Behavioural brain research
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Previous studies using resting-state functional magnetic resonance imaging (fMRI) have found abnormal spontaneous neural activity in patients with major depressive disorder (MDD). Yet, the frequency-dependent neural activity in MDD is largely unknown. Here, we used resting-state fMRI and regional homogeneity (ReHo) methods to investigate spontaneous neural activity in specific frequency bands of 31 MDD patients and 31 age-, gender- and education-matched healthy controls. ⋯ Compared to controls, MDD patients showed increased ReHo in the middle frontal gyrus (MFG) and decreased ReHo in the fusiform and postcentral gyrus at the typical band. Importantly, MDD patients showed increased ReHo in the middle occipital gyrus (MOG) and decreased ReHo in the anterior cingulate cortex (ACC), inferior frontal gyrus (IFG), superior frontal gyrus (SFG) and the bilateral thalamus in the slow-4 band, while they showed increased ReHo in the medial prefrontal cortex (mPFC) in the slow-5 band. Our results suggest that the abnormality of ReHo in MDD is associated with the frequency band and that future studies should take frequency band effect into account when examining spontaneous neural activity.
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Euthanasia by anesthetic agents is commonly performed prior to tissue collection in order to minimize pain and distress to the animal. However, depending on their mechanism of action as well as administration regimen, different methods of anesthesia may trigger an acute stress response through engaging the hypothalamic-pituitary-adrenal (HPA) axis, which can impact numerous other physiological processes that the researcher may wish to examine as endpoints. ⋯ We conclude that collection methods can influence stress-related physiological endpoints in female rats and the potential influence of even brief anesthesia as well as sex differences in response to anesthesia should be evaluated during the experimental design process and data interpretation. This finding is particularly important in light of new NIH standards regarding sex and reproducibility, and care should be taken to be certain that sex differences in endpoints of interest are not an artifact of sex differences in response to collection paradigms.
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Limitations of preclinical models of human memory contribute to the pervasive view that rodent models do not adequately predict therapeutic efficacy in producing cognitive impairments or improvements in humans. We used a source-memory model (i.e., a representation of the origin of information) we developed for use in rats to evaluate possible drug-induced impairments of both spatial memory and higher order memory functions in the same task. Memory impairment represents a major barrier to use of NMDAR antagonists as pharmacotherapies. ⋯ Thus, source memory was more vulnerable than spatial memory to impairment. By contrast, PSD95-nNOS inhibitors, IC87201 and ZL006, administered at doses that are behaviorally effective in rats, spared source memory, spatial memory, and motor function. Thus, PSD95-nNOS inhibitors are likely to exhibit favorable therapeutic ratios compared to NMDAR antagonists.
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Long-term intermittent hypoxia (IH) is a characteristic hallmark of obstructive sleep apnea (OSA) and causes most of the neurological aspects of OSA, such as spatial memory and learning deficits. These deficits are accompanied by an increase in oxidative stress and inflammation in brain areas involved in cognition, such as the hippocampus, particularly in children. Resveratrol is a natural polyphenolic compound with potent antioxidant, anti-inflammatory and neuroprotective properties. ⋯ Resveratrol ameliorates IH-induced anxiety and spatial learning deficits through multiple beneficial effects on hippocampal oxidative pathways that involve decreased expression of the p47Phox subunit of NADPH oxidase. Hence, the potential therapeutic role of resveratrol in OSA may be utilized in the near future and deserves further exploration.
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Development of the brain includes periods which can be critical for its normal maturation. The present study investigates specifically vulnerable peri-/postnatal periods in mice which are essential for understanding the etiology behind radiation induced neurotoxicity and functional defects, including evaluation of neurotoxicity between sexes or commonly used laboratory mouse strains following low/moderate doses of ionizing radiation (IR). Male Naval Medical Research Institute (NMRI) mice, whole body irradiated to a single 500 mGy IR dose, on postnatal day (PND) 3 or PND 10 showed an altered adult spontaneous behaviour and impaired habituation capacity, whereas irradiation on PND 19 did not have any impact on the studied variables. ⋯ The present study shows that exposure to low/moderate doses of IR during critical life stages might be involved in the induction of neurological/neurodegenerative disorder/disease. A specifically vulnerable period for radiation induced neurotoxicity seems to be around PND 3-10 in mice. Further studies are needed to investigate mechanisms involved in induction of developmental neurotoxicity following low-dose irradiation.