Hippocampal place cells are active when the rat is at certain locations. The sequence of these active place cells is known to be rapidly replayed during sharp-wave-ripple events in the EEG. In this issue of Neuron, a study by Gupta et al. challenges previous notions that the replayed trajectories are solely a passive echo of past episodes. Rather, replay might also be an active process construc...

Place cells are a fundamental component of the rodent navigational system. One intriguing implication of place cells is that humans, by extension, have "map-like" (or GPS-like) knowledge that we use to represent space. Here, we review both behavioral and neural studies of human navigation, suggesting that how we process visual information forms a critical component of how we represent space. Th...

Attractor neural network theory has been proposed as a theory for long-term memory. Recent studies of hippocampal place cells, including a study by Leutgeb et al. in this issue of Neuron, address the potential role of attractor dynamics in the formation of hippocampal representations of spatial maps.

The identification of 'place cells' in the hippocampus has suggested a special role for this brain structure in spatial mapping, but other studies have indicated a more general role in memory. New findings on place cells point the way towards a reconciliation of the mapping and memory views.