The Lambda Wave as a Normal Physiological Phenomenon in the Human Electroencephalogram

Abstract

SEVERAL recent communications^1,2 have described a hitherto unobserved phenomenon in the human electroencephalogram. This consists of random monophasic waves (‘lambda waves’), appearing when the eyes are open, in the occipital or parietal regions. The phenomenon is believed to be rare, and a relationship to pathological conditions such as epilepsy or organic disease of the brain has been suggested. We have, however, recently obtained evidence suggesting that it is probably a normal physiological phenomenon which may be frequently unobserved owing to its very low voltage, its masking by background activity or both.