest that the efferent connections from the nucleus of the solitary tract are more widespread than previously reported. Although the current role of GLP-1 in regulating neuronal physiology is not known, these studies provide detailed information about the sites of GLP-1 synthesis and potential sites of action, an important first step in evaluating the function of GLP-1 in the brain. The widespread distribution of GLP-1R mRNA-containing cells strongly suggests that GLP-1 not only functions as a satiety factor but also acts as a neurotransmitter or neuromodulator in anatomically and functionally distinct areas of the central nervous system.     

Projections from the lateral, basal, and accessory basal nuclei of the amygdala to the hippocampal formation in rat

The amygdaloid complex and hippocampal formation mediate functions involving emotion and memory. To investigate the connections that regulate the interactions between these regions, we injected the anterograde tracer Phaseolus vulgaris-leucoagglutinin into various divisions of the lateral, basal, and accessory basal nuclei of the rat amygdala. The heaviest projection to the entorhinal cortex originates in the medial division of the lateral nucleus which innervates layer III of the ventral intermediate and dorsal intermediate subfields. In the basal nucleus, the heaviest projection arises in the parvicellular division and terminates in layer III of the amygdalo-entorhinal transitional subfield. In the accessory basal nucleus, the parvicellular division heavily innervates layer V of the ventral intermediate subfield. The most substantial projection to the hippocampus originates in the basal nucleus. The caudomedial portion of the parvicellular division projects heavily to the stratum oriens and stratum radiatum of CA3 and CA1. The accessory basal nucleus projects to the stratum lacunosum-moleculare of CA1. The subiculum receives a substantial input from the caudomedial parvicellular division. The parasubiculum receives dense projections from the caudal portion of the medial division of the lateral nucleus, the caudomedial parvicellular division of the basal nucleus, and the parvicellular division of the accessory basal nucleus. Our data show that select nuclear divisions of the amygdala project to the entorhinal cortex, hippocampus, subiculum, and parasubiculum in segregated rather than overlapping terminal fields. These data suggest that the amygdaloid complex is in a position to modulate different stages of information processing within the hippocampal formation.     

NADPH-diaphorase-positive neurons and pathways in the brain of the frog Rana esculenta

We described the NADPH-diaphorase-containing neurons and fibres in the brain of the frog Rana esculenta. In the telencephalon stained cells occurred in the olfactory bulb, all subdivisions of the pallium, the diagonal band, the medial septum and the striatum. The olfactory glomeruli showed the most intense enzyme reaction. The neuropil of the accessory olfactory bulb was also heavily stained and this staining extended to the rostral diencephalon through the ventral lateral pallium. Fibre staining was less intense in the medial pallium and the medial septum. In the diencephalon, NADPH-diaphorase staining was concentrated in the middle third of this part of the brain. The stained cells were embedded in a dense network of thin, stained fibres and terminals in the lateral anterior and central thalamic nuclei. Faintly stained cells were present also in the posterior preoptic nucleus, anterior thalamic nucleus, nucleus of Bellonci, corpus geniculatum thalamicum and the suprachismatic nucleus. In the mesencephalon, heavily stained cells occurred in the nucleus profundus mesencephali, anterodorsal, anteroventral and especially in the posterodorsal tegmental nuclei. Neuronal staining was less intense in the optic tectum and the torus semicircularis. Thick, intensely stained fibres occupied the lateral part of the tegmentum and the 7th layer of the tectum. A loose network of thin fibres occupied the periventricular area and all tegmental nuclei. In the rhombencephalon, the reticular nuclei and the inferior raphe nucleus showed the most intense staining, while some cells in the nucleus of the solitary tract and the dorsal column nuclei were less intensely stained. Heavy staining of fibres was characteristic of the spinal trigeminal tract, the solitary tract and the reticulospinal pathway.     

