Electrophysiology of the prefrontal cortex in healthy controls and schizophrenic patients: a review

Prefrontal brain regions, in particular the anterior cingular gyrus (ACG), are altered in chronic schizophrenic patients and also play a pivotal role in physiological mechanisms of response control. A cued Continuous Performance Test (CPT) is a suitable paradigm for the investigation of response control, as it contains its fundamental mechanisms, i.e. the execution (Go) and the inhibition (NoGo) of an anticipated motor response. Previous electrophysiological investigations in healthy subjects during CPT execution revealed that the gravity center (centroid) of the event-related potential (ERP) elicited during the NoGo-condition is located more anterior as compared to the Go-condition in every single case. Moreover, by means of an electrophysiological source location method this NoGo-anteriorisation phenomenon (NGA) has been attributed to a strong brain electrical NoGo-hyperactivity located in prefrontal brain areas (ACG). Furthermore, the NGA has a superior test-retest reliability, a very high interindividual stability and is independent from age- and gender-effects. Systematic schizophrenic patients were characterized by a significantly diminished NGA indicating a dysfunction of prefrontal brain areas including the ACG. Based on these findings, the NGA has to be considered as a first electrophysiological measure for the quantitative assessment of ACG-function within a response control paradigm. Hopefully, this biological parameter will contribute to the elucidation of the etiopathogenetical background in different schizophrenic diseases.