Neuroscience
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Adolescence is a period during which the medial prefrontal cortex (mPFC) undergoes significant remodeling. The netrin-1 receptor, deleted in colorectal cancer (DCC), controls the extent and organization of mPFC dopamine connectivity during adolescence and in turn directs mPFC functional and structural maturation. Dcc haploinsufficiency leads to increased mPFC dopamine input, which causes improved cognitive processing and resilience to behavioral effects of stimulant drugs of abuse. ⋯ Notably, neither group shows the typical pattern of mPFC dopamine receptor pruning in adolescence, but adult haploinsufficient mice show increased D2 receptor density in the mPFC. These results show that DCC receptors contribute to the dynamic refinement of D1 and D2 receptor expression in striatal regions across adolescence. The age-dependent expression of dopamine receptor in C57BL6 mice shows marked differences from previous characterizations in rats.
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To categorize the perceived objects, brain utilizes a broad set of its resources and encoding strategies. Yet, it remains elusive how the category information is encoded in the brain. While many classical studies have sought the category information in the across-trial-averaged activity of neurons/neural populations, several recent studies have observed category information also in the within-trial correlated variability of activities between neural populations (i.e. dependent variability). ⋯ The inter-channel dependent variability showed an ignorable effect on the encoding. We also investigated the role of those factors in the encoding of variations which showed similar effects. These results imply that the brain, rather than variability, seems to use the average activity to convey information on the category of the perceived objects.
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Inhalation of carbon dioxide (CO2) is frequently employed as a biological challenge to evoke intense fear and anxiety. In individuals with panic disorder, CO2 reliably evokes panic attacks. Sensitivity to CO2 is highly heterogeneous among individuals, and although a genetic component is implicated, underlying mechanisms are not clear. ⋯ Conversely, DβH-positive cell counts within the LC were significantly higher in CO2-sensitive strains. Collectively, our data provide evidence for strain dependent, differential CO2-sensitivity and potential differences in monoaminergic systems regulating panic and anxiety. Comparative studies between CO2-vulnerable and resistant strains may facilitate the mechanistic understanding of differential CO2-sensitivity in the development of panic and anxiety disorders.
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Multiple sclerosis (MS) patients are three to six times more likely to develop epilepsy compared to the rest of the population. Seizures are more common in patients with early onset or progressive forms of the disease and prognosticate rapid progression to disability and death. ⋯ Immunohistochemical (IHC) analyses within the hippocampal CA1 region revealed extensive demyelination, loss of parvalbumin (PV+) interneurons, widespread gliosis, and changes in aquaporin-4 (AQP4) expression. Our results suggest that chronically demyelinated mice are a valuable model with which we may begin to understand the mechanisms underlying demyelination-induced seizures.
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The somatostatin 4 receptor (sst4) is widely expressed in stress-related brain areas (e.g. hippocampus, amygdala) and regulates the emotional behavior in acute situations. Since its importance in chronic stress-induced complex pathophysiological alterations is unknown, we investigated the involvement of sst4 in the responsiveness to chronic variable stress (CVS). Sstr4 gene-deficient (Sstr4-/-) mice and their wildtype counterparts (Sstr4+/+) were used to examine the behavioral and neuroendocrine alterations as well as chronic neuronal activity (FosB expression) changes in response to CVS. ⋯ Basal plasma corticosterone concentrations did not change after the CVS in either genotype. FosB immunopositivity in the central and basolateral amygdaloid nuclei was enhanced in stressed knockouts, but not in wild types. This is the first evidence that sst4 activation is involved in the behavioral and neuroendocrine alterations induced by chronic stress with a crucial role of plastic changes in the amygdala.