EEG-based brain imaging techniques in psychiatry.

Electroencephalography has probably represented the first modern and scientifically sound attempt to functionally explore the in vivo activity of the human brain and it has, since ever, attracted attention of psychiatrists, from both the clinical and the research viewpoint. Probably due to the limitations implied by their traditional low spatial resolution, the use of psychophysiological techniques in psychiatry has been not continuous over the last century; however, the availability of newer EEG-based brain imaging techniques has recently renovated some interest (1) ). Furthermore, recent theories proposed that psychopathology may result from the failure to integrate the activity of different areas involved in cognitive processes, rather than from the impairment of one or more brain areas (2) ); within this view, a reliable brain imaging tool should be able to explore the dynamics of complex interactions among brain regions, with high sensitivity to the subtle deviation in complex processes that last fractions of seconds; psychophysiological techniques, indeed, offer the possibility to explore the functional correlates of major psychiatric illnesses, as well as to understand of the effects of psychotropic drugs on the central nervous system, with incomparable time resolution. Finally, the recent technical possibility to combine different brain imaging approaches has further fostered a renovated enthusiasm to ward the use of EEG-based techniques in psychiatry. This contribution will provide an historical overview of the EEG-based brain imaging techniques and an update on some recent advances concerning the use of such techniques within the psychiatric field. Finally, some examples of psychophysiological and ''multimodal'' imaging investigations in subjects with different psychiatric conditions will be provided.