Antibiotic and prednisolone therapy of erysipelas: a randomized, double blind, placebo-controlled study

In the early eighties we found sex differences in the vomeronasal organ (VNO) and hypothesized that the vomeronasal system (VNS), a complex neural network involved in the control of reproductive behavior, might be sexually dimorphic. At that time sex differences had already been described for some structures that receive VNO input, such as the medial amygdala, the medial preoptic area, the ventromedial hypothalamic nucleus, and the ventral region of the premammillary nucleus. Since then, we have shown sex differences in the accessory olfactory bulb (AOB), the bed nucleus of the accessory olfactory tract (BAOT), and the bed nucleus of the stria terminalis (BST). When new VNS connections were found, all of them ended in nuclei that present sex differences. In general, sex differences in the olfactory system show two morphological patterns: one in which males present greater morphological measures than females, and just the opposite. To explain the morphometric measures of males in the latter, it has been hypothesized that androgens serve as inhibitors. Our work on the involvement of the GABA(A) receptor in the development of AOB and maternal behavior sex differences also suggests that neonatal changes in neuronal membrane permeability to the ion Cl- differences. This might be the first animal model to help us to understand the situation in which human genetic and gonadal sex do not agree with brain and behavioral sex. Finally, we stress that sex differences in the VNS constitute a neurofunctional model for understanding sex differences in reproductive behaviors.     

Basal ganglia organization in amphibians: afferent connections to the striatum and the nucleus accumbens

As part of a research program to determine if the organization of basal ganglia (BG) of amphibians is homologous to that of amniotes, the afferent connections of the BG in the anurans Xenopus laevis and Rana perezi and the urodele Pleurodeles waltl were investigated with sensitive tract-tracing techniques. Hodological evidence is presented that supports a division of the amphibian BG into a nucleus accumbens and a striatum. Both structures have inputs in common from the olfactory bulb, medial pallium, striatopallial transition area, preoptic area, ventral thalamus, ventral hypothalamic nucleus, posterior tubercle, several mesencephalic and rhombencephalic reticular nuclei, locus coeruleus, raphe, and the nucleus of the solitary tract. Several nuclei that project to both subdivisions of the BG, however, show a clear preference for either the striatum (lateral amygdala, parabrachial nucleus) or the nucleus accumbens (medial amygdala, ventral midbrain tegmentum). In addition, the anterior entopeduncular nucleus, central thalamic nucleus, anterior and posteroventral divisions of the lateral thalamic nucleus, and torus semicircularis project exclusively to the striatum, whereas the anterior thalamic nucleus, anteroventral, and anterodorsal tegmental nuclei provide inputs solely to the nucleus accumbens. Apart from this subdivision of the basal forebrain, the results of the present study have revealed more elaborate patterns of afferent projections to the BG of amphibians than previously thought. Moreover, regional differences within the striatum and the nucleus accumbens were demonstrated, suggesting the existence of functional subdivisions. The present study has revealed that the organization of the afferent connections to the BG in amphibians is basically similar to that of amniotes. According to their afferent connections, the striatum and the nucleus accumbens of amphibians may play a key role in processing olfactory, visual, auditory, lateral line, and visceral information. However, contrary to the situation in amniotes, only a minor involvement of pallial structures on the BG functions is present in amphibians.     

Afferent and efferent connections of the diencephalic prepacemaker nucleus in the weakly electric fish, Eigenmannia virescens: interactions between the electromotor system and the neuroendocrine axis

The organization of the ventral nucleus of the ventral telencephalon (Vv) was examined in the weakly electric fish, Eigenmannia virescens. This nucleus, which is considered the teleost homologue to the basal forebrain nuclei of other vertebrates, was subdivided into dorsal and ventral subdivisions, based upon cytoarchitectonic, immunohistochemical, and connectional criteria. Afferent projections were observed from the medial olfactory bulb as well as the terminal nerve ganglion. Telencephalic afferents to the Vv were very restricted, consisting of the supracommissural and the dorsal intermediate nuclei of the ventral telencephalon, the nucleus taenia, and the medial region of the posterior nucleus of the dorsal telencephalon. However, the major afferents to the Vv were diencephalic, particularly those originating from the rostral preoptic area and other hypothalamic nuclei. Additional afferents included the posterior tubercular nucleus, the locus coeruleus, the medial perilemniscal nucleus, and the periventricular nucleus of the posterior tuberculum. Relatively weak projections were observed from the ventral thalamus and the dorsal posterior thalamic nucleus. As described previously, the diencephalic complex of the central posterior thalamic nucleus/prepacemaker nucleus (CP/PPn), which also has cells that innervate the pacemaker circuitry controlling the production of an electric organ discharge, projects to the Vv. Terminal fields of the Vv were observed to be coextensive with afferent cell groups in the preoptic area, lateral and caudal hypothalamic nuclei, and thalamus. An additional efferent target of the Vv was the pretectal nucleus electrosensorius. That many cell groups that are connected with the Vv are also connected with the CP/PPn, particularly the preoptic and hypothalamic nuclei, suggests that the electrocommunicatory system is intimately linked with basal forebrain limbic pathways.     

