Paired-Associative Stimulation-Induced Long-term Potentiation-Like Motor Cortex Plasticity in Healthy Adolescents

ObjectiveThe objective of this study was to evaluate the feasibility of using paired-associative stimulation (PAS) to study excitatory and inhibitory plasticity in adolescents while examining variables that may moderate plasticity (such as sex and environment).MethodsWe recruited 34 healthy adolescents (aged 13–19, 13 males, 21 females). To evaluate excitatory plasticity, we compared mean motor-evoked potentials (MEPs) elicited by single-pulse transcranial magnetic stimulation (TMS) before and after PAS at 0, 15, and 30 min. To evaluate inhibitory plasticity, we evaluated the cortical silent period (CSP) elicited by single-pulse TMS in the contracted hand before and after PAS at 0, 15, and 30 min.ResultsAll participants completed PAS procedures. No adverse events occurred. PAS was well tolerated. PAS-induced significant increases in the ratio of post-PAS MEP to pre-PAS MEP amplitudes (p < 0.01) at all post-PAS intervals. Neither socioeconomic status nor sex was associated with post-PAS MEP changes. PAS induced significant CSP lengthening in males but not females.ConclusionPAS is a feasible, safe, and well-tolerated index of adolescent motor cortical plasticity. Gender may influence PAS-induced changes in cortical inhibition. PAS is safe and well tolerated by healthy adolescents and may be a novel tool with which to study adolescent neuroplasticity

Infrared plasmons propagate through a hyperbolic nodal metal

Metals are canonical plasmonic media at infrared and optical wavelengths, allowing one to guide and manipulate light at the nanoscale. A special form of optical waveguiding is afforded by highly anisotropic crystals revealing the opposite signs of the dielectric functions along orthogonal directions. These media are classified as hyperbolic and include crystalline insulators, semiconductors, and artificial metamaterials. Layered anisotropic metals are also anticipated to support hyperbolic waveguiding. However, this behavior remains elusive, primarily because interband losses arrest the propagation of infrared modes. Here, we report on the observation of propagating hyperbolic waves in a prototypical layered nodal-line semimetal ZrSiSe. The observed waveguiding originates from polaritonic hybridization between near-infrared light and nodal-line plasmons. Unique nodal electronic structures simultaneously suppress interband loss and boost the plasmonic response, ultimately enabling the propagation of infrared modes through the bulk of the crystal

Modelling human choices: MADeM and decision‑making

Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)

Deep Brain Stimulation Suppresses Gamma Oscillations in Treatment Resistant Depression

Background: Major depressive disorder is a debilitating psychiatric condition with high rates of treatment resistance that may be associated with working memory (WM) deficits. For treatment resistant depression (TRD) patients, deep brain stimulation (DBS) is emerging as an effective therapeutic option. Objective: To determine if electroencephalography signals recorded during DBS ON and OFF states while performing WM tasks can serve as biomarkers of therapeutic efficacy for DBS in TRD patients. Results: DBS stimulation suppressed frontal gamma oscillations (30–50Hz) during the ON state relative to the OFF state, an effect that was more pronounced with higher WM load. This suppression strongly correlated with depressive symptoms reduction. Conclusion: Suppression of gamma oscillations by DBS is likely mediated by indirect activation of inhibitory circuits in the frontal cortex. It represents a potential treatment biomarker for DBS in TRD and may lead to more tailored treatment parameters that can result in enhanced efficacy.MAS

Neurobiological Mechanism and Treatment Targets of Magnetic Seizure Therapy for Resolution of Suicidal Ideation in Treatment-Resistant Depression

