High-Density Electroencephalography in Freely Moving Mice

Abstract

Electroencephalography (EEG), an electrophysiological monitoring method to record the electrical activity of the brain, has been one of the most important noninvasive brain imaging tools in psychiatry, but surprisingly little is known about how the neural correlates of various EEG features are linked to cognition. Recent advances in neuroscience and related technologies make this an ideal time for new discoveries about the origin and significance of the contents of EEG. In particular, understanding the molecular and cellular mechanisms underlying diverse EEG features has been facilitated using mouse models under genetic, pharmacological, or optogenetic manipulations. A core challenge in mouse EEG was to obtain topographical neuroimaging that can be compared to human EEG. To overcome this challenge, we have developed a high-density EEG using a polyimide-based microarray that fits to the mouse skull and can be applied to various studies with a high spatiotemporal accuracy in free behavioral states. The benefits of mouse high-density EEG are not only that it provides cross-species neuroimaging data comparable to human EEG but also that it helps in dissecting enigmatic brain activity by probing the neural substrates of cognition when combined with optogenetics. The aim of this chapter is to introduce the methodological aspects of high-density EEG in mice. We explain the electrodes, surgery, recording, and analysis procedures and present applications in studying the origin of EEG signals. In addition, we point to potential areas where this technique will provide mechanical insight into circuit dysfunction in major psychiatric conditions.