Neuroscience
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Dyslexia is an impairment of reading and spelling that affects both children and adults even after many years of schooling. Dyslexic readers have deficits in the integration of auditory and visual inputs but the neural mechanisms of the deficits are still unclear. This fMRI study examined the neural processing of auditorily presented German numbers 0-9 and videos of lip movements of a German native speaker voicing numbers 0-9 in unimodal (auditory or visual) and bimodal (always congruent) conditions in dyslexic readers and their matched fluent readers. ⋯ Importantly, such an enhancement effect was absent in dyslexic readers. Moreover, the auditory network (bilateral superior temporal regions plus medial PFC) was dynamically modulated during audiovisual integration in fluent, but not in dyslexic readers. These results suggest that superior temporal dysfunction may underly poor audiovisual speech integration in readers with dyslexia.
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G-protein-coupled receptors (GPCRs) are shown to be involved in Alzheimer's disease (AD) pathogenesis. However, because GPCRs include a large family of membrane receptors, it is unclear which specific GPCR or pathway with rational ligands can become effective therapeutic targets for AD. ⋯ Because amylin shares a similar secondary structure with amyloid-β peptide (Aβ), I propose that the AmR/GPCR pathway is disturbed by a large amount of Aβ in the AD brain, leading to tau phosphorylation, neuroinflammation and neuronal death in the pathological cascade. Amylin-type peptides, readily crossing the blood-brain barrier (BBB), are the rational ligands to enhance this GPCR pathway and may exhibit utility as novel therapeutic agents for treating AD.
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During the last few years, rich-club (RC) organization has been studied as a possible brain-connectivity organization model for large-scale brain networks. At the same time, empirical and simulated data of neurophysiological models have demonstrated the significant role of intra-frequency and inter-frequency coupling among distinct brain areas. The current study investigates further the importance of these couplings using recordings of resting-state magnetoencephalographic activity obtained from 30 mild traumatic brain injury (mTBI) subjects and 50 healthy controls. ⋯ Additionally, mTBI and control subjects can be correctly classified with high accuracy (98.6%), whereas a general linear regression model can effectively predict the subject group using the ratio of type I and type II coupling in the (δ, θ), (δ, β), (δ, γ1), and (δ, γ2) frequency pairs. These findings support the presence of an RC organization simultaneously with dominant frequency interactions within a single functional graph. Our results demonstrate a hyperactivation of intrinsic RC networks in mTBI subjects compared to controls, which can be seen as a plausible compensatory mechanism for alternative frequency-dependent routes of information flow in mTBI subjects.
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Carvacrol is a monoterpene that has been linked to neuroprotection in several animal models of neurodegeneration, including ischemia, epilepsy and traumatic neuronal injury. In this study, we investigated the effects of carvacrol (i.p.) upon the neurodegeneration induced by 6-hydroxy-dopamine unilateral intrastriatal injections in mice. We have also used the cylinder test to assess the behavioral effects of carvacrol in that model of Parkinson's disease, and immunoblots to evaluate the levels of caspase-3 and TRPM7, one of major targets of carvacrol. ⋯ Caspase-3 levels were very high after toxin injections, but carvacrol appeared to reduce them to control levels. Finally, TRPM7, observed by immunoblots, increased after 6-hydroxy-dopamine, suggesting the involvement of this cation channel in the ensuing neurodegenerative process. The present data suggest that carvacrol promotes a marked neuroprotection in the 6-hydroxy-dopamine model of Parkinson's disease, possibly by its non-specific blocking effect upon TRPM7 channels.
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Goal-oriented arm movements are characterized by a balance between speed and accuracy. The relation between speed and accuracy has been formalized by Fitts' law and predicts a linear increase in movement duration with task constraints. Up to now this relation has been investigated on a short-time scale only, that is during a single experimental session, although chronobiological studies report that the motor system is shaped by circadian rhythms. ⋯ While Fitts' law was held for the whole sessions of the day, the slope of the relation between movement duration and task difficulty expressed a clear modulation, with the lowest values in the afternoon. This variation of the speed-accuracy trade-off in executed and mental movements suggests that, beyond execution parameters, motor planning mechanisms are modulated during the day. Daily update of forward models is discussed as a potential mechanism.