Brain network and electrophysiological representations of dynamic thought

Abstract

Scientists have long sought to understand the biological basis and function of diverse thoughts through various lenses, emphasizing aspects of content, affect, sensory experience, and process. An often-missing piece to this search is the investigation of the neural correlates of thought from a dynamic framework, particularly how thoughts are constrained through deliberate control or through automatic orientation to salient stimuli. Shedding light on the dynamics of thought is crucial to understanding brain-behavior relationships, human cognition, and mental health. The present study examines an archival dataset combining simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to identify neural bases underlying these dimensions of thought during quiet, wakeful rest. Participants completed two resting-state sessions with intermittent probes measuring self-reported automatic and deliberate constraints of thought. Three fMRI-based networks, the default network, frontoparietal control network, and salience network, were investigated for their hypothesized roles in supporting cognitive constraints on thought. EEG data underwent extensive scanner artifact correction and were decomposed into spectral frequencies, with an emphasis on canonical alpha, beta, and theta activity. Spectral features of EEG and fMRI dynamic functional connectivity and network activation were analyzed using hierarchical Bayesian linear models (HBLMs) to assess the power of individual features to predict probe ratings. A total of 13 HBLMs were built to predict thought constraint ratings from neural features. Results showed that deliberate constraint ratings were significantly predicted by widespread alpha (8-12Hz) EEG data (p = 0.0414) with a large effect size (R² = 0.33). The remaining 12 models were non-significant and showed substantial individual variability in neural representations of dynamic thought. Overall, findings from this study suggest that alpha power acts as a neural marker of deliberate constraint and reinforce the importance of continued investigation to further elucidate the neural underpinnings of dynamic thought.