Resetting the path integrator: a basic condition for route-based navigation

Abstract

During short excursions away from home, some mammals are known to update their position with respect to their point of departure through path integration (dead reckoning) by processing internal (idiothetic) signals generated by rotations and translations. Path integration (PI) is a continuously ongoing process in which errors accumulate. To remain functional over longer excursions, PI needs to be reset through position information from stable external references. We tested the homing behaviour of golden hamsters (Mesocricetus auratus W.) during hoarding excursions following a rotation of the arena and nest. In continuous darkness, the hamsters returned to their point of departure at the rotated nest, and therefore depended on PI only. In other trials, the animals were briefly presented with visual room cues during or at the end of the outward trip, visual cues being pitted by 67°or 98°against the animal's current selfgenerated position vector. After a fix, the animals headed for the usual (unrotated) nest location, as defined by room cues, independent of the timing of the fix. These results were obtained in two different geometrical settings and showed that, after the fix, the animals update their position, and not merely their head direction or internal compass, in a new reference frame. Thus, episodic fixes on familiar external references reset the PI and therefore greatly enhance the functional signification of navigation that is based on feedback information from locomotion.

Homing in rocky intertidal fish. Are Lipophrys pholis L. able to perform true navigation?

“…For example, in hamsters, visual landmarks reset the path integrator. When testing the homing behavior of golden hamsters in a circular arena in which the position of the nest can be rotated relative to the departure point, Etienne et al (2004) showed that in continuous darkness, the hamsters returned to their point of departure at the rotated nest and therefore depended on path integration only. However, if visual cues from the room were briefly presented, the animals headed for the usual nest location, as defined by room cues, showing that landmarks can reset the path integrator.…”

“…In mice, animals transported inside their nests failed to integrate the displacement (Alyan 1996). Moreover, L. pholis individuals were transported to the release site with no access to visual cues throughout the entire outward journey, as such cues are essential to correct errors of the path integrator in cases of displacement with tortuous detours (Etienne et al 2004;Collett and Graham 2004). Together, these procedures make path integration information potentially unusable.…”

Active and passive contributions to spatial learning

“…It is possible that idiothetic information is more useful for spatial updating in a small-scale environment than for learning survey knowledge in a large-scale space. Longer paths may lead to increasing drift in path integrationparticularly, vestibular information-eventually rendering it unreliable for estimating distance and direction (see Collett, Collett, Chameron, & Wehner, 2003;Etienne, Maurer, Boulens, Levy, & Rowe, 2004;Etienne, Maurer, & Séguinot, 1996;Müller & Wehner, 2010, for the drift and resetting of path integration in animals). To test this hypothesis, Waller, Loomis, and Steck (2003) varied the magnitude and fidelity of vestibular information that participants had access to while exploring a large realworld environment.…”

Cognition in Invertebrates

“…Early experiments showed that with increasing experience of the terrain, directional information available during the inbound flight may be computed for the purpose of directional indication in the waggle dance (Otto, 1959). If the waggle dance computes directional information which depends not only on the current state of the animal's path integrator, but also on information that the animal has associated with landmark views, that is, local vectors associated with landmarks (Etienne et al, 2004), navigating bees would rely not only on an egocentric, but also on a geocentric system of reference.…”