Path integrator contributions to hippocampal map formation

Skaggs and McNaughton's (J. Neurosci. 18(20) (1998) 8455) experiment in which rats shuttled between two visually identical boxes provided a clear demonstration of stable partial remapping in hippocampal place cells. Any satisfactory theory of hippocampal map formation must account for both the degree of remapping and the stability of the partially remapped state. We suggest that a weak path integrator (PI) input causes the remapping observed in this experiment. A computer simulation shows that while Hebbian learning on CA3 recurrent connections can draw maps together, concurrent Hebbian potentiation of the PI projection onto CA3 helps to stabilize the partially remapped state.