Assessing the spatiotemporal evolution of neuronal activation with single-trial event-related potentials and functional MRI.
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.
Eichele
Tom
T
Department of Biological and Medical Psychology, University of Bergen, 5009 Bergen, Norway. tom.eichele@psybp@uib.no
Specht
Karsten
K
Moosmann
Matthias
M
Jongsma
Marijtje L A
ML
Quiroga
Rodrigo Quian
RQ
Nordby
Helge
H
Hugdahl
Kenneth
K
D000328:Adult; D001921:Brain / Q000166:cytology* / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009474:Neurons / Q000502:physiology*; D013997:Time Factors