Organization of projections from the basomedial nucleus of the amygdala: a PHAL study in the rat

The organization of axonal projections from the basomedial nucleus of the amygdala (BMA) was examined with the Phaseolus vulgaris leucoagglutinin (PHAL) method in adult male rats. The anterior and posterior parts of the BMA, recognized on cytoarchitectonic grounds, display very different projection patterns. Within the amygdala, the anterior basomedial nucleus (BMAa) heavily innervates the central, medial, and anterior cortical nuclei. In contrast, the posterior basomedial nucleus (BMAp) sends a dense projection to the lateral nucleus, and to restricted parts of the central and medial nuclei. Extra-amygdalar projections from the BMA are divided into ascending and descending components. The former end in the cerebral cortex, striatum, and septum. The BMAa mainly innervates olfactory (piriform, transitional) and insular areas, whereas the BMAp also innervates inferior temporal (perirhinal, ectorhinal) and medial prefrontal (infralimbic, prelimbic) areas and the hippocampal formation. Within the striatum, the BMAa densely innervates the striatal fundus, whereas the nucleus accumbens receives a heavy input from the BMAp. Both parts of the BMA send massive projections to distinct regions of the bed nuclei of the stria terminalis. Descending projections from the BMA end primarily in the hypothalamus. The BMAa sends a major input to the lateral hypothalamic area, whereas the BMAp innervates the ventromedial nucleus particularly heavily. Injections were also placed in the anterior cortical nucleus (COAa), a cell group superficially adjacent to the BMAa. PHAL-labeled axons from this cell group mainly ascend into the amygdala and olfactory areas, and descend into the thalamus and lateral hypothalamic area. Based on connections, the COAa and BMAa are part of the same functional system. The results suggest that cytoarchitectonically distinct anterior and posterior parts of the BMA are also hodologically distinct and form parts of distinct anatomical circuits probably involved in mediating different behaviors (for example, feeding and social behaviors vs. emotion-related learning, respectively).     

Olfactory and nonolfactory projections in the river lamprey (Lampetra fluviatilis) telencephalon

The projections of the olfactory bulb, the primordial dorsal, piriform and hippocampal pallia, and of the dorsal thalamus were studied in the lamprey Lampetra fluviatilis using horseradish peroxidase (HRP) and HRP coupled to the wheat germ agglutinin (WGA-HRP). There was obtained an experimental morphological evidence of the presence of the direct thalamo-telencephalic projections in this vertebrate species. The anterior and posterior parts of the dorsal thalamic nucleus, the nucleus of Bellonci, the primordial geniculate bodies, the rostral part of the midbrain were identified as the sources of the telencephalic afferents. These connections may serve as a morphological substrate for transmission of nonolfactory impulses to the telencephalon of the lamprey. The projections of the nucleus of Bellonci into the primordial hippocamp were compared to the limbic thalamo-hippocampal pathways of other vertebrates. We have established, that the fibers ascending from the dorsal thalamus were distributed in the same areas, as those descending from the olfactory bulb. These are: mainly the primordial hippocamp and only a few fibers reach the dorsal and piriform pallia, as well as an area free of olfactory projections--the dorsal part of the subhippocampal lobe. We have also demonstrated that, the secondary olfactory fibers mainly projected ipsilaterally to the primordial dorsal and piriform pallia. A lesser dense bulbar projection has been observed ipsilaterally in the primordial hippocamp and in the ventral part of the subhippocampal lobe. Only few olfactory projections were found in the pallial areas and in the subhippocampal lobe contralaterally. The olfactory fiber terminals were also observed ipsilaterally in the septum, striatum, preoptic area and in the contralateral olfactory bulb. Bilateral bulbofugal projections also occur in the diencephalon, namely in the ventral thalamus and in the hypothalamus. Caudally, the secondary olfactory fibers can be traced up to the area of the posterior tuberculum. Afferents to the olfactory bulb in the river lamprey originate in the subhippocampal lobe, in all three pallial formations and probably in the dorsal thalamus. These structures are at the same time the target zones for the olfactory bulb efferent projections, thus being connected reciprocally with the olfactory bulb.     

