Chronotype influences fMRI derived resting-state connectivity patterns.

Neuroimage. 2012 Aug 14;

Authors: Blautzik J, Peres I, Vetter C, Gutyrchik E, Keeser D, Berman A, Kirsch V, Mueller S, Pöppel E, Roenneberg T, Reiser M, Meindl T

Abstract
We investigated the influence of circadian rhythmicity and wake-up time on fMRI (functional Magnetic Resonance Imaging) derived resting-state data in 15 subjects by evaluating the time course of 20 brain connectivity patterns over 8h (4 sessions). For each subject, we determined the chronotype, which describes the relationship between the individual circadian rhythm and the local time. We detected highly significant correlations (r=0.82-0.9; p(corr)<0.00125) between chronotype and the daily time of maximum connectivity strength. Notably, this strong association was present for all 20 connectivity patterns, i.e., not only for the 16 patterns considered as resting-state networks, but also for 4 patterns that appeared to represent non-neural physiological noise (e.g., pulsation of cerebrospinal fluid or large vessels). This finding suggests that the observed circadian influence is not restricted to purely neural activity of the brain in the resting-state. No significant correlations were found between wake-up time and the daily time of maximum connectivity strength within any of the connectivity patterns (r=0.57-0.70, p(corr)>0.00125). We conclude that chronotype generally influences fMRI derived resting-state connectivity patterns, but not necessarily resting-state neural activity. We hypothesize that the association between chronotype and resting-state connectivity patterns is primarily based on circadian rhythms in cardiovascular and respiratory functions, which both may essentially account for the signal time courses measured with fMRI.

PMID: 22906784 [PubMed - as supplied by publisher]