Making movies of children's cortical electrical potentials: A practical procedure for dynamic source localization analysis with validating simulation

Abstract

Dipole source localization analysis (DSLA) of brain's event-related electrical potentials (ERPs) often presumes time constraints potentially too rigid to capture complex neural dynamics. We present a practical procedure (dynamically-guided DSLA) combining in a novel way well-established off-the-shelf modeling (Independent Component Analysis, and proprietary software modules running on MATLAB, such as FASTICA and EEG-Lab DIPFIT) with the cognitive modeling simulation framework tool known as Adaptive Control of Thought-Rational (ACT-R). The integration of these multiple methods can narrow down the time-windows of interest for DSLA more flexibly. As a demonstration, we used dynamically-guided DSLA to re-analyze cluster-level ERPs from a visual target detection task involving the participation of 26 preschool children. The key analytic features were dynamic ERP movies vis-à-vis validating ACT-R simulation of comparison adult data for the same task. Spatial topography for the six estimated sources did not differ significantly in children's and adult simulated data, which generally showed high fit (predicted R2 > 0.97). A control comparison using the static DSLA showed discrepant fits for two sources, suggesting that dynamic DSLA may offer higher discriminant reliability. Given its high validity, flexibility and relative user-friendliness, dynamically-guided DSLA seems useful for assessing developmental homology and may be suitable for a variety of clinical and experimental applications specifically involving neurodevelopmental data. Statement of SignificanceAccurately determining the location of neural activity observed via electroencephalogram remains a well-known challenge. Under a variety of conditions, conventional dipole source localization analysis methodologies can result in underqualified data. In this work we present a novel process, known as dynamically-guided DSLA, which demonstrates how pre-existing tools can be appropriated to facilitate the examination and analysis of neurological activity in preschool-aged children. Because the effects exerted by a stimulus or event on EEG signals can be linked to behaviors and actions, at different levels of physical mechanisms of different degree of complexity, this neuroimaging tool offers the opportunity to cut across multiple layers of physical systems underlying cognitive and emotional functions, and therefore can be leveraged to reach invaluable insights. We highlight how the proposed technique can help link the electrophysiology to underlying physical alteration (e.g., neurodevelopmental disease); and how the proposed combination of methodologies can help "reverse engineer" physical defects or anomalies (and their locations) to quantify the EEG measurements in terms of dynamic interactive physical phenomena (movie of topographically mapped brain activity), as opposed to just giving a number against a disease or identifying a brain location.