High resolution Electroencephalography in Freely Moving

26 Electroencephalography (EEG) is a standard tool for monitoring brain states in humans. 27 Understanding the molecular and cellular mechanisms underlying diverse EEG rhythms can 28 be facilitated by using mouse models under molecular, pharmacological, or 29 electrophysiological manipulations. The small size of the mouse brain, however, poses a 30 severe limitation in the spatial information of EEG. To overcome this limitation we devised a 31 polyimide based microelectrode array (PBM-array) with nanofabrication technologies. The 32 microelectrode contains 32 electrodes, weighs 150 mg, and yields noise-insensitive signals 33 when applied on the mouse skull. The high density microelectrode allowed both global and 34 focused mapping of high resolution EEG (HR-EEG) in the mouse brain. Mapping and 35 dynamical analysis tools also have been developed to visualize the dynamical changes of 36 spatially resolved mouse EEG. We demonstrated the validity and utility of mouse EEG in 37 localization of the seizure onset in absence seizure model and phase dynamics of abnormal 38 theta rhythm in transgenic mice. Dynamic tracking of the EEG map in genetically modified 39 mice under freely moving conditions should allow study of the molecular and cellular 40 mechanisms underlying the generation and dynamics of diverse EEG rhythms. 41