Search results for "olfactory tubercle"
showing 10 items of 25 documents
Segregated pathways to the vomeronasal amygdala: differential projections from the anterior and posterior divisions of the accessory olfactory bulb.
2007
Apically and basally located receptor neurons in the vomeronasal sensory epithelium express G(i2 alpha)- and G(o alpha)-proteins, V1R and V2R vomeronasal receptors, project to the anterior and posterior accessory olfactory bulb and respond to different stimuli, respectively. The extent to which secondary projections from the two portions of the accessory olfactory bulb are convergent in the vomeronasal amygdala is controversial. This issue is addressed by using anterograde and retrograde tract-tracing methods in rats including electron microscopy. Injections of dextran-amines, Fluoro Gold, cholera toxin-B subunit and Fast Blue were delivered to the anterior and posterior accessory olfactory…
Olfactory and cortical projections to bulbar and hippocampal adult-born neurons
2015
New neurons are continually generated in the subependymal layer of the lateral ventricles and the subgranular zone of dentate gyrus during adulthood. In the subventricular zone, neuroblasts migrate a long distance to the olfactory bulb where they differentiate into granule or periglomerular interneurons. In the hippocampus, neuroblasts migrate a short distance from the subgranular zone to the granule cell layer of the dentate gyrus to become granule neurons. In addition to the short-distance inputs, bulbar interneurons receive long-distance centrifugal afferents from olfactory-recipient structures. Similarly, dentate granule cells receive differential inputs from the medial and lateral ento…
Sexual pheromones and the evolution of the reward system of the brain: the chemosensory function of the amygdala.
2008
The amygdala of all tetrapod vertebrates receives direct projections from the main and accessory olfactory bulbs, and the strong similarities in the organization of these projections suggest that they have undergone a very conservative evolution. However, current ideas about the function of the amygdala do not pay sufficient attention to its chemosensory role, but only view it as the core of the emotional brain. In this study, we propose that both roles of the amygdala are intimately linked since the amygdala is actually involved in mediating emotional responses to chemical signals. The amygdala is the only structure in the brain receiving pheromonal information directly from the accessory …
Hierarchical cross-scale analysis identifies parallel ventral striatal networks coding for dynamic and stabilized olfactory reward predictions
2021
SUMMARYThe unbiased identification of brain circuits responsible for behavior and their local cellular computations is a challenge for neuroscience. We establish here a hierarchical cross-scale approach from behavioral modeling and fMRI in task-performing mice to cellular network dynamics to identify how reward predictions are represented in the forebrain upon olfactory conditioning. fMRI identified functional segregation in reward prediction and error computations among olfactory cortices and subcortical circuits. Among them, the olfactory tubercle contributed both to dynamic reward predictions and prediction error. In this region, cellular recordings revealed two parallel neuronal populat…
Afferent and efferent connections of the olfactory bulbs in the lizard Podarcis hispanica.
1991
The connections of the olfactory bulbs of Podarcis hispanica were studied by tract-tracing of injected horseradish peroxidase. Restricted injections into the main olfactory bulb (MOB) resulted in bilateral terminallike labeling in the medial part of the anterior olfactory nucleus (AON) and in the rostral septum, lateral cortex, nucleus of the lateral olfactory tract, and ventrolateral amygdaloid nucleus. Bilateral retrograde labeling was found in the rostral lateral cortex and in the medial and dorsolateral AON. Ipsilaterally the dorsal cortex, nucleus of the diagonal band, lateral preoptic area, and dorsolateral amygdala showed labeled cell bodies. Retrogradely labeled cells were also foun…
Hypothalamus-olfactory system crosstalk: orexin a immunostaining in mice
2012
It is well known that olfaction influences food intake, and conversely, that an individual’s nutritional status modulates olfactory sensitivity. However, what is still poorly understood is the neuronal correlate of this relationship, as well as the connections between the olfactory bulb and the hypothalamus. The goal of this report is to analyze the relationship between the olfactory bulb and hypothalamus, focusing on orexin A immunostaining, a hypothalamic neuropeptide that is thought to play a role in states of sleep/wakefulness. Interestingly, orexin A has also been described as a food intake stimulator. Such an effect may be due in part to the stimulation of the olfactory bulbar pathway…
Amygdaloid projections to the ventral striatum in mice: direct and indirect chemosensory inputs to the brain reward system
2011
Rodents constitute good models for studying the neural basis of socio-sexual behaviour. Recent findings in mice have revealed the molecular identity of the some pheromonal molecules triggering intersexual attraction. However, the neural pathways mediating this basic socio-sexual behaviour remain elusive. Since previous work indicates that the dopaminergic tegmento-striatal pathway is not involved in pheromone reward, the present report explores alternative pathways linking the vomeronasal system with the tegmento-striatal system (the limbic basal ganglia) by means of tract-tracing experiments studying direct and indirect projections from the chemosensory amygdala to the ventral striato-pall…
Subcellular localization of m2 muscarinic receptors in GABAergic interneurons of the olfactory bulb
2000
We analysed the ultrastructural distribution of the m2 muscarinic receptor (m2R) in the rat olfactory bulb (OB) using immunohistochemical techniques and light and electron microscopy. m2R was differentially distributed within the cellular compartments of gamma-aminobutyric acid (GABA)ergic bulbar interneurons. It is located in the gemmules of granule cells and in the synaptic loci of the interneurons of the external plexiform layer, suggesting that m2R activation could modulate the release of GABA from these interneurons onto principal cells by a presynaptic mechanism. By contrast, the receptor appears in the somata and dendritic trunks of second-order short-axon interneurons located in the…
Vomeronasal inputs to the rodent ventral striatum.
2008
Vertebrates sense chemical signals through the olfactory and vomeronasal systems. In squamate reptiles, which possess the largest vomeronasal system of all vertebrates, the accessory olfactory bulb projects to the nucleus sphericus, which in turn projects to a portion of the ventral striatum known as olfactostriatum. Characteristically, the olfactostriatum is innervated by neuropeptide Y, tyrosine hydroxylase and serotonin immunoreactive fibers. In this study, the possibility that a structure similar to the reptilian olfactostriatum might be present in the mammalian brain has been investigated. Injections of dextran-amines have been aimed at the posteromedial cortical amygdaloid nucleus (th…
Induction of c-fos gene expression by the selective sigma receptor ligand EMD 57445 in rat brain.
1996
Based on animal studies it has been reasoned that ligands to sigma binding sites might be effective in the treatment of schizophrenic disorders and may also be used to investigate this largely elusive disorder on a molecular level. Expression patterns of c-fos in rat brain were studied following treatment with single doses of the sigma ligand EMD 57445 (0.3, 1, 3, 30 mg/kg s.c.). Specific c-fos gene expression was detected at all concentrations tested in various cortical areas. The signals observed were dose-dependent with the highest intensities in the piriform cortex. Strong signals were also detected in hippocampal areas CA 1,2,3 and the gyrus dentatus, as well as in the medial habenula …