Calibrating space: Exploration is important for allothetic and idiothetic navigation

Allothetic and idiothetic navigation strategies rely on very different cues and computational procedures. Allothetic navigation uses the relationships between external cues (visual, auditory, and olfactory) and mapping or geo metrical calculations to locate places. Idiothetic navigation relies on cue s generated by self-movement (proprioceptive cues or cues from optic, audit ory, and olfactory flow, or efference copy of motor commands) and path inte gration to locate a present location and/or a starting point. Whereas it is theorized that exploratory behavior is used by animals to create a central representation of allothetic cues, it is unclear whether exploration plays a role in idiothetic navigation. Computational models suggest that either a reference frame, calibrated by exploration, or vector addition, without r eference to exploration, could support path integration. The present study evaluated the contribution of exploration in these navigation strategies by comparing its contribution to the solution of both allothetic and idiothet ic navigation problems. in two experiments, rats were trained to forage on an open table for large food pellets, which they then carried to a refuge t o eat. Once trained, they were given probe trials from novel locations in e ither normal light, which permits the use of allothetic cues, or in infrare d light, which requires the use of idiothetic cues. When faced with a new p roblem in either lighting condition, the rats first explored the foraging t able before navigating directly home with the food. That exploration is equ ally important for allothetic and idiothetic navigation, suggests that both navigation strategies require a calibrated representation of the environme nt. (C) 1999 Wiley-Liss, Inc.