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Background Transcranial Alternating Current Stimulation (tACS) consists in delivering electric current to the brain using an oscillatory pattern that may entrain the rhythmic activity of cortical neurons. When delivered at gamma frequency, tACS modulates motor performance and GABA-A-ergic interneuron activity. Objective Since interneuronal discharges play a crucial role in brain plasticity phenomena, here we co-stimulated the primary motor cortex (M1) in healthy subjects by means of tACS during intermittent theta-burst stimulation (iTBS), a transcranial magnetic stimulation paradigm known to induce long-term potentiation (LTP)-like plasticity. Methods We measured and compared motor evoked potentials before and after gamma, beta and sham tACS-iTBS. While we delivered gamma-tACS, we also measured short-interval intracortical inhibition (SICI) to detect any changes in GABA-A-ergic neurotransmission. Results Gamma, but not beta and sham tACS, significantly boosted and prolonged the iTBS-induced after-effects. Interestingly, the extent of the gamma tACS-iTBS after-effects correlated directly with SICI changes. Conclusions Overall, our findings point to a link between gamma oscillations, interneuronal GABA-A-ergic activity and LTP-like plasticity in the human M1. Gamma tACS-iTBS co-stimulation might represent a new strategy to enhance and prolong responses to plasticity-inducing protocols, thereby lending itself to future applications in the neurorehabilitation setting. [ABSTRACT FROM AUTHOR]

Objective: It is inconclusive as to whether benzodiazepines (BZDs) are related to cognitive deterioration in the elderly populations. Animal studies suggest that γ-aminobutyric acid A receptor agonists, such as BZDs, may prevent Aβ-neurotoxicity and reduce β-amyloid (Aβ). However, no studies have investigated the effects of BZD use on Aβ in humans.Methods: This cross-sectional, prospective study using Alzheimer's Disease Neuroimaging Initiative sites in the United States and Canada on nondemented elderly adults between 55 and 90 years of age assessed cortical Aβ levels by positron emission tomography radiotracer F18-Florbetapir. Changes in global cognitive function and verbal memory performance over 2 years were assessed using scores on Montreal Cognitive Assessment and five domains of Rey Auditory Verbal Learning Test, respectively.Results: Previous BZD users (N = 15) had lower cortical Aβ levels in frontal (F(1, 26) = 8.82, p = 0.006), cingulate (F(1, 26) = 8.58, p = 0.007), parietal (F(1, 26) = 7.31, p = 0.012), and temporal (F(1, 26) = 7.67, p = 0.010) regions compared with matched BZD nonusers (N = 15), after controlling for history of psychiatric disorders and antidepressant use. Also, no differences were found in global cognitive function and changes in cortical Aβ over 2 years between continuous BZD users (N = 15) andthe matched nonuser group (N = 15).Conclusion: Previous BZD use was associated with lower cortical Aβ levels in nondemented elderly control subjects. Future studies with larger samples are required to replicate our findings. [ABSTRACT FROM AUTHOR]

Abstract: This study is the first one to construct the reliable structure of the α1/γ2 interface of Gamma aminobutyric acid type A (GABA-A) receptor by homology modeling and refined every loop of the whole protein structure. The modeling GABA-A receptor was validated by docking the control compounds in binding site, checking the key residue in α1/γ2 interface, probability density function (PDF) value, and Ramachandran plot. This paper is also the first one to propose that jujubogenin is the effective component in suanzaoren decoction, neither jujuboside A nor jujuboside B by chemoinformatics and pharmacoinformatics approach. In addition, pharmacophore analysis showed that the oxygens on jujubogenin approached α1-TYR160 and γ2-LYS184, respectively. The comparative molecular field analysis (CoMFA) model yielded a value of 0.731 and an r 2 of 0.942 at 5 components. Comparative molecular similarity indices analysis (CoMSIA) produced a of 0.617 and an r 2 of 0.921 at 5 components. The CoMFA and CoMSIA models showed statistically significant results. Hence, based on the results of docking, ADMET descriptor, pharmacophore, and three-dimensional quantitative structure–activity relationship (3D-QSAR) studies, the jujubogenin was suggested to be the effective GABA-A agonist in suanzaoren decoction. [Copyright &y& Elsevier]