Synchrony in neuromagnetic oscillations as an indicator for coordination of brain activity underlying cognitive processes

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Cognition involves multiple brain areas and coordination of activity between these areas for successful function. One hypothesis is that precise timing plays a crucial role for coordination. Previous work using recording of neural activity with electrodes in the animal brain suggested that the relations of neural oscillations at various rhythms indicate coordination between brain areas. In humans we record related neuromagnetic signals noninvasively outside of the head with magnetoencephalography (MEG). Using mathematical methods for solving the 'inverse problem', we can estimate the brain activity generated at sources within the cortex. In this research program we are studying the synchrony between brain activity in two or more distant cortical sources. The inverse solution for source analysis may affect the observed synchrony measures. Therefore we will perform simulation studies to learn about the properties of our methods and to improve the sensitivity. In addition to synchrony of oscillations with the same rhythm another important principle is that brain rhythm at different frequencies interact with each other. It has been found that during a memory task, high frequency oscillations in the hippocampus occurred specifically at a certain phase of low frequency oscillations. We will develop new signal processing methods for detecting such interactions and coordinations between brain activities at different rhythms. We will apply the new brain research methods for studying how cognitive function changes with aging. One goal is to predict diseases like Alzheimer's at earliest stage in order to delay the onset of the disease through early intervention. We will use our brain imaging methods for monitoring the outcome of rehabilitation training. This is important for improving the rehabilitation programs. Behavioural measures are often not sensitive enough for differentiating between true learning effects and compensatory mechanisms. Moreover we will learn more about the role of brain oscillations for cognitive processes.