Epidural EEG Recordings Using Microchips in Behavioural Context

Traditionally, behavioural and electrophysiological measurements in animals are performed separately; however their combined use has considerably enriched our understanding of, for example, memory-related processes. Especially single unit recordings paved the way and highlighted performance-specific firing characteristics of individual neurones (place cells, phase cell, head direction cell – see other contributions to this symposium). Less well explored is the correlation between behavioural activity and global brain activity recorded through the electroencephalogram (EEG), particularly in mice. This may be due to technical limitations both in terms of hardware and software, such as time-stamping of events and complex analytical issues. We here present the first EEG recordings from freely moving mice equipped with wireless microchips (Neurologger – NewBehavior). Unique features of the devices include 4 recording channels, an accelerometer to determine 3-D activity, and an infrared sensor for timestamping of external events. Devices were tested in two behavioural conditions in which previous use of videoobservation systems has provided behavioural indexes widely used to define and explain task performance.