Search results for "Amygdala"
showing 10 items of 169 documents
Role of the amygdala in antidepressant effects on hippocampal cell proliferation and survival and on depression-like behavior in the rat
2021
The stimulation of adult hippocampal neurogenesis by antidepressants has been associated with multiple molecular pathways, but the potential influence exerted by other brain areas has received much less attention. The basolateral complex of the amygdala (BLA), a region involved in anxiety and a site of action of antidepressants, has been implicated in both basal and stress-induced changes in neural plasticity in the dentate gyrus. We investigated here whether the BLA modulates the effects of the SSRI antidepressant fluoxetine on hippocampal cell proliferation and survival in relation to a behavioral index of depression-like behavior (forced swim test). We used a lesion approach targeting th…
Pattern analyses reveal separate experience-based fear memories in the human right Amygdala
2017
Learning fear via the experience of contingencies between a conditioned stimulus (CS) and an aversive unconditioned stimulus (US) is often assumed to be fundamentally different from learning fear via instructions. An open question is whether fear-related brain areas respond differently to experienced CS–US contingencies than to merely instructed CS–US contingencies. Here, we contrasted two experimental conditions where subjects were instructed to expect the same CS–US contingencies while only one condition was characterized by prior experience with the CS–US contingency. Using multivoxel pattern analysis of fMRI data, we found CS-related neural activation patterns in the right amygdala (but…
Amygdala pathology in Parkinson's disease.
1994
The amygdala undergoes severe pathological changes during the course of Parkinson's disease (PD). Lewy bodies and Lewy neurites are distributed in a specific manner throughout the nuclear complex. The lesional pattern displays only minor interindividual variation. The most prominent changes occur in the accessory cortical and central nuclei. The cortical, accessory basal and granular nuclei show less severe alterations, while the basal and lateral nuclei, as well as the intercalated cell masses, generally remain uninvolved. The amygdala receives a broad range of afferents, allowing integration of exteroceptive information with interoceptive data. It generates major projections to the isocor…
Effect of recurrent yohimbine on immediate and post-hoc behaviors, stress hormones, and energy homeostatic parameters
2013
Evidence from experimental models has suggested that acute activation of brain stress and anxiety pathways impacts subsequent behaviors that are mediated or modulated by limbic circuitry. There have been limited investigations of prior or chronic activation of these pathways on subsequent limbic-mediated behaviors. In this study, we tested whether recurrent administration of the anxiogenic compound yohimbine (YOH) could have post-injection effects on brain activation, stress hormones, and performance in sucrose self-administration and startle response paradigms. Rats received six injections across two weeks of either 2mg/kg YOH or saline. Behavioral evaluation confirmed the continued effica…
c-fos expression, behavioural, endocrine and autonomic responses to acute social stress in male rats after chronic restraint: modulation by serotonin
2000
The effects in male rats of serotonin depletion (using the neurotoxin 5,7-dihydroxytryptamine) on the cross-sensitization of an acute social stress (defeat by a larger resident male) by previous repeated restraint stress (10 days, 60 min per day) was studied. Previous restraint increased freezing responses during social defeat in sham-operated rats, but this was not observed in those with depleted serotonin (83% or more in different regions of the brain). In contrast, neither heart rate (tachycardia) nor core temperature responses (hyperthermia) were accentuated in previously restrained rats (i.e. neither showed heterotypical sensitization), and neither adapted to repeated restraint (there …
Chronic restraint stress and chronic corticosterone treatment modulate differentially the expression of molecules related to structural plasticity in…
2004
Stress and stress-related hormones induce structural changes in neurons of the adult CNS. Neurons in the hippocampus, the amygdala and the prefrontal cortex undergo neurite remodeling after chronic stress. In the hippocampus some of these effects can be mimicked with chronic administration of adrenal steroids. These changes in neuronal structure may be mediated by certain molecules related to plastic events such as the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). The expression of PSA-NCAM persists in the adult hippocampus and it is up-regulated after chronic stress. The piriform cortex also displays considerable levels of PSA-NCAM during adulthood and indirect evide…
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…
Central serotonin depletion modulates the behavioural, endocrine and physiological responses to repeated social stress and subsequent c-fos expressio…
1999
Abstract Intraspecific confrontation has been used to study effect of depleting central serotonin on the adaptation of male rats to repeated social stress (social defeat). Four groups of adult male rats were used (serotonin depletion/sham: stressed; serotonin depletion/sham: non-stressed). Central serotonin was reduced (by 59–97%) by a single infusion of the neurotoxin 5,7-dihydroxtryptamine (150 μg) into the cerebral ventricles; levels of dopamine and noradrenaline were unaltered (rats received appropriate uptake blockers prior to neurotoxic infusions). Sham-operated animals received solute only. Rats were then either exposed daily for 10 days to a second larger aggressive male in the latt…
Selective dopaminergic lesions of the ventral tegmental area impair preference for sucrose but not for male sexual pheromones in female mice
2006
The role of the meso-accumbens dopaminergic pathway in reward-related behaviours is the subject of intense investigation. In this regard, here we analyse the effects of specific lesions of dopaminergic cells of the ventral tegmental area (VTA) of female mice on two goal-directed behaviours, namely sucrose preference (intake of sucrose solution vs. water) and preference for male sexual pheromones (exploration of male-soiled vs. clean bedding). The results indicate that partial lesions of the VTA that impair neither locomotion nor general exploratory behaviour reduce the preference for sucrose (over a 48-h period) but do not alter the innate attraction that females display for male sexual phe…
Chronic antidepressant treatment induces contrasting patterns of synaptophysin and PSA-NCAM expression in different regions of the adult rat telencep…
2007
Structural modifications occur in the brain of severely depressed patients and they can be reversed by antidepressant treatment. Some of these changes do not occur in the same direction in different regions, such as the medial prefrontal cortex, the hippocampus or the amygdala. Differential structural plasticity also occurs in animal models of depression and it is also prevented by antidepressants. In order to know whether chronic fluoxetine treatment induces differential neuronal structural plasticity in rats, we have analyzed the expression of synaptophysin, a protein considered a marker of synaptic density, and the expression of the polysialylated form of the neural cell adhesion molecul…