Article

Assessing the spatiotemporal evolution of neuronal activation with single-trial event-related potentials and functional MRI. Proc Natl Acad Sci U S A

Department of Biological and Medical Psychology, University of Bergen, 5009 Bergen, Norway. tom.eichele@
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 01/2006; 102(49):17798-803. DOI: 10.1073/pnas.0505508102
Source: PubMed

ABSTRACT

The brain acts as an integrated information processing system, which methods in cognitive neuroscience have so far depicted in a fragmented fashion. Here, we propose a simple and robust way to integrate functional MRI (fMRI) with single trial event-related potentials (ERP) to provide a more complete spatiotemporal characterization of evoked responses in the human brain. The idea behind the approach is to find brain regions whose fMRI responses can be predicted by paradigm-induced amplitude modulations of simultaneously acquired single trial ERPs. The method was used to study a variant of a two-stimulus auditory target detection (odd-ball) paradigm that manipulated predictability through alternations of stimulus sequences with random or regular target-to-target intervals. In addition to electrophysiologic and hemodynamic evoked responses to auditory targets per se, single-trial modulations were expressed during the latencies of the P2 (170-ms), N2 (200-ms), and P3 (320-ms) components and predicted spatially separated fMRI activation patterns. These spatiotemporal matches, i.e., the prediction of hemodynamic activation by time-variant information from single trial ERPs, permit inferences about regional responses using fMRI with the temporal resolution provided by electrophysiology.

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    • "We decided to focus on the subsequent P3 that is thought to reflect a neural representation of a sensory process where the incoming stimulus is compared to the mental representation of the previous stimuli and the stimulus environment is updated. This is closely linked to concepts of orienting/surprise and predictive coding (Eichele et al., 2005). A later aspect of P3, the late positive complex (LPC) is thought to more closely represent working memory and response selection (Donchin, 1981; Coles, 1998, 2010; Polich, 2007). "
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    • "Given the orthogonal nature of the benefits and limitations of EEG and fMRI, it is a natural question to ask whether these measures can be combined in an effort to capitalize on the temporal and spatial resolutions provided by each modality. There currently exist several methods for " fusing " multimodal functional neuroimaging data together, such as partial least squares correlation (Lin et al., 2003; Martinez-Montes et al., 2004 ), independent component analysis (Beckmann and Smith, 2005; Liu & Calhoun, 2007; Calhoun et al., 2006; Eichele et al., 2009; Franco et al., 2008; Teipel et al., 2010; Xu et al., 2009; Calhoun et al., 2011;), structural equation modeling (Astolfi et al., 2004; Hamandi et al., 2008), multiple regression (De Martino et al., 2010; Eichele et al., 2005), and canonical correlation analysis (Correa et al., 2010a; Correa et al., 2010b; Correa et al., 2008). However, the focus of these methods is either source localization (for reviews, see Sui et al. (2012); Dähne et al. (2015)), or relating behavioral measures (e.g., response times) to brain data (for a review, see Krishnan et al. (2015) . "
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