Neuroscience
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Mindfulness is typically defined as nonjudgmental awareness of experiences in the present moment, which is beneficial for mental and physical well-being. Previous studies have identified multiple regions in the default mode network (DMN) that are involved in mindfulness, but little is known about how these regions work collaboratively as a network. ⋯ Post-hoc analyses of these two nodes further revealed that graph-based nodal properties of the thalamus, not the PCC, were negatively correlated with trait mindfulness, suggesting that a low involvement of the thalamus in the DMN is relevant for high trait mindfulness. Our findings not only suggest the thalamus as a switch between mind-wandering and mindfulness, but also invite future studies on mechanisms of how mindfulness produces beneficial effects by modulating the thalamus.
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Reaction time (RT), a widely used measure of human performance in experimental psychology, has recently been included as a regressor of interest in functional magnetic resonance imaging (fMRI) data analysis. Few studies reported RT-related brain regions, but the nature of this activity is not fully understood. We aimed at exploring this topic by implementing a simple saccadic task which evokes fast and homogeneous reactions that require only the basic neural processes. ⋯ The results provide evidence that even a small difference in RTs can be linked with significant increase of HDR in task-related areas. Moreover, this increase is not linear, but rather quadratic. Our findings highlight the importance of controlling for RT in fMRI data analysis when contrasting conditions that vary in RT to avoid the misinterpretation of results.
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Single-cell injection with lipophilic dyes following immunocytochemistry is extremely valuable for revealing the morphology of a cell expressing a protein of interest, and is a more reliable technique for cell type classification than standard morphological techniques. This study focuses on calretinin (CR), which is used as a selective marker for distinct subpopulations of neurons in the rabbit retina. The present study used single-cell injection after immunocytochemistry to describe the density and types of CR-containing retinal ganglion cells (RGCs) in rabbit. ⋯ Our results show that 10 morphologically different types of rabbit RGCs expressed CR. CR-containing RGCs were heterogeneous in their morphology. This approach to integrate the selective expression of a particular protein with spatial patterns of dendritic arborization will lead to a better understanding of RGCs.
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Intraneuronal accumulation of beta-amyloid protein (Aβ) is an early pathological change in Alzheimer's disease (AD). Recent studies demonstrate that α7 nicotinic acetylcholine receptor (α7nAChR) binds to soluble Aβ with a high affinity. In vitro and in vivo experiments also show that Aβ activates p38 MAPK and ERK1/2 signaling pathways via the α7nAChR. ⋯ Our data demonstrate that Aβ1-42 induces an α7nAChR-dependent pathway that relates to the activation of p38 MAPK and ERK1/2, resulting in internalization of Aβ1-42. Our findings suggest that α7nAChR and MAPK signaling pathways play an important role in the uptake and accumulation of Aβ1-42 in SH-SY5Y cells. Blockade of α7nAChR may have a beneficial effect by limiting intracellular accumulation of amyloid in AD brain and serves a potential therapeutic target for AD.
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Auditory brainstem networks facilitate sound source localization through binaural integration. A key component of this circuitry is the projection from the ventral cochlear nucleus (VCN) to the medial nucleus of the trapezoid body (MNTB), a relay nucleus that provides inhibition to the superior olivary complex. This strictly contralateral projection terminates in the large calyx of Held synapse. ⋯ We then determined the distribution of glial cells following early (P2) unilateral cochlear removal, which results in formation of ectopic projections from the intact VCN to ipsilateral MNTB. We found that following perturbation, astrocytic markers showed expression near the ectopic ipsilateral calyx. Taken together, the developmental expression patterns are consistent with a role for glial cells in the maturation of the calyx of Held and suggest that these cells may have a similar role in maturation of lesion-induced connections.