Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
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The ability to voluntarily self-regulate negative emotion is essential to a healthy psyche. Indeed, a chronic incapacity to suppress negative emotion might be a key factor in the genesis of depression and anxiety. Regarding the neural underpinnings of emotional self-regulation, a recent functional neuroimaging study carried out by our group has revealed that the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex are involved in voluntary suppression of sexual arousal. As few things are known, still, with respect to the neural substrate underlying volitional self-regulation of basic emotions, here we used functional magnetic resonance imaging to identify the neural circuitry associated with the voluntary suppression of sadness. ⋯ These results confirm the key role played by the DLPFC in emotional self-regulation. They also indicate that the right DLPFC and right OFC are components of a neural circuit implicated in voluntary suppression of sadness.
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Neuropsychopharmacology · Feb 2003
Enhanced morphine preference following prolonged abstinence: association with increased Fos expression in the extended amygdala.
We previously found that chronically morphine-pretreated, abstinent rats show stronger preferences for morphine-associated environments than placebo-pretreated rats. Here we show that this increased preference persisted for at least 5 weeks after withdrawal of chronic morphine. To determine brain regions involved in this behavior, we examined neural activation (as indexed by Fos-like proteins) induced by a morphine-conditioned place preference test. ⋯ Chronically morphine-pretreated (M) rats that exhibited enhanced morphine preference 5 weeks after morphine withdrawal showed significantly greater Fos in all the same areas except the BNST-DL relative to conditioned P or nonconditioned M rats. Place preference measures and Fos expression were positively correlated in the Cg and ABL, for conditioned P animals, and in the Cg, ABL and BNST-VL for conditioned M animals. These results indicate a relationship between place preference behavior and neural indices of activation in the forebrain in response to morphine-conditioned cues that may be chronically modulated by prior morphine exposure.
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Neuropsychopharmacology · Jan 2003
Chronic exposure to cold stress alters electrophysiological properties of locus coeruleus neurons recorded in vitro.
Chronic stress exposure can alter central noradrenergic function. Previously, we reported that in chronically cold-exposed rats the release of norepinephrine and electrophysiological activation of locus coeruleus (LC) neurons is enhanced in response to multiple excitatory stimuli without alterations in basal activity. In the present studies, we used in vitro intracellular recording techniques to explore the effect of chronic cold exposure on the basal and evoked electrophysiological properties of LC neurons in horizontal slices of the rat brainstem. ⋯ These data demonstrate that the stress-evoked sensitization of LC neurons observed in vivo is at least in part maintained in the slice preparation and suggest that alterations in electrophysiological properties of LC neurons contribute to the chronic stress-induced sensitization of central noradrenergic function observed in vivo. Furthermore, the present data suggest that an alteration in autoinhibitory control of LC activity is involved in the chronic stress-induced alterations. The enhanced functional capacity of LC neurons following cold exposure of rats may represent a unique model to study the mechanisms underlying the alterations in central noradrenergic function observed in humans afflicted with mood and anxiety disorders.
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Neuropsychopharmacology · Oct 2002
Randomized Controlled Trial Clinical TrialRepetitive transcranial magnetic stimulation (rTMS) in major depression: relation between efficacy and stimulation intensity.
Repetitive transcranial magnetic stimulation (rTMS) has been found to exert modest to substantial antidepressant effects in the majority of prior clinical studies. As effect sizes and stimulation conditions have varied greatly, controversy persists regarding effective stimulation parameters (e.g. intensity, frequency, localization). In the present controlled study, we investigated whether the antidepressant efficacy of rTMS may be related to the stimulation intensity applied. ⋯ A 30% to 33% reduction of baseline depression scores was observed after rTMS at MT intensity. Similarly, groups differed significantly regarding the clinical course after rTMS with the lowest number of antidepressant interventions and the shortest hospital stay in the MT intensity group. These findings support the hypothesis of a relationship between stimulation intensity of rTMS and its antidepressant efficacy.
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Neuropsychopharmacology · Sep 2002
Neurokinins activate local glutamatergic inputs to serotonergic neurons of the dorsal raphe nucleus.
It has been proposed that antidepressant effects of neurokinin NK(1) receptor blockade may result from an increase in serotonin (5-HT) transmission. However, the mechanism by which neurokinins influence 5-HT neurons is not known. In this study, local NK(1) and NK(3) receptor-mediated responses in 5-HT neurons of the dorsal raphe nucleus (DRN) were studied using intracellular recording in rat brain slices. ⋯ The SP- and NKB-induced EPSCs were preferentially blocked by NK(1) and NK(3) antagonists, and there was minimal cross-desensitization between agonists at the two receptors. We conclude that neurokinins, via distinct NK(1) and NK(3) receptors, could promote 5-HT transmission, at least in part, by exciting a local population of glutamatergic inputs to 5-HT neurons in the DRN. However, these local excitatory effects, viewed within the context of the global effects of neurokinins on 5-HT neurons, reveal important differences between the functional role of NK(1) and NK(3) receptors.