The hippocampus uses information just encountered to guide efficient ongoing behavior

Adaptive ongoing behavior requires using immediate sensory input to guide upcoming actions. Using a novel paradigm with volitional exploration of visuo-spatial scenes, we revealed novel deficits among hippocampal amnesic patients in effective spatial exploration of scenes, indicated by less-systematic exploration patterns than those of healthy comparison subjects. The disorganized exploration by amnesic patients occurred despite successful retention of individual object locations across the entire exploration period, indicating that exploration impairments were not secondary to rapid decay of scene information. These exploration deficits suggest that amnesic patients are impaired in integrating memory for recent actions, which may include information such as locations just visited and scene content, to plan immediately forthcoming actions. Using a novel task that measured the on-line links between sensory input and behavior, we observed the critical role of the hippocampus in modulating ongoing behavior.