Neuroscience
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Little is known about how proprioceptive signals arising from muscles reach to higher brain regions such as the cerebral cortex. We have recently shown that a particular thalamic region, the caudo-ventromedial edge (VPMcvm) of ventral posteromedial thalamic nucleus (VPM), receives the proprioceptive signals from jaw-closing muscle spindles (JCMSs) in rats. In this study, we further addressed how the orofacial thalamic inputs from the JCMSs were transmitted from the thalamus (VPMcvm) to the cerebral cortex in rats. ⋯ In contrast, WGA-HRP injections into the lingual nerve area of core VPM demonstrated that axon terminals were mainly labeled in the core regions of the primary and secondary somatosensory cortices, which were far from the dGIrvs2. These results suggest that the dGIrvs2 is a specialized cortical region receiving the orofacial proprioceptive inputs. Functional contribution of the revealed JCMSs-VPMcvm-dGIrvs2 pathway to Tourette syndrome is also discussed.
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Parkinson's disease is a debilitating neurodegenerative movement disorder, characterized by the progressive and selective loss of dopaminergic neurons located in the substantia nigra, leading to clinical motor symptoms. The factors involved in PD are rather multifaceted. There are many cellular pathways contributing to its neuro-pathogenesis, which include abnormal protein aggregation, impaired ubiquitin proteasome system, autophagy, and neuroinflammation. ⋯ Since they somewhat modulate many mRNA targets simultaneously, many cellular pathways may be affected by one individual miRNA. Moreover, miRNAs can stably circulate in cerebrospinal fluid and blood, and their expression pattern can reflect the molecular pathophysiology, thus making them promising biomarkers in PD diagnosis and prognosis. In this review, we will review the recent progress on miRNA's mechanism in PD pathogenesis and discuss the possibilities of miRNAs as PD molecular biomarkers.
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The capacity to identify unanticipated abnormal cues in a natural scene is vital for animal survival. Stimulus-specific adaptation (SSA) has been considered the neuronal correlate for deviance detection. There have been comprehensive assessments of SSA in the frequency domain along the ascending auditory pathway, but only little attention given to deviance detection in the spatial domain. ⋯ The variability in neuronal spatial discriminability among the TRN population was directly related to response difference (RD) but not variance; meanwhile, further analyses attributed higher spatial sensitivity at deviant locations to larger RD. Astonishingly, a significant correlation was found between the amount of adaptation and deviant discriminability. Collectively, our results suggest that adaptation facilitates rare location discrimination by sharpening the response gap between two locations.
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Several diseases are characterized by cognitive instability, which is amplified in the conditions of sleep deprivation (SD). Cognitive instability in SD can be examined by the number of lapses on the psychomotor vigilance test (PVT), which is considered to be a gold standard in the field. However, the number of PVT lapses widely range according to inter-individual differences, from apparent cognitive resistance to severe cognitive impairment. ⋯ Our results showed significant negative correlations between numbers of PVT lapses and FA in multiple WM tracts, with the FA variations in the superior longitudinal fasciculus and splenium of the corpus callosum accounting for nearly 37.5% of individual variability in PVT lapses. In addition, dichotomized analyses indicated that the resilient participants exhibited significantly higher FA values compared with the vulnerable participants. Together, these findings suggest that cognitive instability after SD was closely associated with individual differences in WM integrity.
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To explore brain activity and the related neurochemical processes, current research focuses increasingly on the combined acquisition of 1H MR spectra and fMRI data to investigate potential associations between local metabolite resting state levels and stimulus-induced BOLD signal changes. In this study, whole-brain fMRI measurements and localized functional 1H MEGA-PRESS MRS scans were conducted at 3T in healthy subjects prior to and during acute pain stimulation to quantify resting state GABA+/tCr and Glx/tCr levels in the insular cortex together with their stimulus-induced changes and to explore associations between these neurochemical parameters with intra-regional but also inter-regional BOLD responses. Inter-regionally, a significant negative correlation between the BOLD signal of a cluster in the supplementary motor area with overlap to the mid-cingulate cortex (R = -0.56, p = 0.004) and the insular resting state GABA+/tCr was obtained. ⋯ No intra-regional association was observed between BOLD and metabolite measures. These findings point toward interactions between metabolite levels and stimulus-induced BOLD responses in brain regions belonging to the pain processing network. The combination of fMRS and fMRI provides a powerful tool to improve our understanding about the complex system of neurochemical processes and brain activity within brain networks.