Single-unit and polygraphic recordings in the awake, anaesthetic-free and head-restrained rat

In vivo investigation of the central nervous system is subject to interference with anaesthetic agents. Their influence on neural activity during electrophysiological recordings can be bypassed using a pre-implanted animal model, developed in the authors' laboratory. In this model, the preimplantation on the skull of a light device for further stereotaxic frame attachment allows, after a contention habituation period, classical electrophysiological approaches in the central nervous system of anaesthetic free-rats, The use of this model is compatible with repetitive single unit recordings. These experiments may be associated with other electrophysiological or physiological recordings such as electroencephalogram and electromyogram (EEG, EMG) or systemic/local pharmacological challenges (iontophoresis, pneumatic ejection). This technique allowed the authors to record simultaneously cortical activity and firing activity of basal ganglia neurones involved in movement disorders such as Parkinson's disease. The authors describe time-locked changes in firing pattern of subthalamic nucleus cells and cortical activity during vigilance state transitions in the normal rat.