Spatial memory deficits in patients after unilateral selective amygdalohippocampectomy

The present study investigated the differential involvement of the right and left hippocampus in various forms of spatial memory: spatial search, positional memory versus object-location binding, and coordinate versus categorical processing. Twenty-five epilepsy patients with selective amygdalohippocampectomy were examined using a sensitive computer paradigm to measure these spatial memory aspects. The patients' performance was compared to a group of thirty healthy controls. The results show that the left amygdalohippocampectomy group performed poorly on the ability to bind together object information to coordinate spatial locations. In turn, the right amygdalohippocampectomy group was impaired in coordinate positional memory. Both patient groups were unimpaired on the spatial search task. These findings are discussed focusing on the "binding device" hypothesis in combination with the cognitive map theory.