Neuroscience
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Because of their difficulties with figurative language in conversation, it is commonly thought that individuals with autism spectrum disorder (ASD) do not understand figurative meaning. However, recent research indicates that individuals with and without ASD are similar in the first two stages of metaphor comprehension, up to and including successful generation of the figurative meaning. In the current study, we used a sentence decision task to evaluate the subsequent stage of metaphor comprehension, the selection stage, which requires suppression/inhibition of the unintended meaning as part of selecting the intended meaning. fMRI activation and functional connectivity were used to compare the selection stage of metaphor comprehension between high-functioning individuals with ASD and carefully matched controls. ⋯ There was a novel finding of maintenance of subcortical-subcortical connectivity in the ASD group, specific to the selection condition, despite differences in cortically involved connections. Reduced cortical-subcortical connectivity in the ASD group compared to controls may reflect a more global impairment in cognitive control pathways, while consistent subcortical-subcortical connectivity may reflect systemic inflexibility or preserved subcortical function and dissociation between subcortical and cortical systems. Further investigation is required.
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Choline is essential to the development and function of the central nervous system and supplemental choline during development is neuroprotective against a variety of insults, including neurotoxins like dizocilpine (MK-801). MK-801 is an NMDA receptor antagonist that is frequently used in rodent models of psychological disorders, particularly schizophrenia. At low doses, it causes cognitive impairments, and at higher doses it induces motor deficits, anhedonia, and neuronal degeneration. ⋯ Using doublecortin and Ki67 to mark neurogenesis and cell division, respectively, in the hippocampus, we found that prenatal choline supplementation, in the face of MK-801 toxicity, protected against reduced hippocampal plasticity. Taken together, the current findings suggest that prenatal choline supplementation protects against a variety of behavioral and neural pathologies induced by the neurotoxin, MK-801. This research contributes to the growing body of evidence supporting the robust neuroprotective capacity of choline.
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Corticotropin-releasing factor (CRF) signaling through CRF receptor 1 (CRFR1) regulates autonomic, endocrine and behavioral responses to stress and has been implicated in the pathophysiology of several disorders including anxiety, depression, and addiction. Using a validated CRFR1 reporter mouse line (bacterial artificial chromosome identified by green fluorescence protein (BAC GFP-CRFR1)), we investigated the distribution of CRFR1 in the developing mouse forebrain. Distribution of CRFR1 was investigated at postnatal days (P) 0, 4, and 21 in male and female mice. ⋯ We report a sexually dimorphic expression of CRFR1 within the rostral portion of the anteroventral periventricular nucleus of the hypothalamus (AVPV/PeN), a region known to regulate ovulation, reproductive and maternal behaviors. Females had a greater number of CRFR1-GFP-ir cells at all time points in the AVPV/PeN and CRFR1-GFP-ir was nearly absent in males by P21. Overall, alterations in CRFR1-GFP-ir distribution based on age and sex may contribute to observed age- and sex-dependent differences in stress regulation.
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Successful response inhibition relies on the suppression of motor cortex activity. The striatum has previously been linked to motor cortex suppression during the act of inhibition (reactive), but activation was also seen during anticipation of stop signals (proactive). More specifically, striatal activation increased with a higher stop probability. ⋯ We found that striatal activity during reactive inhibition was higher when subjects expected stop signals. These results help explain conflicting findings of previous studies on the association between striatal activation and inhibition, since we demonstrate a crucial role of the subjects' expectation of a stop signal and thus their ability to prepare for a stop in advance. In conclusion, the current results show for the first time that striatal contributions to reactive response inhibition are, in part, related to subjective anticipation.
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Better cognitive performance and greater cortical and hippocampal volume have been observed in individuals who undertook aerobic exercise during childhood and adolescence. One possible explanation for these beneficial effects is that juvenile physical exercise enables better neural development and hence more cells and neuronal circuitries. It is probable that such effects occur through intracellular signaling proteins associated with cell growth, proliferation and survival. ⋯ Results showed that physical exercise increases the number of neuronal and non-neuronal cortical cells and hippocampal neuronal cells in adolescent rats. Moreover, mTOR overexpression was found in the cortical region of exercised adolescent rats. These findings indicate a significant cellular proliferative effect of aerobic exercise on the cerebral cortex in postnatal development.