Neuroscience
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Previous studies have found that native Chinese speakers recruit the bilateral fusiform gyrus to read English words, in the same manner as they read Chinese words (i.e., the assimilation process). In this study, we quantified the neural pattern similarity between native (L1) and second languages (L2) by using representational similarity analysis (RSA), and examined the modulatory effects of L2 proficiency on cross-language neural pattern similarity (PS) in the bilateral fusiform cortex. Results showed that, for Chinese-English bilinguals, higher reading proficiency in L2 was associated with greater cross-language PS in the left fusiform gyrus, but with lower PS in the right fusiform gyrus. These results suggest that, as L2 proficiency increases, the assimilation process is enhanced in the region for word reading (left fusiform gyrus), but reduced in the region for nonlinguistic processing (right fusiform gyrus).
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We examined how motor responses to a stimulus evolve as individuals learn to predict when a stimulus will appear, by comparing responses to a regular versus irregular stimulus train. The study was conducted with two groups of adults - one responded to the regular appearance of a visual stimulus every 3 s (R group) and the second responded to the irregular presentation of the same stimulus (IR group) at intervals varying between 2 and 4 s. Participants responded to the appearance of the stimulus by bending over to press a button that was slightly out of reach. ⋯ Soleus muscle deactivation is an indicator of movement preparation. EMG integrals for this muscle a little before stimulus onset showed a trend for greater decrease in the R group. In summary, our study shows that temporal expectations over repeated stimulus presentation permit the dynamic optimization of motor activity with progressively faster response times, muscle activation onset times and lower muscle activation amplitudes.
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Comparative Study
Comparison of Actions between L-DOPA and Different Dopamine Agonists in Striatal DA-Depleted Microcircuits In Vitro: Pre-Clinical Insights.
Parkinson's disease (PD) is a neurodegenerative illness presenting motor and non-motor symptoms due to the loss of dopaminergic terminals in basal ganglia, most importantly, the striatum. L-DOPA relieves many motor signs. Unfortunately, in the long term, L-DOPA use causes motor disabilities by itself and does not act in comorbid conditions such as depression. ⋯ All DA-agonists tend to maintain ensemble alternation seen in control circuits after CtxS. However, quantitative analyses suggest differences in their actions: in general, DA-agonists only approximate L-DOPA actions. Nonetheless no treatment, including L-DOPA, completely restores microcircuit dynamics to control conditions.
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Response inhibition is a central aspect of cognitive control. Usually, response inhibition is examined using information from a single sensory modality. Yet, evidence suggests that conflicts between information from different modalities affect response inhibition. ⋯ This also explains why less intense braking processes (reflected by IFG activity) are still able to maintain a reasonable response inhibition performance level. It can be concluded that the tactile and visual domains do not only differ in regard to their efficiency to trigger response inhibition processes but also in their susceptibility to interference while informing inhibitory control. Clinical implications are discussed.
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Acute cutaneous exposure to allergen often leads to itch, but seldom pain. The effect of mast cell activation on cutaneous C-fibers was studied using innervated isolated mouse skin preparation that allows for intra-arterial delivery of chemicals to the nerve terminals in the skin. Allergen (ovalbumin) injection into the isolated skin of actively sensitized mice strongly stimulated chloroquine (CQ)-sensitive C-fibers (also referred to as "itch" nerves); on the other hand, CQ-insensitive C-fibers were activated only modestly, if at all. ⋯ Ovalbumin also strongly activated itch C-fibers in skin isolated from Mrgpr-cluster Δ-/- mice. When pyrilamine was studied in the Mrgpr-cluster Δ-/- mice thereby eliminating the influence of both histamine H1 and Mrgpr receptors (MrgprA3 and C11 are selectively expressed by itch nerves), the ovalbumin response was very nearly eliminated. The data indicate that the acute activation of itch C-fibers in mouse skin is largely secondary to the combined effect of activation of histamine H1 and Mrpgr receptors.