Place Cells

 

A sample set of place cells, arranged in sequence of their maximal firing on a linear track.

Pyramidal cells in the rodent hippocampus fire in a spatially localized manner. The Nobel prize was recently award to John O’Keefe for his discovery of such “place cells”.   A typical place cell will fire action potentials at a rate varying from zero Hz when the animal is outside of its “place-field” to up to 40 Hz when the animals is at the most “preferred” location of that cell.

Despite this tremendous advance, much remains unknown about how place-cell activity allows the hippocampus to encode episodic memory, in which it plays a well-established role.

There is a very nice online resource for more information about place cells created by Eric Hargreaves at NYU.  You may also check the webpage on Wikepedia.

In our lab, we use the sequential firing of place cells, when a rat run across an environment, to create a mnemonic sequence template that gives the hippocampal neural correlate of the rodent’s experience.  We observed forward and reverse replay of the experiential place-cell sequences during rest epochs, when the rat was no longer running.