Head mountable device

A head mountable device for detecting a functional disorder of a brain in a patient, comprising:

• an opaque visor unit for positioning over eyes of the patient, wherein the visor unit includes:
• an arrangement of a plurality of LEDs positioned on an inside surface of said visor unit to which, during use, the eyes of the patient are exposed;
• a sensor housing including:
• three electroencephalogram (EEG) recording electrodes for measuring electrical potentials generated by the brain of the patient,
• an LED driver configured to control each of the plurality of LEDs independently to display a visual stimulus,
• a processor for controlling activation of the three EEG recording electrodes and the LED driver, and
• a battery for powering the LEDs and the processor;
• a headband coupling the sensor housing to the visor unit, wherein the LED driver is coupled to each of the plurality of LEDs by electrical connections from the sensor housing to the visor unit
• a first reference electrode configured to provide a reference point against which electrical potential signal data is measured by each of the three EEG recording electrodes;
• and
• a second reference electrode configured to provide a feedback cancellation signal;
• the device being configured to be mountable on a head of the patient such that when mounted on the head of the patient the plurality of LEDs are positioned before the eyes of the patient and the three EEG recording electrodes are positioned adjacent to an occipital lobe of the patient to receive signals from O1, O2, and Oz of the occipital lobe of the patient, respectively.