Quality of center day care and attunement between parents and caregivers: center day care in cross-national perspective

The efferent projections from the periaqueductal gray matter (PAG) to the parabrachial nucleus (PB) were studied in the rat following microinjections of the anterograde axonal tracer Phaseolus vulgaris-leucoagglutinin (PHA-L) into restricted regions of the PAG. The dorsomedial and dorsolateral PAG columns project almost exclusively to the superior lateral PB subnucleus, whereas the lateral and ventrolateral PAG columns project to five lateral PB sites: dorsal lateral subnucleus, medial and lateral crescent areas (which flank the dorsal lateral PB subnucleus), central lateral subnucleus (rostral portion), and superior lateral subnucleus. The PAG region lying near the cerebral aqueduct projects to five lateral PB sites: external lateral subnucleus (inner subdivision), medial and lateral crescent areas, central lateral subnucleus (rostral portion), and dorsal lateral subnucleus. The internal lateral PB subnucleus, which projects exclusively to the intralaminar thalamic nuclei, and the K?lliker-Fuse nucleus were not innervated by the PAG. The PAG selectively innervates individual PB subnuclei that may be part of the spino-parachio-forebrain pathway. All PAG columns, including the aqueductal region, project to the superior lateral PB subnucleus, a presumed nociceptive relay site that receives inputs from multiple spinal cord regions (laminae I, V, and VIII) and projects to the ventromedial and retrochiasmatic hypothalamic areas-two regions that have been implicated in complex goal-directed behavior (e.g., food intake and reproductive function). Earlier studies demonstrated that the dorsal lateral and external lateral PB subnuclei (inner division) receive overlapping inputs from the superficial dorsal horn (laminae I and II) and the nucleus tractus solitarius, and both PB subnuclei send projections to limbic forebrain areas (e.g., hypothalamus, preoptic region, amygdala). Because the PAG projects to both of these PB subnuclei, this projection system possibly functions as a behavioral state-dependent filter system that modulates ascending nociceptive and/or visceral information as it is relayed through the PB to forebrain sites.     

Localization of the neuromedin K receptor (NK3) in the central nervous system of the rat

The distribution of the neuromedin K receptor (NK3; NKR) in the central nervous system was investigated in the adult rat by using in situ hybridization and immunohistochemical techniques. The rabbit anti-NKR antibody was raised against a bacterial fusion protein containing a C-terminal portion of NKR and affinity purified with a Sepharose 4B column conjugated to the fusion protein. Immunoblot analysis was performed to test the reactivity and specificity of the antibody. Crude membrane was prepared from cDNA-transfected Chinese hamster ovary (CHO) cells expressing each of the rat NKR, substance P receptor (NK1; SPR), and substance K receptor (NK2; SKR) and from the hypothalamus, cerebral cortex, and cerebellum. Immunoreactive bands were observed specifically in the NKR-CHO cells, hypothalamus, and cerebral cortex but not in the SPR- or SKR-CHO cells, nor in the cerebellum. Molecular weights of the immunoreactive bands ranged from 73 to 89 kDa and from 59 to 83 kDa in the NKR-CHO cells and tissues, respectively. The distribution of NKR-like immunoreactivity coincided with that of NKR mRNA. The expression of NKR was indicated on neuronal cell bodies and dendrites. NKR was found to be expressed intensely or moderately in neurons in the glomerular and granule cell layers of the main olfactory bulb; glomerular and mitral cell layers of the accessory olfactory bulb; layers IV and V of the cerebral neocortex; medial septal nucleus; nucleus of the diagonal band; bed nucleus of the stria terminalis; globus pallidus; ventral pallidum; paraventricular nucleus; supraoptic nucleus; zona incerta; dorsal, lateral, and posterior hypothalamic areas; amygdaloid nuclei; medial habenular nucleus; ventral tegmental area; midbrain periaqueductal gray; interpeduncular nuclei; substantia nigra pars compacta; linear, median, dorsal, and pontine raphe nuclei; posteromedial tegmental nucleus; sphenoid nucleus; nucleus of the solitary tract; intermediate and rostroventrolateral reticular nuclei; and lamina II of the caudal spinal trigeminal nucleus and spinal dorsal horn. These findings are discussed in relation to the physiological functions associated with neuromedin K.     

