Search results for "Septal Nuclei"
showing 10 items of 10 documents
Cannabinoid CB1 receptors in distinct circuits of the extended amygdala determine fear responsiveness to unpredictable threat.
2016
The brain circuits underlying behavioral fear have been extensively studied over the last decades. Although the vast majority of experimental studies assess fear as a transient state of apprehension in response to a discrete threat, such phasic states of fear can shift to a sustained anxious apprehension, particularly in face of diffuse cues with unpredictable environmental contingencies. Unpredictability, in turn, is considered an important variable contributing to anxiety disorders. The networks of the extended amygdala have been suggested keys to the control of phasic and sustained states of fear, although the underlying synaptic pathways and mechanisms remain poorly understood. Here, we…
Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion.
1998
The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/ substantia nigra and cen…
Distribution and targets of the relaxin-3 innervation of the septal area in the rat.
2012
Neural tracing studies have revealed that the rat medial and lateral septum are targeted by ascending projections from the nucleus incertus, a population of tegmental GABA neurons. These neurons express the relaxin-family peptide, relaxin-3, and pharmacological modulation of relaxin-3 receptors in medial septum alters hippocampal theta rhythm and spatial memory. In an effort to better understand the basis of these interactions, we have characterized the distribution of relaxin-3 fibers/terminals in relation to different septal neuron populations identified using established protein markers. Dense relaxin-3 fiber plexuses were observed in regions of medial septum containing hippocampal-proje…
Convergence of olfactory and vomeronasal projections in the rat basal telencephalon
2007
Olfactory and vomeronasal projections have been traditionally viewed as terminating in contiguous non-overlapping areas of the basal telencephalon. Original reports, however, described areas such as the anterior medial amygdala where both chemosensory afferents appeared to overlap. We addressed this issue by injecting dextran amines in the main or accessory olfactory bulbs of rats and the results were analyzed with light and electron microscopes. Simultaneous injections of different fluorescent dextran amines in the main and accessory olfactory bulbs were performed and the results were analyzed using confocal microscopy. Similar experiments with dextran amines in the olfactory bulbs plus Fl…
Effect of sertraline treatment on benzodiazepine receptors in the rat brain.
1993
In this paper we describe the modification of benzodiazepine (BDZ) binding sites in the rat brain after different times of treatment with the 5-hydroxytryptamine-(5HT) uptake blocker sertraline. We investigated the effect of 8, 15 and 30 days sertraline treatment (10 mg/kg/day, i.p.) on 3 H-flunitrazepam binding sites. In order to describe the anatomical site of action of the drug, the experiment has been carried out by means of quantitative receptor autoradiography. After 8 days of sertraline treatment, an increase of BDZ receptor density is found in the olfactory tubercle. This effect is reversed at 15 and 30 days. At 15 days of treatment, an increase is found in the anterior cingulate co…
Septal projections to nucleus incertus in the rat: Bidirectional pathways for modulation of hippocampal function
2014
Projections from the nucleus incertus (NI) to the septum have been implicated in the modulation of hippocampal theta rhythm. In this study we describe a previously uncharacterized projection from the septum to the NI, which may provide feedback modulation of the ascending circuitry. Fluorogold injections into the NI resulted in retrograde labeling in the septum that was concentrated in the horizontal diagonal band and areas of the posterior septum including the septofimbrial and triangular septal nuclei. Double-immunofluorescent staining indicated that the majority of NI-projecting septal neurons were calretinin-positive and some were parvalbumin-, calbindin-, or glutamic acid decarboxylase…
Septal complex of the telencephalon of the lizardPodarcis hispanica. II. afferent connections
1997
The afferent connections to the septal complex were studied in the lizard Podarcis hispanica (Lacertidae) by means of a combination of retrograde and anterograde tracing. The results of these experiments allow us to classify the septal nuclei into three main divisions. The central septal division (anterior, lateral, dorsolateral, ventrolateral, and medial septal nuclei plus the nucleus of the posterior pallial commissure) receives a massive, topographically organized, cortical projection (medial, dorsal, and ventral areas) and widespread afferents from the tuberomammillary hypothalamus and the basal telencephalon. Moreover, it receives discrete projections from the dorsomedial anterior thal…
The septal complex of the telencephalon of the lizardPodarcis hispanica. I. chemoarchitectonical organization
1995
In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertidae). Histochemical and immunohistochemical techniques were used to define the distribution of zinc (Timm stain), acetyl cholinesterase (AChase), gamma-aminobutyric acid (GABA), tyrosine hydroxylase (TH), dopamine (DA), serotonin (5-HT), and two neuropeptides: leu-enkephalin (L-ENK) and substance P (SP). These reactions delineate a coherent map of nine septal nuclei that are named with a topographical nomenclature: anterior, lateral, ventromedial, medial, dorsolateral, ventrolateral, and dorsal septal nuclei, nucleus septalis impar, and nucleus of the posterior pallial commissure. The anterior se…
Serotonergic modulation of hippocampal acetylcholine release after long-term neuronal grafting
2000
Adult female rats sustained aspirative fimbria-fornix lesions and, 2 weeks later, received intrahippocampal grafts of fetal septal or mixed septal-raphe cell suspensions. Twenty-four months later, the extracellular concentration of hippocampal acetylcholine (ACh) was determined by microdialysis. Basal ACh levels (5-65 fmol/5 microl sham-operated rats) were strongly reduced after lesioning (3-7 fmol/5 microl). In septally transplanted and septal-raphe co-transplanted rats, hippocampal ACh concentrations were restored to near-normal levels (15-25 fmol/5 microl), indicating long-term functional survival of hippocampal transplants. After administration of citalopram (100 microM by infusion) and…
Modulation of hippocampal acetylcholine release after fimbria-fornix lesions and septal transplantation in rats
1997
Abstract Female Long–Evans rats sustained electrolytic lesions of the fimbria and the dorsal fornix causing a partial lesion of the septohippocampal pathway. Two weeks later, the rats received intra-hippocampal grafts of fetal septal cell suspensions. Nine to twelve months later, the release of acetylcholine (ACh) in the hippocampus of sham-operated, lesion-only and grafted rats was measured by microdialysis. The extent of cholinergic (re)innervation was determined by acetylcholinesterase (AChE) staining and densitometry. In both lesion-only and grafted rats, the ratio of ACh release to AChE staining intensity was increased as compared to sham-operated rats, indicating a loss of endogenous …