Relationship between regional hemodynamic activity and simultaneously recorded EEG-theta associated with mental arithmetic-induced workload
Article first published online: 1 NOV 2006
Copyright © 2006 Wiley-Liss, Inc.
Human Brain Mapping
Volume 28, Issue 8, pages 793–803, August 2007
How to Cite
Sammer, G., Blecker, C., Gebhardt, H., Bischoff, M., Stark, R., Morgen, K. and Vaitl, D. (2007), Relationship between regional hemodynamic activity and simultaneously recorded EEG-theta associated with mental arithmetic-induced workload. Hum. Brain Mapp., 28: 793–803. doi: 10.1002/hbm.20309
- Issue published online: 12 JUL 2007
- Article first published online: 1 NOV 2006
- Manuscript Accepted: 12 MAY 2006
- Manuscript Received: 6 OCT 2005
- electroencephalography (EEG);
- functional MRI (fMRI);
- mental arithmetic;
- frontal theta
Theta increases with workload and is associated with numerous processes including working memory, problem solving, encoding, or self monitoring. These processes, in turn, involve numerous structures of the brain. However, the relationship between regional brain activity and the occurrence of theta remains unclear. In the present study, simultaneous EEG-fMRI recordings were used to investigate the functional topography of theta. EEG-theta was enhanced by mental arithmetic-induced workload. For the EEG-constrained fMRI analysis, theta-reference time-series were extracted from the EEG, reflecting the strength of theta occurrence during the time course of the experiment. Theta occurrence was mainly associated with activation of the insular cortex, hippocampus, superior temporal areas, cingulate cortex, superior parietal, and frontal areas. Though observation of temporal and insular activation is in accord with the theory that theta specifically reflects encoding processes, the involvement of several other brain regions implies that surface-recorded theta represents comprehensive functional brain states rather than specific processes in the brain. The results provide further evidence for the concept that emergent theta band oscillations represent dynamic functional binding of widely distributed cortical assemblies, essential for cognitive processing. This binding process may form the source of surface-recorded EEG theta. Hum Brain Mapp, 2006. © 2006 Wiley-Liss, Inc.