Parkinson's disease. Coloured X-ray of a front view of the chest of a patient with Parkinson's disease, showing a battery pack implanted in the right side of the chest. The battery pack is connected by a wire to electrodes implanted in the thalamus region of the brain. Electrical stimulation of the thalamus helps to control the involuntary tremor experienced by Parkinson's disease sufferers. A control unit within the battery pack can be reset by a magnet to alter the level of stimulation given. A row of surgical staples were used to close the surgical wound. For an X-ray of the electrodes in place in the brain, see image M728/032.