The auditory P3a and P3b ERP components in schizophrenia: Relationship to frontal and temporal lobe MRI volumesB. F.O'Donnell, H. Ohta, R. W. McCarley, H. H. Hokama, C. G. Wible, S. Law, P. G. Nestor, R. Kikinis, F. A. Jolesz, M. E. Shenton
Recent Advances in Event-Related Brain Potential Research
Background. The P3b component of the event-related potential (ERP) to auditory target stimuli is usually reduced in schizophrenia, and the degree of reduction over left temporal recording sites has been related to left posterior superior temporal gyrus volume. We investigated the P3a and P3b components of the auditory ERP in schizophrenia (SZ), and their relationship to frontal and temporal lobe MRI volumes.
Methods.Fifteen male right-handed chronic SZ patients were compared with 20 gender and handedness matched control subjects. Both groups had a mean age of 41 years. An auditory discrimination paradigm was used to obtain the P3b component to target tones and a P3a component to novel sounds.
Results.Correlations with quantitative SPGR MRI ROI volumes for frontal and temporal lobe structures in SZ showed a distinctive pattern for P3a in that amplitude at frontal sites was positively correlated with medial temporal lobe ROI volumes (anterior hippocampus-amygdala). In SZ, both P3a and P3b were correlated with left temporal lobe neocortical structures, while superior frontal gyrus volume was correlated with P3b but not P3a amplitude (two-tailed p values < .05).
Conclusions.P3a and P3b both appeared vulnerable to abnormalities of the temporal lobe. P3a at frontal recording sites was best correlated with volumes of medial temporal lobe structures, suggesting that this input to frontal cortex may influence amplitude.