Enthusiastic and Excited response to the publication of “The entorhinal grid map is discretized” (Stensola, et al, Nature, 492, 72-78; 2012)
Background
The hippocampal formation is an amazing place, populated by strange characters called place cells, head-direction cells and grid cells. Hippocampal place cells exhibit “location-specific firing” (see figure). A single place cell will “fire” only when the rat crosses a restricted region of space. The figure below is an overhead-view map of the firing of a single place cell averaged over a 16-minute recording session (the animal was in a cylindrical enclosure; that’s why the map is round). John O;Keefe, followed by many others, has suggested that the collective firing of hippocampal place cells forms the rat’s “cognitive map”, and permits efficient navigation.