A method for intra-cranial electrical stimulation in the pig using movable electrodes

This report describes a technique for the implantation of several movable electrodes in the brain of a pig, or other large mammal. The electrodes pass into the brain via a perforated acrylic block which serves as an electrode holder. The holder is surgically implanted into the skull and attached with dental cement and is protected by a stainless steel cap and lid. Electrical connection to individual electrodes is made through a 15 contact socket attached at the posterior end of the cap. A screw with a fine thread (approximately two turns per mm) passes through the lid of the cap and pushes down upon a brass plate which serves to lower the electrodes. This method provides fine control over the downward movement of the electrodes and the preparation has proved useful in the study of stimulation-bound feeding, drinking and self-stimulation.