Immunocytochemical localization and description of neurons expressing serotonin2 receptors in the rat brain

Serotonin2 receptors have been implicated in a variety of behavioral and physiological processes, as well as a number of neuropsychiatric disorders. To specify the brain regions and specific cell types possessing serotonin2 receptors, we conducted an immunocytochemical study of the rat brain using a polyclonal serotonin2 receptor antibody. Perfusion-fixed rat brain sections were processed for immunocytochemistry and reactivity was visualized using an immunoperoxidase reaction. Numerous small, round neurons were heavily labeled in the granular and periglomerular regions of the olfactory bulb. Heavy labeling of medium-sized multipolar and bipolar neurons was also seen in olfactory regions of the ventral forebrain, including the anterior olfactory nucleus and olfactory tubercle. Other regions of the basal forebrain exhibiting high levels of immunoreactivity were the nucleus accumbens, ventral pallidum, Islands of Calleja, fundus striatum and endopyriform nucleus. Immunoreactive neurons were also seen in the lateral amygdala. A dense band of small, round cells was stained in layer 2 of pyriform cortex. In neocortex, a very sparse and even distribution of bipolar and multipolar neurons was seen throughout layers II-VI. A much more faintly labeled population of oval cells was observed in the deep layer of retrosplenial and posterior cingulate cortex, and in the granular layer of somatosensory frontoparietal cortex. A moderate number of medium bipolar and multipolar cells were scattered throughout the neostriatum, and a moderate number of pyramidal and pyramidal-like cells were seen in the CA fields of the hippocampus. Diencephalic areas showing immunolabeling included the medial habenula and anterior pretectal nucleus, with less labeling in the ventral lateral geniculate. In the hindbrain, two dense populations of large multipolar cells were heavily labeled in the pedunculopontine and laterodorsal tegmental nuclei, with lesser labeling in the periaqueductal gray, superior colliculus, spinal trigeminal nucleus and nucleus of the solitary tract. Based on the distribution, localization and morphology of immunoreactive neurons in these regions, we hypothesize that subpopulations of serotonin2 containing cells may be GABAergic interneurons or cholinergic neurons. Further, the observed distribution suggests that the physiological effects of serotonin acting through serotonin2 receptors are mediated by a relatively small number of cells in the brain. These observations may have strong functional implications for the pharmacological treatment of certain neuropsychiatric disorders.     

Sex difference and testosterone modulation of pheromone-induced NeuronalFos in the Ferret's main olfactory bulb and hypothalamus

