SN instructed that a seizure that begins in the occipital cortex may result in flashing lights, while a seizure that affects the motor cortex will result in rhythmic jerking movements of the face, arm, or leg on the side of the body opposite to the involved cortex (Jacksonian seizure). A seizure that begins in the parietal cortex may cause distortion of spatial perception; a seizure that begins in the dominant frontal lobe may cause sudden speech difficulties.