A total of 32 patients (21 with reversible and 11 with chronic Korsakov's syndrome of traumatic origin) and 20 healthy controls were studied. Visual and spectral coherence analysis was applied to EEG recordings and the three-dimensional localization of equivalent dipole sources of beta1 activity in the frequency range 13-20 Hz. Stable increases in the coherence of EEG beta1 activity generated by a limited number of sources (mostly frontobasal and brainstem locations) had negative prognostic significance in Korsakov's syndrome. Comparison with clinical data allow this EEG phenomenon to be linked to the inhibitory state of the corresponding cortical zones.