I have investigated a neuronal hypersynchronism, currently included under t
he general subject of epilepsy, and termed interictal activity. I suggest t
hat it is a physiological activity of the mammalian brain and propose it be
termed Hyperia. After a thorough study of the extraordinary psychic manife
stations of this neuronal hypersynchronism shown by mystics and artists, I
have reviewed several scientific publications bearing on my hypothesis. I c
onclude by elaborating on a variety of cerebral hypersynchronous functions
whose cause I consider to be physiological. Such behaviour is a common basi
s for extraordinary psychic manifestations found not only in mystics and ar
tists, but also in patients suffering from endogenous psychoses, especially
Bipolar Disorder. (C) 2001 Harcourt Publishers Ltd.