Deep brain stimulation is a neurosurgical treatment for various neurological and psychiatric disorders. During such surgery, electrodes are placed in specific areas of the brain. For treatment with deep brain stimulation to be successful, the electrodes must be placed as precisely as possible in the brain. During the operation, fine electrodes can be used to measure electrical signals from brain cells and determine their exact location in the brain. However, administering anaesthetics during the operation can influence these electrical signals. This dissertation describes the effects of various anaesthetics on these electrical signals of the brain. These results provide better insight into the application of anaesthetics during deep brain s...