Test-retest reliability of EEG spectra during a working memory task.
The inter-individual variation of EEG spectra is large even for the same cognitive task. We asked whether task-induced EEG spectra remain stable over more than a year. We recorded EEG in 41 healthy adults who performed a modified Sternberg task. In 20 subjects EEG was recorded in a second session with retest intervals 12-40 months. For electrodes AFz, Cz and Pz peak frequency and peak height were determined. We compared the curve shape of power spectra by regressing spectra pairwise onto each other and calculated a t-value. The t-value and pairwise differences in peak frequency and peak height between all sessions were entered into a generalized linear model (GLM) where binary output represents the recognition probability. The results were cross-validated by out-of-sample testing. Of the 40 sessions, 35 were correctly matched. The shape of power spectra contributed most to recognition. Out of all 2400 pairwise comparisons 99.3% were correct, with sensitivity 87.5% and specificity 99.5%. The intra-individual stability is high compared to the inter-individual variation. Thus, interleaved EEG-fMRI measurements are valid. Furthermore, longitudinal effects on cognitive EEG can be judged against the intra-individual variability in subjects.
Näpflin
Markus
M
Neurochirurgie, UniversitätsSpital Zürich, CH-8091 Zürich, Switzerland.
Wildi
Marc
M
Sarnthein
Johannes
J
D000328:Adult; D000368:Aged; D000465:Algorithms; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013647:Task Performance and Analysis