OLFACTORY CUES POTENTIATE LEARNING OF DISTANT VISUOSPATIAL INFORMATION

The influence of proximal olfactory cues on place learning and memory was tested in two different spatial tasks. Rats were trained to find a hole leading to their home cage or a single food source in an array o f petri dishes. The two apparatuses differed both by the type of reinf orcement (return to the home cage or food reward) and the local charac teristics of the goal (masked holes or salient dishes). In both cases, the goal was in a fixed location relative to distant visual landmarks and could be marked by a local olfactory cue. Thus, the position of t he goal was defined by two sets of redundant cues, each of which was s ufficient to allow the discrimination of the goal location. These expe riments were conducted with two strains of hooded rats (Long-Evans and PVG), which show different speeds of acquisition in place learning ta sks. They revealed that the presence of an olfactory cue marking the g oal facilitated learning of its location and that the facilitation per sisted after the removal of the cue. Thus, the proximal olfactory cue appeared to potentiate learning and memory of the goal location relati ve to distant environmental cues. This facilitating effect was only de tected when the expression of spatial memory was not already optimal, i.e., during the early phase of acquisition. It was not limited to a p articular strain. (C) 1997 Academic Press.