Prefrontal structures involved in the continuous attention test performance as localised by the low-resolution electromagnetic tomography

Abstract Growing interest in higher cognitive functions intensifies the attempts to identify involved brain structures. Event-related potentials elicited by visual stimuli during the Continuous Attention Test were recorded from 49 healthy male subjects. The target was a direct repetition of any standard stimulus. Topography of the early P3 component was compared between both test conditions. The sources were localised by the low-resolution electromagnetic tomography (LORETA). The early P3 following standard stimuli dominated at scalp midline central/parietal leads, while the detection of the target resulted in a shift towards the prefrontal areas. The LORETA revealed activation in the anterior cingulate (ACC) and ventromedial prefrontal (VMPC) cortices during the detection of the target while in the standard condition the parietal cingulum was more active. These results (1) point at ACC and VMPC as involved in the detection of a context-defined target in a test of attention, (2) suggest various cognitive strategies dependent on the context of the stimulus, (3) support the hypothesis of functional subdivision within the cingulate cortex.