A carnivore, the ferret possesses a vomeronasal organ--accessory olfactory bulb (VNO-AOB) projection to the hypothalamus; however, little is known about its function. Pheromones in soiled bedding from estrous female ferrets or an artificial peppermint odor significantly augmented nuclear Fos protein immunoreactivity (Fos-IR), a marker of neural activation, in several main olfactory bulb (MOB) sites but not in the AOB of gonadectomized male and females. Testosterone propionate (TP) significantly augmented the MOB's neuronal Fos responses to estrous females' pheromones, but not to peppermint. Estrous odors, but not peppermint, also augmented neuronal Fos-IR in the medial preoptic area (mPOA) of female, but not male, subjects. Pheromones in soiled bedding from breeding male ferrets significantly augmented neuronal Fos-IR in the MOB and in the medial amygdala of gonadectomized, TP-treated male and female subjects. Again, male pheromones failed to influence neuronal Fos-IR in the AOB of either sex, and only females showed significant increases in neuronal Fos-IR in the lateral aspect of the ventromedial nucleus and mPOA. These results point to an essential role among higher mammals of the main olfactory epithelium-MOB projection to the hypothalamus in detecting and processing pheromones. Gonadectomized ferrets showed significant increases in sniffing behavior when placed on either female or male bedding. This occurred regardless of whether they had received TP or oil vehicle, suggesting that testosterone's facilitation of neuronal Fos responses to estrous females' odors in the MOB of both sexes cannot be attributed to increased scent gathering. Androgen receptor-IR was present in the MOB granule cell layer of male and female ferrets, raising the possibility that testosterone acts directly on these cells to augment their responsiveness to pheromones.     

Organization of the intrinsic connections of the monkey amygdaloid complex: projections originating in the lateral nucleus

We have used the anterograde tracer, Phaseolus vulgaris-leucoagglutinin (PHA-L) to study the intrinsic projections of the lateral nucleus of the Macaca fascicularis monkey amygdaloid complex. A reanalysis of the monkey lateral nucleus indicated that there are at least four distinct cytoarchitectonic divisions: dorsal, dorsal intermediate, ventral intermediate, and ventral. The major projections within the lateral nucleus originate in the dorsal, dorsal intermediate, and ventral intermediate divisions and terminate in the ventral division. The ventral division also projects to itself but does not project significantly to the other divisions of the lateral nucleus. Thus, the ventral division appears to be a site of convergence for information entering all other portions of the lateral nucleus. There are substantial regional and topographic differences in the projections from each of the lateral nucleus divisions to other amygdaloid nuclei. The dorsal division projects to all divisions of the basal and accessory basal nuclei, to the periamygdaloid cortex, the nucleus of the lateral olfactory tract, the dorsal division of the amygdalohippocampal area, and the lateral capsular nuclei. The dorsal intermediate division projects to the intermediate and parvicellular divisions of the basal nucleus, to the parvicellular division of the accessory basal nucleus, and to the periamygdaloid cortex. The ventral intermediate division projects to the magnocellular division of the accessory basal nucleus and to the parvicellular division of the basal nucleus. The major projections from the ventral division are directed to the parvicellular division of the basal nucleus, the parvicellular division of the accessory basal nucleus, the medial nucleus, and the periamygdaloid cortex. Projections from all portions of the lateral nucleus to the central nucleus are generally very light. It appears, therefore, that each division of the lateral nucleus originates topographically organized projections to the other amygdaloid areas that terminate in distinct portions of the target regions. The topographic organization of intrinsic amygdaloid projections raises the possibility that serial and parallel sensory processing may take place within the amygdaloid complex.     

Axonal connections of the medial magnocellular nucleus of the anterior neostriatum in zebra finches

