Influence of arousal level for functional magnetic resonance imaging (fMRI) study: simultaneous recording of fMRI and electroencephalogram.

Simultaneous recording of functional MRI (fMRI) and electroencephalogram (EEG) has been applied to several clinical fields, making it possible to monitor the arousal level of the subject during a cognitive task. The study confirmed that activated cerebral areas were different between high and low arousal levels during the smooth-pursuit eye movement task. When arousal level was high, activations in the parietal eye field, frontal eye field (FEF), supplementary eye field (SMA), visual fields (V1) and occipito-temporal junction (V5) were found. In contrast, when arousal level was low, activations were found only in V1 and FEF. The results indicate that the monitoring of the arousal level of subjects using fMRI and EEG recordings simultaneously is crucial for detecting cortical activations during a cognitive task.