This research is designed to apply neuromagnetic recordings, EEG evoked potential recordings, and NMR imaging to answer several specific questions about altered brain mechanisms in schizophrenia. Schizophrenic patients may exhibit impaired central and/or cortical inhibition leading to a type of sensory "flooding". We will investigate this with studies measuring auditory evoked magnetic fields (AEFs) and auditory evoked potentials (AEPs). We will study the response amplitude/stimulus intensity functions of the AEF M100 and the AEP N100, and estimate the extent to which previously described alterations in the amplitude of this evoked potential component are due either to alterations in local cellular firing in auditory cortical regions or to alterations in more diffuse nonspecific sources. Studying the AEP P50 and AEF N50 components in the conditioning-testing paradigm, we will determine whether AEFs exhibit similar evidence of altered inhibitory function as has been previously described for AEPs and we will make an assessment of the extent to which this activity is a function of altered cellular activity or more nonspecific sources.

We will utilize neuromagnetic mapping techniques to localize the intracerebral source of the P50 and M50 and then, using NMR imaging, identify the anatomical structures present at that site. We will also assess ventricular size and ventricular brain ratios, to see if they correlate with other measures of impaired inhibitory functions.

Finally, we will study several populations of psychotic patients who are not schizophrenic to permit the establishment of exclusionary criteria relative to the most robust of our findings, and we will begin studies on the sensitivity and specificity of our findings.

R01MH041396

1986-06-01

1989-03-31