Neuroscience
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Placebo treatment can alter brain activation in regions implicated in affective processing and cognitive control of emotions. This functional magnetic resonance imaging (fMRI) study investigated whether a placebo can additionally modulate visual cortex activity and connectivity during affective picture perception. ⋯ This was accompanied by a reduced activation of the primary visual cortex, which showed reduced interaction with the amygdala and the insula. Accordingly, placebos are able to affect basic perceptive processes.
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To explore the effects of modulating autophagy on neuroamyloidogenesis in an ischemic stroke model of cultured neuroblastoma 2a (N2a)/Amyloid precursor protein (APP)695 cells. ⋯ Our data suggested that down-regulating autophagy may inhibit ischemia-induced neuroamyloidogenesis via suppressing the activation of NF-κB pathway. This study might help us to find a new therapeutic strategy to prevent brain ischemic damage and depress the risk of post-stroke dementia.
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Cannabinoid receptor type 1 (CB1)-dependent signaling in the brain is known to modulate food intake. Recent evidence has actually shown that CB1 can both inhibit and stimulate food intake in fasting/refeeding conditions, depending on the specific neuronal circuits involved. However, the exact brain sites where this bimodal control is exerted and the underlying neurobiological mechanisms are not fully understood yet. ⋯ Furthermore, local CB1 blockade in the PVN also increases the orexigenic effect of the gut hormone ghrelin in animals fed ad libitum. At the electrophysiological level, CB1 blockade in slices containing the PVN potentiates the decrease of the activity of PVN neurons induced by long-term application of ghrelin. Hence, the PVN is (one of) the site(s) where signals associated with the body's energy status determine the direction of the effects of endocannabinoid signaling on food intake.
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The countermanding paradigm investigates the ability to withhold a response when a stop signal is presented occasionally. The race model (Logan and Cowan, 1984) was developed to account for performance in humans and to estimate the stop signal response time (SSRT). This model has yet to be fully validated for countermanding performance in rats. ⋯ Amphetamine (AMPH) (0.25, 0.5mg/kg) resulted in faster go trial RTs, baseline-dependent changes in SSRT and attenuated response adjustments. These findings demonstrate that the race model of countermanding performance, applied successfully in human and nonhuman primate models, can be employed in the countermanding performance of rodents. This is the first study to reveal response adjustments and AMPH-induced alterations of response adjustments in rodent countermanding.
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The Roman Low- and High-Avoidance rat strains (RLA-I vs RHA-I) have been bidirectionally selected and bred according to their performance in the two-way active avoidance response in the shuttle-box test. Numerous studies have reported a pronounced divergence in emotionality between the two rat strains including differences in novelty seeking, anxiety, stress coping, and susceptibility to addictive substances. However, the underlying molecular mechanisms behind these divergent phenotypes are not known. ⋯ To differentiate between mGlu2 and mGlu3 receptor protein levels, these were further studied using western blotting, which showed non-detectable levels of mGlu2 receptor protein in RHA rats, while no differences were observed for mGlu3 receptor protein levels. Collectively, these data show general congenital differences in the serotonergic system and a pronounced difference in mGlu2 receptor protein levels. We suggest that the differences in the serotonergic system may mediate some of the phenotypic characteristics in this strain such as hyper-impulsivity and susceptibility to drug addiction.