Learned association of allocentric and egocentric information in the hippocampus.

Single-cell recording was conducted in the hippocampus of rats that performed a spontaneous alternation task in a modified T-maze. In the central arm of the maze, 4 out of 45 cells (8%) were found that fired selectively depending on which turn the animals would take. This result is in disagreement with a previous study in which two-thirds of cells (22 out of 33) showed a clear bias for direction of turns. The interpretation was that the cells coded information of episodic memory. Our results do not support this hypothesis. Interestingly, over the course of training, an increasing number of cells were found that fired in correlation with the rats' movements. It is proposed that these cells associate egocentric motor information with allocentric spatial information rather than encode episodic memory.