Nonlinear dynamics underlying sensory processing dysfunction in schizophrenia.

Natural systems, including the brain, often seem chaotic, since they are typically driven by complex nonlinear dynamical processes. Disruption in the fluid coordination of multiple brain regions contributes to impairments in information processing and the constellation of symptoms observed in neuropsychiatric disorders. Schizophrenia (SZ), one of the most debilitating mental illnesses, is thought to arise, in part, from such a network dysfunction, leading to impaired auditory information processing as well as cognitive and psychosocial deficits. Current approaches to neurophysiologic biomarker analyses predominantly rely on linear methods and may, therefore, fail to capture the wealth of information contained in whole EEG signals, including nonlinear dynamics. In this study, delay differential analysis (DDA), a nonlinear method based on embedding theory from theoretical physics, was applied to EEG recordings from 877 SZ patients and 753 nonpsychiatric comparison subjects (NCSs) who underwent mismatch negativity (MMN) testing via their participation in the Consortium on the Genetics of Schizophrenia (COGS-2) study. DDA revealed significant nonlinear dynamical architecture related to auditory information processing in both groups. Importantly, significant DDA changes preceded those observed with traditional linear methods. Marked abnormalities in both linear and nonlinear features were detected in SZ patients. These results illustrate the benefits of nonlinear analysis of brain signals and underscore the need for future studies to investigate the relationship between DDA features and pathophysiology of information processing.

Direct versus indirect revascularization procedures for moyamoya disease: a comparative effectiveness study.

OBJECTIVE Moyamoya disease (MMD) is a chronic cerebrovascular disease that can lead to devastating neurological outcomes. Surgical intervention is the definitive treatment, with direct, indirect, and combined revascularization procedures currently employed by surgeons. The optimal surgical approach, however, remains unclear. In this decision analysis, the authors compared the effectiveness of revascularization procedures in both adult and pediatric patients with MMD. METHODS A comprehensive literature search was performed for studies of MMD. Using complication and success rates from the literature, the authors constructed a decision analysis model for treatment using a direct and indirect revascularization technique. Utility values for the various outcomes and complications were extracted from the literature examining preferences in similar clinical conditions. Sensitivity analysis was performed. RESULTS A structured literature search yielded 33 studies involving 4197 cases. Cases were divided into adult and pediatric populations. These were further subdivided into 3 different treatment groups: indirect, direct, and combined revascularization procedures. In the pediatric population at 5- and 10-year follow-up, there was no significant difference between indirect and combination procedures, but both were superior to direct revascularization. In adults at 4-year follow-up, indirect was superior to direct revascularization. CONCLUSIONS In the absence of factors that dictate a specific approach, the present decision analysis suggests that direct revascularization procedures are inferior in terms of quality-adjusted life years in both adults at 4 years and children at 5 and 10 years postoperatively, respectively. These findings were statistically significant (p < 0.001 in all cases), suggesting that indirect and combination procedures may offer optimal results at long-term follow-up.

Pierre Curie: the anonymous neurosurgical contributor.

Pierre Curie, best known as a Nobel Laureate in Physics for his co-contributions to the field of radioactivity alongside research partner and wife Marie Curie, died suddenly in 1906 from a street accident in Paris. Tragically, his skull was crushed under the wheel of a horse-drawn carriage. This article attempts to honor the life and achievements of Pierre Curie, whose trailblazing work in radioactivity and piezoelectricity set into motion a wide range of technological developments that have culminated in the advent of numerous techniques used in neurological surgery today. These innovations include brachytherapy, Gamma Knife radiosurgery, focused ultrasound, and haptic feedback in robotic surgery.

Automated quantification of neuronal networks and single-cell calcium dynamics using calcium imaging.

BACKGROUND: Recent advances in genetically engineered calcium and membrane potential indicators provide the potential to estimate the activation dynamics of individual neurons within larger, mesoscale networks (100s-1000+neurons). However, a fully integrated automated workflow for the analysis and visualization of neural microcircuits from high speed fluorescence imaging data is lacking. NEW METHOD: Here we introduce FluoroSNNAP, Fluorescence Single Neuron and Network Analysis Package. FluoroSNNAP is an open-source, interactive software developed in MATLAB for automated quantification of numerous biologically relevant features of both the calcium dynamics of single-cells and network activity patterns. FluoroSNNAP integrates and improves upon existing tools for spike detection, synchronization analysis, and inference of functional connectivity, making it most useful to experimentalists with little or no programming knowledge. RESULTS: We apply FluoroSNNAP to characterize the activity patterns of neuronal microcircuits undergoing developmental maturation in vitro. Separately, we highlight the utility of single-cell analysis for phenotyping a mixed population of neurons expressing a human mutant variant of the microtubule associated protein tau and wild-type tau. COMPARISON WITH EXISTING METHOD(S): We show the performance of semi-automated cell segmentation using spatiotemporal independent component analysis and significant improvement in detecting calcium transients using a template-based algorithm in comparison to peak-based or wavelet-based detection methods. Our software further enables automated analysis of microcircuits, which is an improvement over existing methods. CONCLUSIONS: We expect the dissemination of this software will facilitate a comprehensive analysis of neuronal networks, promoting the rapid interrogation of circuits in health and disease.

Population structure of two beetle-associated yeasts: comparison of a New World asexual and an endemic Nearctic sexual species in the Metschnikowia clade.

The genetic structure of two related yeast species, one sexual and one asexual, was compared using polymorphic DNA markers. Although both yeasts propagate by asexual budding of haploid cells, Metschnikowia borealis reproduces sexually when compatible strains come in contact. To what extent this has occurred in nature was not known. As Candida ipomoeae is a closely related, asexual species, the two yeasts provide an excellent model system to assess the role of sexual reproduction in a biogeographic context. Natural isolates of the two species were characterized using several polymorphic DNA markers. As predicted for an organism whose reproduction is strictly clonal, C. ipomoeae exhibited low haplotype diversity, high linkage disequilibrium, and high population differentiation. In contrast, M. borealis had unique haplotypes in most isolates, lower population differentiation, and little linkage disequilibrium, demonstrating that sexual recombination is prevalent. Geographic gradients were identified in both species, indicating that historical and climatic factors both play a role in shaping the populations. The spatial structure is also thought to be influenced by the ecology of the small floricolous beetles (family Nitidulidae) that vector the yeasts. For example, Hawaiian strains of C. ipomoeae show evidence of having undergone a genetic bottleneck, most likely when the vector was introduced to the islands. The two haplotypes found in Hawaii were nearly identical and were also found in North and Central America. M. borealis had a more continuous distribution where the genetic markers follow latitudinal and longitudinal gradients.

A bridge to Brugada.

In acute cardiac care, prompt diagnosis and management is mandatory. The electrocardiogram (ECG) remains a crucial investigation in the management of ischemic heart disease and arrhythmias. A case is discussed, where the ECG changes caused by the Brugada syndrome and those caused by ischemia, aggravated by myocardial bridging, intertwine.

Bifurcation balloon for left main shock syndrome: facilitating the simultaneous percutaneous reperfusion of the LAD and circumflex.

Acute occlusion of the left main coronary artery frequently causes cardiogenic shock and, when this occurs with an initial TIMI 0 flow, has an extremely poor prognosis. The use of a bifurcation system has not been described previously in this situation but has advantages that may result in a simpler and quicker solution then other strategies. This case describes a distal LMCA occlusion, 2 weeks post-stenting of the proximal LAD and proximal Cx, where this strategy was successfully used as a bridge to surgery. Such a strategy may be crucially beneficial in this commonly fatal condition.