Functional MRI correlates of resting-state temporal theta and delta EEG rhythms.

J Clin Neurophysiol. 2016 Oct 18;

Authors: Marawar R, Yeh HJ, Carnabatu C, Stern JM

Abstract
INTRODUCTION: The EEG rhythms demonstrate changes in frequency and power with spontaneous changes in behavioral state that do not have well understood metabolic correlates within the brain. To investigate this question and compare the temporal lobe theta and delta rhythms, resting-state functional MRI (fMRI) was obtained with simultaneous EEG.
METHODS: Simultaneous EEG-fMRI was recorded from 14 healthy, sleep-deprived subjects in awake and drowsy states. Scalp electrodes corresponding to bilateral temporal lobes were used to calculate delta and theta band power. The resulting time series was used as input in a general linear model and the final power curves were convolved with the standard, hemodynamic response function. Resulting images were thresholded at Z>2.0.
RESULTS: Positive and negative correlation for unilateral theta and delta rhythms were present bilaterally in different structures and with differing correlation sign. Theta rhythm positive correlation was present in hindbrain, peri-opercular, fronto-parietal regions and subcortical grey structures while negative correlation was present in parieto-occipital cortex. Delta rhythm positive correlation was present in parieto-occipital cortex and negative correlation roughly resembled positive correlations for the theta rhythm.
CONCLUSIONS: Temporal lobe theta and delta rhythms are correlated with fMRI signal in an almost mutually exclusive distribution. The different distributions indicate different corresponding networks. These normal findings supplement the understanding of theta and delta rhythm significance.

PMID: 27763967 [PubMed - as supplied by publisher]