ABSTRACT
This chapter reviews neurobehavioral data on distinctive brain systems that deter mine how events are processed as familiar or novel. These processes are initiated and terminated by an orienting reaction that signals the boundaries of an episode. Within an episode, familiarity is based on processing relevance, novelty on restructuring currently irrelevant events. The amygdala and hippocampal systems are critically implicated: Amygdalectomized animals are deficient in processing currently relevant (i.e., reinforcing or deterrent), hippocampectomy results in deficient processing of currently irrelevant events.
