ERPs Associated with and without an “Orienting Reflex” in Patients with Schizophrenia

Abstract

In this study, we measured traditional late components of the Event Related Potential (ERP: N 100, P 200, N200 and P 300) in a conventional auditory oddball paradigm, but additionally and simultaneously assessed electrodermal “orienting reflexes (ORs)” in 40 patients with schizophrenia and 40 age and gender matched normal controls. The single epoch ERPs that did and did not evoke an CR, were sub-averaged separately. The control subjects (but not the patient group), revealed delayed P 300 latency in the ERP sub-averages without ORs (ERP+OR), compared with ERP sub-averages with ORs (ERP−OR), Between-group analysis showed reduced N 100, N200 and P300 amplitudes (as well as delayed P300 latency) in the ERP−OR sub-average in patients with schizophrenia. In the ERP-Or sub-average, the patient group also had smaller N 100, N200 and P300 amplitudes, but larger P200 amplitude (compared with normal controls). This study shows the potential to tease out physiologically based OR sub-processes, by simultaneous acquisition and analysis of ERPs and autonomic electrodermal activity. Such ERP sub-averages (based on autonomic responses) high1ight that multiple processes overlap across the trial, and their delineation may elucidate more specific patterns of disturbance in schizophrenia, than traditional averaged measures.