Neural representations across species

A plethora of studies in rodents have described spatially tuned neurons, including place cells in the hippocampus and grid cells in the medial entorhinal cortex (MEC), suggesting a crucial role of the hippocampal formation in spatial navigation (1). Human studies have, in turn, shown that the hippocampal formation is involved in declarative memory (memories of facts and events) (2). What, then, is the function of the hippocampus? Is it involved in memory or in spatial navigation, or does it have a more general function that encompasses both? Several studies have shown that place cells remap, changing the location at which they respond, following geometrical changes in the environment, and that they can be modulated by nonspatial factors, according to the animals' specific tasks (3).