A method and a Cranial Electrical Stimulator CES for operation in a diagnosis, treatment, research, and test mode related to brain disorders, namely to mental disorders, and to neurological disorders, such as migraine and epilepsy, are disclosed. Diagnosis is based on a detected condition of passage of an electric signal via a pathway in the brain defined as passing from a first to a second electrode of a pair of electrodes from an array attached to the skull of a patient. Treatment is achieved by injecting a treatment signal in the pathway detected as having a condition.A practitioner operates a workstation of the CES that controls a signal and routing box SRB generating input signals and receiving output signal from the brain, via the skull and electrodes. The PC of the workstation controls signal input, output reception, measurement, display and storage in memory.