Illustration of a patient undergoing electroconvulsive therapy (ECT). The electrodes placed at the temples will deliver an electrical current that will induce a seizure in the patient's brain. Brain activity is monitored by the electrodes placed above the forehead. ECT is given under a general anaesthetic and the mouth guard prevents the patient from biting their tongue. ECT is used to treat some severe mental illnesses when other treatments haven't helped. It is effective in some cases, although why it works is Photographyt fully understood. Use of the treatment can be controversial, especially as in the past it was used while patients were still conscious and often without their consent.