Pre-attentive Visual Processing in Alzheimer's Disease: An Event-related Potential Study

N2 Responses in Youths With Psychosis Risk Syndrome and Their Association With Clinical Outcomes: A Cohort Follow-Up Study Based on the Three-Stimulus Visual Oddball Paradigm

OBJECTIVE

Schizophrenia often occurs during youth, and psychosis risk syndrome occurs before the onset of psychosis. The aim of this study was to determine whether the visual event-related potential responses in youths with psychosis risk syndrome were defective in the presence of interference stimuli and associated with their clinical outcomes.

METHODS

A total of 223 participants, including 122 patients with psychosis risk syndrome, 50 patients with emotional disorders, and 51 healthy control subjects, were assessed. Baseline EEG was recorded during the three-stimulus visual oddball task. The event-related potentials induced by square pictures with different colors were measured. Almost all patients with psychosis risk syndrome were followed up for 12 months and were reclassified into three subgroups: conversion, symptomatic, and remission. The differences in baseline event-related potential responses were compared among the clinical outcome subgroups.

RESULTS

The average N2 amplitude of the psychosis risk syndrome group was significantly less negative than that in the healthy control group (d=0.53). The baseline average N2 amplitude in the conversion subgroup was significantly less negative than that in the symptomatic (d=0.58) and remission (d=0.50) subgroups and in the healthy control group (d=0.97). The average N2 amplitude did not differ significantly between the symptomatic and remission subgroups (d=0.02). However, it was significantly less negative in the symptomatic and remission subgroups than in the healthy control group (d=0.46 and d=0.38). No statistically significant results were found in the P3 response.

CONCLUSIONS

Youths with psychosis risk syndrome had significant N2 amplitude defects in attention processing with interference stimuli. N2 amplitude shows potential as a prognostic biomarker of clinical outcome in the psychosis risk syndrome.

Expert and Novice Goalkeepers' Perceptions of Changes During Open Play Soccer

In the present study we investigated expert and novice football (i.e., soccer) goalkeepers' three stages of perceiving changes in open play situations-detection, localization, and identification-with and without time constraints. We adopted the continual cycling flicker paradigm to investigate goalkeepers' perceptions when provided with sufficient time (Experiment 1), and we utilized the limited display one-shot change detection paradigm to study their perceptions under time constraints (Experiment 2). Images of goalkeepers' first-person views of open play soccer scenes were used as stimuli. Semantic or non-semantic changes in these scenes were produced by modifying one element in each image. Separate groups of expert and novice goalkeepers were required to detect, localize, and identify the scene changes. We found that expert goalkeepers detected scene changes more quickly than novices under both time allowances. Furthermore, compared to novices, experts localized the changes more accurately under time constraints and identified the changes more quickly when given sufficient time. Additionally, semantic changes were detected more quickly and localized and identified more accurately than non-semantic changes when there was sufficient time. Under time constraints expert goalkeepers' greater efficiency was likely due to pre-attentive processing; with sufficient time, they were able to focus attention to extracting detailed information for identification.