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P300 recordings during event-related fMRI: A feasibility study

UMR 7004-Applications Biologiques et Médicales de la RMN et Génie Biologique et Médical, Université Louis Pasteur (ULP)/Centre National de Recherche Scientifique (CNRS)/IFR 37 de Neurosciences, Strasbourg Cedex-France.
Cognitive Brain Research (Impact Factor: 3.77). 06/2005; 23(2-3):306-15. DOI: 10.1016/j.cogbrainres.2004.10.017
Source: PubMed

ABSTRACT Analysis of combined event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) can provide a high temporal and high spatial resolution to study functional cerebral processes. However, EEG data recorded inside an MR scanner is heavily distorted by artifacts. It is important in cognitive studies to ensure that recorded data reflect the same brain activity, and this is achieved through interleaved electroencephalographic (EEG) and fMRI measurements. Here, we demonstrate the feasibility of recording P300 ERPs during fMRI using a three-stimulus visual oddball task and involving a small number of trials for each stimulus. Ten EEG channels were acquired interleaved with fMRI images in five healthy subjects. The stimuli, including rare targets "X," frequent repetitive distractors "O," and rare distractors referred to as novels, were randomly presented every 2 +/- 1 s. The post hoc filter presented here was designed and applied to EEG data to remove the cardiac pulse artifact. Interleaved EEG/fMRI acquisition evidenced two P300 ERPs evoked at Fz, Cz, and Pz by targets and novels. Novel-related ERPs were of higher amplitude than their target-related counterparts. The fMRI maps acquired concurrently showed stronger BOLD response for target condition. We have shown that interleaved acquisition allows to obtain reliable P300 data and fMRI results, likely to shed light on the anatomical location of brain regions involved in cognitive ERPs relevant to many disorders affecting CNS functions. These noninvasive multimodal neuroimaging techniques can be used to explore and better understand processes underlying the functional brain organization.

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    • "C. Clean EEG data, after removal of ballistocardiogram (BCG) artifacts and bandpass filtering 0.5–45 Hz. Mulert et al., 2005; Otzenberger et al., 2005). Because the hemodynamic response peaks about 6 s after stimulus onset, whereas relevant ERP data can be collected within 1 to 2 s after stimulus onset, fMRI data collection can be done starting 2 s after stimulus onset and still provide event-related signals for the same events. "
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    • "Recently, there has been a growing interest in the use of simultaneous EEG-fMRI for evoked activity in cognitive paradigms , thereby obtaining functional datasets with both high spatial and temporal resolution. Thus, several groups have shown that it is possible to observe event-related potentials (ERPs) in the MR scanner that are similar to those obtained in regular conditions [Bonmassar et al., 1999; Kruggel et al., 2000; Liebenthal et al., 2003; Mulert et al., 2004; Otzenberger et al., 2005]. These first studies used interleaved EEG and fMRI recordings; more recently, a demonstration was done that showed that the ERPs could be obtained during actual scanning periods, after removal of scanning-related artifacts [Becker et al., 2005; Brandeis et al., 2003; Comi et al., 2005; Iannetti et al., 2005; Sammer et al., 2005]. "
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    ABSTRACT: There has recently been a growing interest in the use of simultaneous electroencephalography (EEG) and functional MRI (fMRI) for evoked activity in cognitive paradigms, thereby obtaining functional datasets with both high spatial and temporal resolution. The simultaneous recording permits obtaining event-related potentials (ERPs) and MR images in the same environment, conditions of stimulation, and subject state; it also enables tracing the joint fluctuations of EEG and fMRI signals. The goal of this study was to investigate the possibility of tracking the trial-to-trial changes in event-related EEG activity, and of using this information as a parameter in fMRI analysis. We used an auditory oddball paradigm and obtained single-trial amplitude and latency features from the EEG acquired during fMRI scanning. The single-trial P300 latency presented significant correlation with parameters external to the EEG (target-to-target interval and reaction time). Moreover, we obtained significant fMRI activations for the modulation by P300 amplitude and latency, both at the single-subject and at the group level. Our results indicate that, in line with other studies, the EEG can bring a new dimension to the field of fMRI analysis by providing fine temporal information on the fluctuations in brain activity.
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    • "We exploited the hemodynamic delay between neural activation and the associated BOLD response (approx. 5 s for 1.5 s stimulus duration, Miezin et al., 2000) to acquire EEG-data during the visual stimulation and fMRI data just afterwards (''sparse-sampling " imaging method, Ives et al., 1993; Bonmassar et al., 1999, 2001, 2002; Sommer et al., 2003; Otzenberger et al., 2005). Each fMRI volume (acquisition time, AT = 2.71 s) was acquired after each stimulation epoch, starting 1.1 s after the end of the stimulation block. "
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