A0688
Title: Quantifying time-varying sources in magnetoencephalography: A discrete approach
Authors: Zhigang Yao - National University of Singapore (Singapore)
Zengyan Fan - National University of Singapore (Singapore) [presenting]
Masahito Hayashi - Nagoya University (Japan)
William Eddy - Carnegie Mellon University (United States)
Abstract: The aim is to discuss the distribution of brain sources from the most advanced brain imaging technique, Magnetoencephalography (MEG), which measures the magnetic fields outside the human head produced by the electrical activity inside the brain. Common time-varying source localization methods assume the source current with a time-varying structure and solve the MEG inverse problem by mainly estimating the source moment parameters. These methods use the fact that the magnetic fields linearly depend on the moment parameters of the source, and work well under the linear dynamic system. However, magnetic fields are known to be non-lineally related to the location parameters of the source. The existing work on estimating the time-varying unknown location parameters is limited. We are motivated to investigate the source distribution for the location parameters based on a dynamic framework, where the posterior distribution of the source is computed in a closed form discretely. Both a dynamic procedure and a switch procedure are proposed for the new discrete approach, balancing estimation accuracy and computational efficiency when multiple sources are present. Lastly, we will discuss the source localization for the Brain-Controlled Interfaces data and illustrate that the new method is able to provide comprehensive insight into the time evolution of the sources at different stages of the experiment.
