Neuroscience
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There have been extensive studies of intrinsic connectivity networks (ICNs) in the human brains using resting-state functional magnetic resonance imaging (fMRI) in the literature. However, the functional organization of ICNs in macaque brains has been less explored so far, despite growing interests in the field. ⋯ These 70 ICNs are interpreted based on two publicly available parcellation maps of macaque brains and our work significantly expand currently known macaque ICNs already reported in the literature. In general, this set of connectome-scale group-wise consistent ICNs can potentially benefit a variety of studies in the neuroscience and brain-mapping fields, and they provide a foundation to better understand brain evolution in the future.
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In this study, we examined the relationship between tractography-based measures of white matter integrity (ex. fractional anisotropy [FA]) from diffusion tensor imaging (DTI) and five reading-related tasks, including rapid automatized naming (RAN) of letters, digits, and objects, and reading of real words and nonwords. Twenty university students with no reported history of reading difficulties were tested on all five tasks and their performance was correlated with diffusion measures extracted through DTI tractography. A secondary analysis using whole-brain Tract-Based Spatial Statistics (TBSS) was also used to find clusters showing significant negative correlations between reaction time and FA. ⋯ These findings provide evidence for the role of the inferior fronto-occipital fasciculus in tasks that are highly demanding of orthography-phonology translation (e.g., nonword reading) and semantic processing (e.g., RAN object). This demonstrates the importance of the inferior fronto-occipital fasciculus in basic naming and suggests that this tract may be a sensitive predictor of rapid naming performance within the typical population. We discuss the findings in the context of current models of reading and speech production to further characterize the white matter pathways associated with basic reading processes.
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Stress during early development produces lasting effects on psychopathological outcomes. We analysed the impact of prior intermittent, physical stress (IPS) during early adolescence (PD 22-33) on anxiety-like behaviour of female rats in adulthood. After behavioural testing, we used immunohistochemistry for the 5-HT transporter (SERT) to evaluate 5-HT innervation profiles in the medial prefrontal cortex (mPFC) and ventral hippocampus (VH). ⋯ Selective stress-induced increases in the density of SERT-ir positive fibres were found in the infralimbic (IL) subregion of the mPFC but not in the cingulate or prelimbic (PL) subregions. IPS in early adolescence did not affect 5-HT innervation profiles in any sub-fields of the VH. Our findings confirm and extend on earlier evidence that stress during early adolescence promotes the emergence of an anxious phenotype and provide novel evidence that these effects are associated with increased 5-HT innervation of the IL mPFC.
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Deep brain stimulation (DBS) of the medial forebrain bundle (MFB) induces rapid improvement of depressive symptoms in patients suffering from treatment-refractory major depressive disorder (MDD). It has been hypothesized that activation of the dopamine (DA) system contributes to this effect. To investigate whether DBS in the MFB affects DA release in the striatum, we combined DBS with fast-scan cyclic voltammetry (FSCV) in freely moving rats. ⋯ These findings suggest that effects of DBS in the MFB are mediated by an acute change in extracellular DA concentration, but more research is needed to further explore the potentially sustained duration of this effect. Together, our results provide both support and refinement of the hypothesis that MFB DBS activates the DA system: DBS induces an increase in overall ambient concentration of DA, but spontaneous or reward-associated more rapid, phasic DA dynamics are not enhanced. This knowledge improves our understanding of how DBS affects brain function and may help improve future therapies for depressive symptoms.
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The transition from multipotent neural stem cells (NSCs) to terminally differentiated neurons is a multistep process, and the transition is finely regulated by transcription factors with basic helix-loop-helix (bHLH) motifs. Melatonin is an endogenous neurohormone with profound neurotrophic and neuroprotective effects both during the embryonic developmental stage and adulthood. The effects of melatonin on the differentiation of NSCs have been reported, and these effects may be responsible for its neuroprotective properties. ⋯ Increased H3K14 acetylation altered the chromatin state of the promoters of bHLH factors Neurogenin1 and NeuroD1 and activated their transcription; then, Neurogenin1 and NeuroD1 initiated and sustained the commitment to neuronal fates. As we know, CBP/p300 is an important class of histone acetyltransferases that acetylate histone H3K14, we found that melatonin activated the histone acetyltransferase activity of CREB-binding protein (CBP)/p300 via ERK signaling pathways. For the first time, we systematically showed the molecular mechanism of action of melatonin, which suggested that melatonin functions as a regulator of the acetylation-dependent gene expression network.