ADHD — attention deficit hyperactivity disorder BFB — biofeedback ECG — electrocardiography/electrocardiographic/electrocardiogram EEG — electroencephalography/electroencephalographic/electroencephalogram EMG — electromyography/electromyographic/electromyogram EP — evoked potential GSR — galvanic skin response HR — heart rate PPG — photoplethysmography/photoplethysmographic/photoplethysmogram PTSD — post-traumatic stress disorder TTH — tension-type headache Introduction The biofeedback (BFB) technique...