Garbage In Garbage Out: Test-Retest Reliability of Spectral Parameterization by FOOOF: Proceedings of Society for Psychophysiological Research Annual Meeting 2023

Spectral parameterisation techniques (i.e., FOOOF)
allow for the separation of aperiodic and periodic activity
in the electro-and magnetoencephalogram. Such
techniques allow the non-invasive measurement of
excitatory: inhibitory activity, and “pure” measurements
of periodic activity. While relevant to individual differences
in cognitive functions, little is known about the
psychometric properties of these techniques. We used
intraclass correlation coefficients (ICCs) to examine the
test-retest
reliability of parameterised activity at rest (eyes-open,
eyes-closed) and during three eyes-closed
tasks (arithmetic, music recall, and episodic memory recall;
n = 49) across three sessions (Session 1 and 2 90 minutes
apart, Session 3 30 days later). ICCs were good for the
aperiodic exponent and offset (ICCs > .70) and periodic
activity (ICCs > .66 for alpha and beta [power, central
frequency, and bandwidth]) in participants with clear
oscillations across conditions. Across all three sessions,
FOOOF performed poorly in resting eyes-open recordings
(40% of participants had poor fits and minimal oscillations
over noncentral sites) and test-retest reliability was poorer
for parameterised periodic activity. Thus, under the right
circumstances FOOOF provides reliable metrics of individual
differences in resting-state and task-based parametrised
neural activity. However, more work is needed to expand the circumstances under which FOOOF produces reliable results.