Frontal theta and posterior alpha in resting EEG: A critical examination of convergent and discriminant validity

Abstract

Prior research has identified two resting EEG biomarkers with potential for predicting functional outcomes in depression: theta current density in frontal brain regions (especially rostral anterior cingulate cortex) and alpha power over posterior scalp regions. As little is known about the discriminant and convergent validity of these putative biomarkers, a thorough evaluation of these psychometric properties was conducted toward the goal of improving clinical utility of these markers. Resting 71-channel EEG recorded from 35 healthy adults at two sessions (1-week retest) were used to systematically compare different quantification techniques for theta and alpha sources at scalp (surface Laplacian or current source density [CSD]) and brain (distributed inverse; exact low resolution electromagnetic tomography [eLORETA]) level. Signal quality was evaluated with signal-to-noise ratio, participant-level spectra, and frequency PCA covariance decomposition. Convergent and discriminant validity were assessed within a multitrait-multimethod framework. Posterior alpha was reliably identified as two spectral components, each with unique spatial patterns and condition effects (eyes open/closed), high signal quality, and good convergent and discriminant validity. In contrast, frontal theta was characterized by one lowvariance component, low signal quality, lack of a distinct spectral peak, and mixed validity. Correlations between candidate biomarkers suggest that posterior alpha components constitute reliable, convergent, and discriminant biometrics in healthy adults. Component-based identification of spectral activity (CSD/eLORETA-fPCA) was superior to fixed, a priori frequency bands. Improved quantification and conceptualization of frontal theta is necessary to determine clinical utility.

Variability and effect sizes of intracranial current source density estimations during pain: Systematic review, experimental findings, and future perspectives

“…As many researchers have reported, participants exhibited higher alpha activity in parietal and occipital regions during eyes-open resting state (Barry & De Blasio, 2017;Chen, Feng, Zhao, Yin, & Wang, 2008;Pitchford & Arnell, 2019;Smith et al, 2020). Therefore, the higher signal-to-noise ratio in the alpha band at S1 may be to a large extent responsible for the higher reliability (Elkum & Shoukri, 2008).…”

Open science in psychophysiology: An overview of challenges and emerging solutions

“…Multi-site studies, in which the same research is conducted at different sites, are desirable because they enable researchers to increase statistical power by increasing the total sample size of the study, promote transparent practices, facilitate communication between researchers, and foster quality control. Pooling data from multiple sites is critical in studies of rare disorders and other populations that are difficult to recruit from (Smith et al, 2020;Swerdlow et al, 2007). Replication of a given effect across different laboratories tends to increase confidence in the robustness of that effect, especially in the case of surprising or counter-intuitive effects (Bekhtereva et al, 2018).…”

Open Science in Psychophysiology: An Overview of Challenges and Emerging Solutions

“…Multi-site studies, in which the same research is conducted at different sites, are desirable because they enable researchers to increase statistical power by increasing the total sample size of the study, promote transparent practices, facilitate communication between the researchers, and foster quality control. Pooling data from multiple sites is critical in studies of rare disorders and other populations that are difficult to recruit from (Smith et al, 2020;Swerdlow et al, 2007). Replication of a given effect across different laboratories tends to increase confidence in the robustness of that effect, especially in the case of surprising or counter-intuitive effects (Bekhtereva et al, 2018).…”