Neuroscience
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Primary visual cortex, the first cortical stage of visual information processing, is represented by diverse functional maps that demonstrate the selectivity for specific visual features such as spatial frequency (SF). Although the local organization of SF maps in cat area 17 (A17) has been largely investigated, the global arrangement remains elusive. ⋯ In particular, we found the highest SF preference within the global distribution concentrated around the horizontal meridian. These results significantly contribute to a more comprehensive understanding of the SF organization in visual cortex.
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Alcoholism is a relapsing disorder with limited treatment options, in part due to our limited understanding of the disease etiology. We have recently shown that increased ethanol-seeking in a behavioral model of relapse in a rat model of alcoholism was associated with increased oligodendrogenesis which was positively correlated with platelet/endothelial cell adhesion molecule (PECAM-1) expression in the medial prefrontal cortex (mPFC). The current study investigated whether newly born oligodendrocytes form close physical associations with endothelial cells expressing PECAM-1 and whether these changes were accompanied by altered blood-brain barrier (BBB) integrity. ⋯ Furthermore, voluntary wheel running during abstinence enhanced SMI-71 expression in endothelial cells, indicating protection against abstinence-induced reduction in BBB integrity. Taken together, these results suggest that ethanol experience and abstinence disrupts homeostasis in the oligo-vascular niche in the mPFC. Reversing these mechanisms may hold the key to reducing propensity for relapse in individuals with moderate to severe alcohol use disorder.
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Previous studies have shown a close relationship between the serotonin system and working memory (WM), but the neural mechanism for the role of the serotonin system on the WM is unclear. The frontoparietal network is involved in WM and is associated with the serotonin system. ⋯ Moreover, the mean connectivity in the right inferior parietal lobule was positively correlated with WM performance. These brain network analysis findings could provide a new perspective on the neural mechanisms of gene-gene interactions and on individual differences in cognitive functions.
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Alzheimer's disease (AD) is the most prevalent disorder of senile dementia mainly characterized by amyloid-beta peptide (Aβ) deposits in the brain. Cannabinoids are relevant to AD as they exert several beneficial effects in many models of this disease. Still, whether the endocannabinoid system is either up- or down-regulated in AD has not yet been fully elucidated. ⋯ Conversely, a high availability of 2-AG resulting from an increase in DAGL and lysophosphatidic acid phosphohydrolase activities occurred in the presence of Aβ1-40 fibrils although synaptosomal membrane disruption was also observed. Interestingly, neither synaptosomal mitochondrial viability assayed by MTT reduction nor membrane lipid peroxidation assayed by TBARS formation measurements were altered by Aβ1-40 oligomers or fibrils. These results show a differential effect of Aβ1-40 peptide on 2-AG metabolism depending on its conformation.
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The locomotor central pattern generator is a neural network located in the ventral aspect of the caudal spinal cord that underlies stepping in mammals. While many genetically defined interneurons that are thought to comprise this neural network have been identified and characterized, the dI6 cells- which express the transcription factors WT1 and/or DMRT3- are one population that settle in this region, are active during locomotion, whose function is poorly understood. These cells were originally hypothesized to be commissural premotor interneurons, however evidence in support of this is sparse. ⋯ Retrograde tracing experiments indicate that the majority of dI6 cells project descending axons, and some make monosynaptic or disynaptic contacts onto motoneurons on either side of the spinal cord. Analysis of their activity during non-resetting deletions, which occur during bouts of fictive locomotion, suggests that these cells are involved in both locomotor rhythm generation and pattern formation. This study provides a thorough characterization of the dI6 cells labeled in the TgDbx1Cre;R26EFP;Dbx1LacZ transgenic mouse, and supports previous work suggesting that these cells play multiple roles during locomotor activity.