Background: Major depressive disorder affects 16% of the general population and is associated with increased risk of suicidal ideation. Up to 40% depression patients do not respond to two or more antidepressant trials and are referred to as having treatment-resistant depression (TRD). Magnetic Seizure Therapy (MST) is a promising intervention for TRD patients and may be effective at targeting their suicidal ideation. Methods: To better understand the mechanism of MST and to identify potential biomarkers, TRD patients were recruited from an open label MST trial and assessed before and after the treatment course with measures of transcranial magnetic stimulation and electroencephalography (TMS-EEG) in the dorsolateral prefrontal cortex (DLPFC). Objectives/Hypotheses: 1) To evaluate if higher GABAergic inhibition (measure: N100 peak and long-interval cortical inhibition (LICI)) at baseline is effective at predicting suicidal ideation resolution (SI-resolution) after MST; 2) To determine if MST produces neuroplasticity (measure: cortical evoked activity) while decreasing GABAergic inhibition (measure: LICI); 3) To check if MST works by decreasing the strength of the DLPFC to subgenual cingulate (SGC) connection (measure: significant current scatter). Results: 1) Higher prefrontal GABAergic inhibition at baseline predicted SI-resolution after MST with 89% accuracy. 2) MST produced neuroplasticity in tandem with individual specific reductions in GABAergic inhibition that are indicative of SI-resolution after treatment. 3) Stronger DLPFC to SGC connection at baseline was able to predict SI-resolution with 83% accuracy, while the connectivity was significantly decreased after the treatment course. Conclusion: MST works by producing neuroplasticity in TRD patients with individual variations in suicidal ideation reduction governed by differences in GABAergic inhibition, both at baseline and in the process of treatment. The neuroplasticity produced by MST involved a neural circuit component part of the limbic-cortical network, specifically the DLPFC to SGC connection, which determined the efficacy of MST at baseline and is modified by the seizure treatments.Ph.D.2019-12-19 00:00:0

Comparative evaluation of autosomal STRs and X-chromosome STRs as a complement of autosomal STRs in kinship testing in Southern Han Chinese

Nowadays, kinship testing is very common in forensic caseworks, but the power of autosomal short tandem repeats (A-STRs) may be limited in complex cases. X-Chromosome short tandem repeats (X-STRs), having a unique heritage mode, should be of special use in some deficient cases. To evaluate and compare the potential of A-STR and X-STR as supplement genetic markers in deficient kinship testing, we simulated 10,000 duos for each of 18 kinds of relationships involving full sibling, half-sibling, grandparent-grandchild, and uncle/aunt-nephew/niece. Loci from STRTyper10, PowerPlex 16, and Investigator Argus X-12 were studied in Southern Han Chinese and the distribution of likelihood ratio (LR) values was analysed. With the addition of the X-12 system, the distribution of LR values for the full sisters, paternal half-sisters, paternal grandmother-granddaughters, maternal aunt-nieces, and maternal aunt-nephews separated much more obviously from those of unrelated duos, and the effectiveness was 1.0000, 0.99865, 0.9991, 0.8996 and 0.9634, respectively, which was more efficient than A-STRs. For the individual duos with other relationships, the effects of adding X-STRs and A-STRs were similar. Therefore, for the Southern Han Chinese, X-STRs can be very useful in kinship testing involving full sisters, paternal half-sisters, paternal grandmother-granddaughters, and maternal aunt-nieces/nephews

Neurophysiological Characterization of Attentional Performance Dysfunction in Schizophrenia Patients in a Reverse-Translated Task.

Attentional dysfunction in schizophrenia (SZ) contributes to the functional deficits ubiquitous to the disorder. Identifying the neural substrates of translational measures of attentional dysfunction would prove invaluable for developing therapeutics. Attentional performance is typically assessed via continuous performance tasks (CPTs), though many place additional cognitive demands with little cross-species test-relevance. Herein, event-related potentials (ERPs) were used to investigate the neurophysiological correlates of attention and response inhibition of SZ and healthy participants, whereas they performed the cross-species-translated five-choice CPT (5C-CPT). Chronically ill, medicated SZ patients and matched controls (n=25 SZ and 26 controls) were tested in the 5C-CPT, in conjunction with ERP and source localization assessments. The ERPs generated in response to correctly identified target and non-target trials revealed three peaks for analysis, corresponding to sensory registration (P1), response selection (N2), and response action (P3). Behavioral responses revealed that SZ patients exhibited impaired attention driven by impaired and slower target detection, and poorer cognitive control. ERPs revealed decreased N2 amplitudes reflecting poorer response selection for both target and non-target trials, plus reduced non-target P3s in SZ patients, the latter accounting for 37% of variance in negative symptoms. Source analyses revealed that the brain regions of significant differences localized to the left dorsolateral prefrontal cortex during response selection and the posterior cingulate cortex for cognitive processes. SZ patients exhibited impaired attention and cognitive control, characterized by less robust frontal and parietal ERP distributions across the response selection and cognitive response time windows, providing neurophysiological characterization of attentional dysfunction in SZ using the reverse-translated 5C-CPT

Electronic correlations in nodal-line semimetals

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