How Ongoing Neuronal Oscillations Account for Evoked fMRI Variability

Abstract

Variability of evoked single-trial responses despite constant input or task is a feature of large-scale brain signals recorded by fMRI. Initial evidence signified relevance of fMRI signal variability for perception and behavior. Yet the underlying intrinsic neuronal sources have not been previously substantiated. Here, we address this issue using simultaneous EEG-fMRI and real-time classification of ongoing alpharhythm states triggering visual stimulation in human subjects. We investigated whether spontaneous neuronal oscillations-as reflected in the posterior alpha rhythm-account for variability of evoked fMRI responses. Based on previous work, we specifically hypothesized linear superposition of fMRI activity related to fluctuations of ongoing alpha rhythm and a visually evoked fMRI response. We observed that spontaneous alpha-rhythm power fluctuations largely explain evoked fMRI response variance in extrastriate, thalamic, and cerebellar areas. For extrastriate areas, we confirmed the linear superposition hypothesis. We hence linked evoked fMRI response variability to an intrinsic rhythm's power fluctuations. These findings contribute to our conceptual understanding of how brain rhythms can account for trial-by-trial variability in stimulus processing.

The Virtual Brain Integrates Computational Modeling and Multimodal Neuroimaging

“…Preprocessing of EEG (i.e., image-acquisition artifact and ballistocardiogram correction) and of fMRI data (motion correction, realignment, and smoothing) has been described elsewhere (Becker et al, 2011;Ritter et al, 2007Ritter et al, , 2008Ritter et al, , 2010.…”

“…Yet, gaining more insight about this relation is essential, since evidence attributes important functional roles to neuronal oscillations and synchrony. Changes of these variables are indicators for functionally relevant brain state alterations (Becker et al, 2011;Reinacher et al, 2009). TVB offers the possibility to explore both the interrelations of different types of neuronal activity and the neurohemodynamic coupling.…”

Neural Mechanisms Underlying Contextual Dependency of Subjective Values: Converging Evidence from Monkeys and Humans

“…Spontaneous fluctuations in brain activity can account for trial-to-trial variations in the neural response elicited by identical stimuli (Fox et al, 2006;Becker et al, 2011), as well as in perceptual decision and cognitive performance (Boly et al, 2007;Sadaghiani et al, 2009;Coste et al, 2011;Zhang et al, 2014). These considerations lead to the suggestion that trial-to-trial variations in prestimulus activity might persist into the stimulus-evoked response, thereby influencing behav-ioral response.…”

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