The Hippocampus: From Memory, to Map, to Memory Map.

The hippocampus is one of the brain's great mysteries. Historically, theories of its function included emotion, response inhibition, general memory and spatial perception/learning, with memory versus space emerging as a particular focus of more recent debates. A 1978 paper by Olton and colleagues captured this dichotomy by exploiting their newly developed radial maze task to reveal a profound deficit in the ability of hippocampally lesioned rats to execute a spatial memory task. This finding supported the emerging spatial map theory of hippocampal function, and helped pave the way for the subsequent uncovering of an entire brain system linking space and memory.