The most serious types of tumors are metastases and the gliomas. Seizure disorders: a seizure is a period of sudden, excessive activity of cerebral neurons. It is treated by large doses of vitamin b6: galactosemia is the inability to metabolize galactose (a sugar found in milk) It is a metabolic storage disorder where enzymes involved in waste degradation in lysosomes are missing: lysosomes increase in size and eventually lead to brain swelling and damage, this disease cannot be easily treated. Down syndrome: a congenital disorder that results in abnormal brain development, producing mental retardation. It may be caused by toxins present in the environment, faulty metabolism, and unrecognized infectious disorders: the standard treatment for parkinson"s disease is l-dopa (the precursor of dopamine) Gpi: lesions of the gpi releases the motor cortex of inhibition. Implanting electrodes in the subthalamic nucleus and attaching a device that allows the patient to electrically stimulate the brain through the electrodes.