The medial magnocellular nucleus of the anterior neostriatum (mMAN) is a small cortical nucleus which was previously identified as a component of the neural circuitry controlling vocal behavior in songbirds based on its efferent connection to the High Vocal Center (HVC), a major song control nucleus (Nottebohm et al. [1982] J. Comp. Neurol. 207:344-357; Bottjer et al. [1989] J. Comp. Neurol. 279:312-326). We have conducted tract tracing experiments (using wheat-germ agglutinin-horseradish peroxidase (WGA-HRP), the carbocyanine dye DiI, and biocytin) to determine the complete pattern of afferent and efferent connections of mMAN in adult male zebra finches. We confirmed the existence of an efferent projection from mMAN to HVC and discovered a novel projection to the region medial to caudal HVC called paraHVC (pHVC). Injections of retrograde tracers into mMAN showed that afferent input to mMAN originates from the dorsomedial nucleus of the posterior thalamus (DMP). Injections of DiI into DMP produced anterograde label over mMAN, thus confirming the DMP-to-mMAN projection. Interestingly, this anterograde label extended beyond the region of mMAN defined by HVC-projecting neurons into the immediately surrounding cortex. This extended terminal field of DMP efferents indicates that mMAN encompasses a core population of projection neurons surrounded by a shell of non-HVC-projecting neurons, both of which receive input from the dorsal thalamus. Analysis of retrograde DiI label resulting from DMP injections revealed two major sources of afferent input to DMP originating in regions of the archistriatum and hypothalamus. Inputs to DMP were distributed throughout the dorsal archistriatum and included the area that receives a projection from the parvicellular shell region of the lateral magnocellular nucleus of the anterior neostriatum, a song control nucleus, as well as the dorsal portion of the robust nucleus of the archistriatum, the motor-cortical output of the song control system. The projections from song control regions of the archistriatum to DMP may feed information back into telencephalic song control circuitry via the DMP-->mMAN-->HVC/pHVC pathway. The other source of afferent input to DMP is located in the external cellular stratum of the lateral hypothalamus (SCE). This newly delineated SCE-->DMP-->mMAN-->HVC/pHVC pathway is the first report of a hypothalamic brain region neuroanatomically integrated with song control circuitry. Because hypothalamic brain regions are important for homeostasis and regulating behavior, the trans-synaptic circuitry of mMAN may help to integrate information about the bird's internal state, such as sexual maturation, with song learning and production.     

Spatial organization and plasticity of the primary and secondary olfactory projections in goldfish

Crystals of the lipophilic tracer DiI were applied to discrete regions of the olfactory epithelium of goldfish to trace the primary sensory projection to the olfactory bulb. Receptors from the anterior half of the sensory sheet project primarily to glomeruli in the medial half of the bulb and receptors in the posterior half terminate mainly within the lateral half of the bulb. This pattern disappeared following ablation of selected, discrete epithelial regions. In order to investigate reorganization of secondary olfactory projections, unoperated control and unilaterally bulbectomized animals received injections of [3H]proline into the right olfactory bulb. Densities of silver grains per unit area were determined within six different forebrain nuclei in both the right and left hemispheres of each animal. Of the six areas examined, three demonstrated a significantly greater density of afferent innervation from the ipsilateral versus contralateral bulb; a difference which disappeared in two of these three regions after bulbectomy. Thus, for at least two forebrain nuclei, bulb removal caused a change in the afferent input from the spared olfactory bulb to those regions. We conclude that both primary and secondary olfactory projections in goldfish are capable of some degree of reorganization following insult.     

Internal connections in the rostral ventromedial medulla of the rat

Physiological and pharmacological data suggest that the rostral ventromedial medulla (RVM) is an important site where integration between somatic and visceral functions might occur. The aim of the present study was to describe the interconnections between various nuclei of the rostral ventromedial medulla and thus reveal the possible anatomical basis for such functional interactions. The topography of anterogradely labelled internal projections was examined following iontophoretic microinjections of Phaseolus vulgaris leucoagglutinin (PHA-L). The results revealed that the nuclei of the rostral ventromedial medulla have strong interconnections and, to varying degrees, they also have bilateral projections into the rostral ventrolateral medulla. A particularly dense projection to widespread regions of the ventral medulla was traced from the raphe obscurus. Terminals, originating from the raphe pallidus were similarly dispersed but very low density in comparison. The focus of the projections of the gigantocellular nucleus pars ventralis and pars alpha shifted from the lateral paragigantocellular nucleus towards the RVM in rostral direction. Connections from the raphe magnus were altogether restricted to the RVM and the medial aspects of the lateral paragigantocellular nucleus. The diffuse and dense intramedullary connections of the raphe obscurus suggest that it might have an important role in coordinating the activity of rostral ventral medullary cells. The raphe pallidus and the ventral gigantocellular nuclei, areas that were innervated from widespread regions of the rostral ventral medulla but gave only limited projections there, are more likely to be involved in the direct descending control of spinal activities.     

