Propagation of hippocampal activity in ultra-high risk schizophrenia psychosis subjects using Independent Component Analysis

Table of Contents

Introduction

Schizophrenia and Visual Working Memory

Ultra-High-Risk of psychosis

Ultra-High-Risk of psychosis and Visual Working Memory

Hippocampus and Visual Working Memory

Hippocampal Impairments in Schizophrenia

The P300 event related potential

P300 Impairments in Schizophrenia

The P300 as a putative biomarker of psychosis risk

Detecting hippocampal activity through scalp EEG

Rationale, Aims and Hypotheses

Methods

Participants

Pilot study sample

PSYSCAN study sample

Inclusion and exclusion criteria

Ethical considerations

Visual Working Memory Task (based on Hannula, 2015)

Design and Procedure

EEG Data Acquisition and analysis

ERP Processing

Statistical Analysis

Results

Pilot Study Analysis

Demographics

ERPs

Visual Analysis of EEG 3D Amplitude Maps

Power Analysis

PSYSCAN Study Analysis

Demographics

ERPs

Independent samples t-test

Visual Analysis of EEG 3D Amplitude Maps

Discussion

P300 ERP components in a visual working memory task

Mesial sources contribution to scalp EEG

Hippocampus activation and Visual Working Memory

P300 ERP in UHR subjects

Hippocampal activity detection in UHR subjects

Strengths of the current study

Limitations of the current study

Future directions

Conclusion

Objectives and Topics

This research aims to investigate the neurobiological basis of visual working memory (VWM) deficits in individuals at ultra-high risk (UHR) for psychosis by utilizing the P300 event-related potential (ERP) as a biomarker and attempting to detect hippocampal activity through scalp EEG. The primary research question centers on whether hippocampal activity can be delineated during VWM tasks and if differences in P300 amplitude and latency exist between UHR individuals and healthy controls.

• Visual Working Memory (VWM) in schizophrenia and UHR subjects
• Hippocampal function and its contribution to scalp EEG signals
• The P300 ERP as a potential physiological biomarker for psychosis risk
• Methodological application of Independent Component Analysis (ICA) for source delineation

Excerpt from the book

Summary of Chapters

Introduction: Provides a comprehensive overview of cognitive deficits in schizophrenia, the specific challenges in visual working memory, and the clinical importance of the ultra-high-risk (UHR) state for early intervention.

Methods: Details the recruitment of participants, ethical considerations, the design of the visual working memory task, and the specific EEG data acquisition and preprocessing steps, including ICA.

Results: Reports the findings from both the pilot study and the PSYSCAN study, focusing on P300 amplitude and latency differences and the visual analysis of EEG 3D amplitude maps to localize hippocampal activity.

Discussion: Interprets the findings regarding P300 components, the successful detection of mesial temporal activity via scalp EEG, and compares results with previous literature to highlight the role of the hippocampus in VWM.

Conclusion: Summarizes the methodology as a stepping stone for future research into biomarkers of psychosis and emphasizes the potential of utilizing sLORETA for further source localization.

Keywords

Schizophrenia, Ultra-High-Risk (UHR), Visual Working Memory (VWM), P300, Hippocampus, Electroencephalography (EEG), Independent Component Analysis (ICA), Biomarkers, Cognitive deficits, Event-related potentials (ERP), Neurodevelopmental model, Prodromal stages, Source localization, Psychosis, Mesial temporal sources.

Frequently Asked Questions

What is the primary objective of this research dissertation?

The research aims to delineate hippocampal activity during visual working memory tasks and explore whether P300 ERP components can serve as biomarkers for individuals at ultra-high risk (UHR) for psychosis.

Which key areas are examined in this study?

The study examines the cognitive deficits in schizophrenia, the specific nature of UHR psychosis, the role of the hippocampus in working memory, and the electrophysiological properties of the P300 component.

What is the central research hypothesis?

The study hypothesizes that P3a and P3b ERPs can be detected using a VWM task, that UHR subjects will show reduced P300 amplitudes and delayed latencies compared to controls, and that hippocampal activity is detectable via cheekbone electrodes.

What scientific methodology is utilized?

The research utilizes cross-sectional scalp EEG, applying Independent Component Analysis (ICA) to preprocess signals and detect artifacts, combined with visual analysis of 3D amplitude scalp maps.

What does the main body of the work address?

The main body details the experimental procedures, data acquisition from both a pilot study and the PSYSCAN study, and provides a statistical analysis comparing ERP waveforms between UHR subjects and healthy controls.

Which keywords characterize this work?

Key terms include Schizophrenia, Ultra-High-Risk, P300, Hippocampus, EEG, ICA, VWM, and biomarkers.

Why is the hippocampus significant in this study?

The study investigates the hippocampus because empirical evidence links it to working memory maintenance of novel items, and the researchers aim to identify its activity through non-invasive scalp EEG, which is typically considered difficult.

What were the findings regarding hippocampal activity in UHR subjects?

The study successfully detected a similar pattern of hippocampal activity in UHR participants as in the pilot sample, occurring between the 310-350 millisecond time window, suggesting its involvement in the retention of visual information.

How does this study contribute to existing literature?

It provides a potential methodology for identifying mesial temporal activity using only scalp EEG and offers new insights into how visual working memory tasks can be used to elicit responses from the hippocampus in at-risk populations.