Synchronization Tomography

A new brain imaging method pioneered by a German research group from several institutions can now produce images that localize the areas of the brain involved when test subjects perform physical activities, and can show how portions of the brain interact with each other. The technique, dubbed synchronization tomography, involves mapping the fluctuating magnetic fields produced by tiny electrical currents in the brain, and determining which brain regions are synchronized with an activity - such as a test subject's tapping finger. The researchers (Peter Tass, Institute of Medicine, Research Center, Juelich, 011+49-2461-61-2087) asked test subjects to tap their finger in time to a rhythmic tone, and to continue tapping at the same rate after the tone was switched off. Meanwhile, their brain activity was mapped with a magnetoencephalography (MEG) machine. The maps showed that the same regions of the brain areas are active both as people tapped to a beat and as they paced the tapping themselves, but that the synchronization between the different brain areas changes dramatically. Other brain imaging methods, including functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), can also provide insight into which regions of the brain are involved during various activities, but they take too long to acquire images to disclose how the brain regions interact with each other, and therefore overlook important details of brain function which are clearly revealed with synchronization tomography. In addition, a related synchronization technique may help in the study of rapidly changing signals in the heart detected with magnetocardiography systems. (P. A. Tass et al., Physical Review Letters, 28 February 2003)