An Event Related Potentials Study of Semantic CoherenceEffect during Episodic Encoding in Schizophrenia Patients

The objective of this electrophysiological study was to investigate the processing of semantic coherence during encoding inrelation to episodic memory processes promoted at test, in schizophrenia patients, by using the N400 paradigm. Eighteenschizophrenia patients and 15 healthy participants undertook a recognition memory task. The stimuli consisted of pairs of wordseither semantically related or unrelated to a given category name (context). During encoding, both groups exhibited an N400external semantic coherence effect. Healthy controls also showed an N400 internal semantic coherence effect, but this effect wasnot present in patients. At test, related stimuli were accompanied by an FN400 old/new effect in both groups and by a parietalold/new effect in the control group alone. In the patient group, external semantic coherence effect was associated with FN400, while,in the control group, it was correlated to the parietal old/new effect. Our results indicate that schizophrenia patients can processthe contextual information at encoding to enhance familiarity process for related stimuli at test. Therefore, cognitive rehabilitationtherapies targeting the implementation of semantic encoding strategies can mobilize familiarity which in turn can overcome therecollection deficit, promoting successful episodic memory performance in schizophrenia patients.