Classification of schizophrenia patients and healthy controls using p100 event-related potentials for visual processing

Fixational eye movements and their associated evoked potentials during natural vision are altered in schizophrenia

Background

Visual exploration is abnormal in schizophrenia; however, few studies have investigated the physiological responses during selecting objectives in more ecological scenarios. This study aimed to demonstrate that people with schizophrenia have difficulties observing the prominent elements of an image due to a deficit mechanism of sensory modulation (active sensing) during natural vision.

Methods

An electroencephalogram recording with eye tracking data was collected on 18 healthy individuals and 18 people affected by schizophrenia while looking at natural images. These had a prominent color element and blinking produced by changes in image luminance.

Results

We found fewer fixations when all images were scanned, late focus on prominent image areas, decreased amplitude in the eye-fixation-related potential, and decreased intertrial coherence in the SCZ group.

Conclusions

The decrease in the visual attention response evoked by the prominence of visual stimuli in patients affected by schizophrenia is generated by a reduction in endogenous attention mechanisms to initiate and maintain visual exploration. Further work is required to explain the relationship of this decrease with clinical indicators.

Osteosíntesis en fracturas femorales periprotésicas de cadera Vancouver tipos B1 y C. Análisis multicéntrico

Introducción: Nuestro objetivo fue analizar los resultados del tratamiento con osteosíntesis en pacientes con fracturas Vancouver tipos B1 y C, evaluar las complicaciones, las reintervenciones y la tasa de mortalidad en este grupo. Materiales y Métodos: Estudio multicéntrico, retrospectivo. Se estableció una base de datos que incluía a 53 pacientes con fracturas periprotésicas de fémur Vancouver tipos B1 y C tratadas con osteosíntesis, desde 2008 hasta 2021, en dos centros hospitalarios de alta complejidad. Resultados: La fijación proximal más utilizada fue con tornillos bicorticales más lazadas de alambre. El tipo de fractura según la clasificación de Vancouver se correlacionó con un valor significativo en el uso de tornillos de compresión interfragmentaria (p 0,001), con un total de 13 pacientes (24,52%), 9 en fracturas Vancouver tipo C. El tiempo de consolidación promedio fue de 4 meses, con un puntaje promedio del Harris Hip Score de 68. Doce pacientes (22,64%) tuvieron complicaciones: retraso de la consolidación (7 casos; 13,2%), falla de la osteosíntesis con trazo de fractura a nivel distal del tallo (un caso; 1,88%), una nueva osteosíntesis por falla a nivel del material de osteosíntesis (un caso; 1,88%) y tres fallecieron (5,66%). Conclusiones: El manejo de las fracturas femorales periprotésicas es un tema complejo y desafiante. El tratamiento con osteosíntesis constituye un método exitoso que requiere de la aplicación de principios actuales de técnicas mínimamente invasivas que, junto con una fijación proximal estable, mejoran las posibilidades de éxito.

Discriminative analysis of schizophrenia using support vector machine and recursive feature elimination on structural MRI images

Structural abnormalities in schizophrenia (SZ) patients have been well documented with structural magnetic resonance imaging (MRI) data using voxel-based morphometry (VBM) and region of interest (ROI) analyses. However, these analyses can only detect group-wise differences and thus, have a poor predictive value for individuals. In the present study, we applied a machine learning method that combined support vector machine (SVM) with recursive feature elimination (RFE) to discriminate SZ patients from normal controls (NCs) using their structural MRI data. We first employed both VBM and ROI analyses to compare gray matter volume (GMV) and white matter volume (WMV) between 41 SZ patients and 42 age- and sex-matched NCs. The method of SVM combined with RFE was used to discriminate SZ patients from NCs using significant between-group differences in both GMV and WMV as input features. We found that SZ patients showed GM and WM abnormalities in several brain structures primarily involved in the emotion, memory, and visual systems. An SVM with a RFE classifier using the significant structural abnormalities identified by the VBM analysis as input features achieved the best performance (an accuracy of 88.4%, a sensitivity of 91.9%, and a specificity of 84.4%) in the discriminative analyses of SZ patients. These results suggested that distinct neuroanatomical profiles associated with SZ patients might provide a potential biomarker for disease diagnosis, and machine-learning methods can reveal neurobiological mechanisms in psychiatric diseases.

Deficits in Early Stages of Face Processing in Schizophrenia: A Systematic Review of the P100 Component

INTRODUCTION

Schizophrenia is associated with deficits in face and affect recognition, which contribute to broader social functioning deficits. The present aim was to conduct a meta-analysis of early face processing in schizophrenia, as indexed by the P100 event-related potential component.

METHODS

Twelve studies (n = 328 patients with schizophrenia, n = 330 healthy controls) of the P100 component during face processing were evaluated by calculating Cohen's d for each study and overall weighted mean effect size (ES). In additional exploratory analyses, moderating influences of method and design were investigated, and the P100 component during face processing was evaluated based on valence: 5 studies (n = 225 patients, n = 225 controls) included neutral stimuli, 5 studies (n = 225 patients, n = 225 controls) included happy stimuli, and 4 studies (n = 209 patients, n = 209 controls) included fearful stimuli.

RESULTS

The amplitude of the P100 to face stimuli was smaller in patients relative to controls (ES = .41, P < .01). Methodological or design differences did not account for heterogeneity in ES. When split by valence, results indicate smaller P100 in patients relative to control subjects in response to neutral (ES = .32, P < .001) and happy (ES = .21, P < .05) stimuli, whereas there was no difference in response to fearful faces (ES = .09, P > .05).

DISCUSSION

The results indicate that P100 amplitude in response to faces is smaller in patients with schizophrenia, showing that socially relevant visual processing deficits begin earlier in processing than previously suggested. Additionally, the exploratory analyses suggest emotional specificity in these deficits. Ramifications for our understanding of face processing deficits and treatment development are discussed.