The RAF family: an expanding network of post-translational controls and protein-protein interactions

Biotinylated dextran amine was injected unilaterally into dorsal regions of the telencephalon of the weakly electric fish Gymnotus carapo in order to study the afferent and efferent connections of specific dorsal regions with ventral regions of the telencephalon and with other regions of the central nervous system. Efferent pathways from the dorsolateral area of the telencephalon project ipsilaterally to the anterior hypothalamic nucleus, the ventral thalamus and magnocellular tegmental nucleus, whose axons reach the spinal cord. Anterograde labeling showed that the central division of the dorsal telencephalon sends efferent projections through the lateral forebrain bundle towards the ipsilateral lateral and medial preglomerular nucleus, the pretectal nucleus, the optic tectum and the dorsal torus semicircularis, regions that are all involved in the processing of electrosensory and/or multisensory information. In addition, when biotinylated dextran amine was injected into the dorsal torus semicircularis, retrogradely labeled neurons were observed in the dorsocentral area of the telencephalon. The dorsocentral area is also a target of the extra-telencephalic afferents originating from rostral, lateral and medial regions of preglomerular complex. Within the telencephalon, neurons of many ventral subdivisions project ipsilaterally to the dorsocentral area. The dorsocentral, dorsolateral and dorsomedial areas are connected ipsilaterally and reciprocally. The dorsocentral area is reciprocally connected with its contralateral homologue through the anterior commissure.     

Dorsal raphe, substantia nigra and locus coeruleus: interconnections with each other and the neostriatum

Using a retrograde axonal transport method, direct projections to the neostriatum were demonstrated from the dorsal raphe nucleus, a large area of the ventral midbrain tegmentum (including the ventral tegmental area of Tsai, the substantia nigra pars compacta, reticulata and suboculomotoria), and the tegmentum ventral to the caudal red nucleus. A direct projection was also found from the mediodorsal part of the substantia nigra to the rostral part of the dorsal raphe nucleus. Projections from the entopeduncular nucleus (pallidum) and the lateral hypothalamic area to the lateral habenular nucleus, and from the latter to the dorsal raphe nucleus were also found. This habenular projection arises primarily from large neurons in the medial part of the lateral habenula and also from another group of small cells immediately adjacent to the medial habenular nucleus. A non-reciprocal connection of the dorsal raphe nucleus to the locus coernuleus was also found. On the basis of these results and the data available in the literature on the possible neurotransmitters used by these various structures, it is suggested that the dorsal raphe nucleus may play an important role in brain stem modulation of neostriatal function.     

Fast game theory coupled to slow population dynamics: the case of domestic cat populations

The distribution of a metabotropic glutamate receptor mGluR2 in the central nervous system was immunohistochemically examined in the rat and mouse with a monoclonal antibody raised against an N-terminal sequence of rat mGluR2 (amino acid residues 87-134). Neuronal cell bodies with mGluR2-like immunoreactivity (mGluR2-LI) were clearly shown in the horizontal cells of Cajal in the cerebral cortex, neurons in the triangular septal nucleus and medial mammillary nucleus, Golgi cells and the unipolar brush cells in the cerebellar cortex, and Golgi-like and unipolar brush-like cells in the cochlear nucleus. Neuropil was intensely immunostained in the accessory olfactory bulb, bed nucleus of the accessory olfactory tract, neocortex, cingulate cortex, retrosplenial cortex, subicular and entorhinal cortices, stratum lacunosum-moleculare of CA1 and CA3, molecular layer of the dentate gyrus, periamygdaloid cortex, basolateral amygdaloid nucleus, bed nucleus of the anterior commissure, caudate-putamen, accumbens nucleus, thalamic reticular nucleus, anteroventral and paraventricular thalamic nuclei, granular layer of the cerebellar cortex, anterior and ventral tegmental nuclei, granular layer of the cochlear nucleus, and parvicellular part of the lateral reticular nucleus. Many axons in the white matter and fiber bundles were also immunostained. No glial cells with mGluR2-LI were found. No particular species differences were found in the distribution pattern of mGluR2-LI between the rat and mouse. The results indicate that mGluR2 is expressed not only in somato-dendritic domain, but also in axonal domain of excitatory and inhibitory neurons.