Psychiatry has suffered from the severe limitation of utilizing a phenomenologically based nosology of disease rather than a biological classification based on etiology and pathogenesis. As a consequence of this limitation, patient samples with a particular diagnosis are biologically heterogeneous and research results are frequently inconsistent and even contradictory. The need to develop a biologic classification is obvious and essential for psychiatry to take advantage of the developments in neuroscience. For example, the recent development of techniques for the in vivo examination of the nervous system makes it possible to identify pathophysiology associated with psychiatric populations. Initially, our focus has been on electrophysiologic correlates of clinical diagnosis. Currently, we are attempting to develop a taxonomy based on pathophysiology while seeking the clinical correlates of that classification.

Our first efforts have focused on quantitative electrophysiology because it is relatively nonintrusive and inexpensive. This approach is now being supplemented with newer techniques of studying the nervous system, including magnetic resonance imaging (MRI), single photon emission computerized tomography (SPECT), positron emission tomography (PET), and functional MRI.