Behavioural brain research
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The behavioral inhibition system (BIS) and the behavioral activation system (BAS) are two fundamental motivational systems which are not only responsible for affective states, behavior and personality, but also related to predispositions for various forms of psychopathology. A wide range of previous studies revealed sex differences in both BIS/BAS and affective disorders (e.g., anxiety disorder) and externalizing disorders (e.g., addictive and impulsive behaviors), and a close link might exist between them. It remains to be clarified, however, whether the relationships between neuroanatomical characteristics and BIS/BAS exhibit sex differences. ⋯ Results showed that females displayed a negative correlation between BIS sensitivity and rGMV in the parahippocampal gyrus (PHG), as well as positive correlations between BAS sensitivity and rGMV in the ventromedial prefrontal cortex (vmPFC) and inferior parietal lobule (IPL), whereas males showed the opposite pattern. These findings suggest that the brain regions associated with processing of negative emotions (PHG) and reward-related information (vmPFC and IPL) may contribute to sex-related differences in rGMV correlates of BIS and BAS, respectively. The present findings demonstrated the evidence of sex-linked neuroanatomical background of BIS and BAS among non-clinical subjects and might encourage future research into the gender-specific relationships between BIS/BAS and related affective disorders and externalizing disorders.
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Over the last decade accumulating evidence suggests that brain dopamine (DA) has a role in depression, particularly given the high comorbidity of depression with Parkinson's Disease (PD) and the antidepressant effects of the DA receptor subtype 3 (D3R) agonist pramipexole. The present study assesses the role of D3R in depression. Here we hypothesized that D3R mediates the antidepressant effects of DA. ⋯ Whereas D3R deficient mice did not show significant alterations in locomotion when tested in the openfield, these animals showed anxiety-like symptoms measured as a significant increase in thigmotaxis at the openfield and a significantly lower time spent in the lit compartment at the light/dark exploration test. D3RKO animals also showed depressive-like symptoms as measured by increased immobility time in the Porsolt forced swim test and the tail suspension test, as well as anhedonia measured in the non-motor dependent sucrose test. In conclusion, D3R deficiency results in anxiety-like and depressive-like symptoms that cannot be attributed to motor dysfunction.
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Within the Pavlovian conditioning framework, extinction is a procedure in which, after conditioning, the conditioned stimulus (CS) is repeatedly presented without the unconditioned stimulus (US). During this procedure the conditioned response (CR) is gradually attenuated. It has been suggested that extinction during the early stages of ontogeny is a qualitatively different process from extinction in adulthood: during infancy, extinction may result in erasure of the memory, while during adulthood extinction involves new learning. ⋯ Extinction produced changes in the expression of freezing, grooming and exploration, and the clearest evidence of spontaneous recovery came from the analysis of freezing behavior. The pattern of behavior observed during extinction is compatible with theoretical approaches which consider different dynamic behavioral systems, and it also fit in well with a molar approach to the analysis of behavior, which considers that extinction involves a transition from one allocation of time among behaviors to another allocation, rather than a loss of strength in any particular discrete response. These results have implications for the study of extinction during infancy, since they are compatible with the hypothesis that the original memory survives extinction, and highlight the importance of control conditions for detecting this effect during this ontogenetic period.
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We previously found that juvenile pituitary adenylate cyclase-activating polypeptide (PACAP)-knockout (PACAP(-/-)) mice reared in an enriched environment (EE) for 4 weeks showed attenuated hyperactivity, jumping behavior, impairments in social interaction, and depression-like behavior. The present study examined the effects of EE on memory function and memory-related protein levels in PACAP(-/-) mice. Eight-week-old PACAP(-/-) mice displayed fear memory dysfunction in a contextual fear conditioning test and cognitive impairments in a novel object recognition test. ⋯ Increased levels of NR2B, phospho-ERK, phospho-CaMKII and BDNF were not observed 2 weeks after a return to housing in a SE. These findings suggest that living in an EE engenders long-lasting reductions in memory impairments in PACAP(-/-) mice. The present study also implies that increases in hippocampal memory-related protein and BDNF levels are responsible for the beneficial effects of an EE, but not for the maintenance of these effects.
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Randomized Controlled Trial Comparative Study
Effects of mild to moderate sedation on saccadic eye movements.
Sedatives alter the metrics of saccadic eye movements. If these effects are nonspecific consequences of sedation, like drowsiness and loss of attention to the task, or differ between sedatives is still unresolved. A placebo-controlled multi-step infusion of one of three sedatives, propofol or midazolam, both GABA-A agonists, or dexmedetedomidine, an α2-adrenergic agonist, was adopted to compare the effects of these three drugs in exactly the same experimental conditions. 60 healthy human volunteers, randomly divided in 4 groups, participated in the study. ⋯ Midazolam, and to a less extent, propofol, caused saccades to become increasingly hypometric. Dexmedetedomidine had less impact on saccadic metrics and presented no changes in saccadic gain. Suppression of the sympathetic system associated with dexmedetomidine has different effects on eye movements from the increased activity of the inhibitory GABA-A receptors by propofol and midazolam even when the subjects reported similar sedation level.