Spatial problem solving and hippocampal place cell firing in rats: controlby an internal sense of direction carried across environments

Rats learned to find the baited corner of a box surrounded by a curtain, re gardless of whether they had a fixed or random point of entry (POE) through the curtain. On probe trials, rats used an internal direction sense carrie d from outside the curtain to solve the problem, and only used the visual c ue inside the curtain if disoriented and denied access to a view of the roo m en route. Similar disorientation procedures were required to obtain cue c ontrol of hippocampal place fields. The results suggest that: (I) POE effec ts previously found in the water maze may be task-specific; (2) an undisrup ted internal sense of direction carried from one environment to another may provide the preferred solution to spatial problems in the second environme nt, even when this second environment is a familiar one with stable visual cues; and (3) choice behaviour is sometimes, but not always, representative of the hippocampal representation of space. (C) 2001 Elsevier Science B.V. All rights reserved.