Neural basis of the spatial navigation based on geometric cues.

Recent studies have found that hippocampus of mammals and birds and the lateral pallium of the fish telencephalon are critical for learning the geometric properties of space. Nevertheless, other studies suggest that navigation based on geometric information is primarily supported by proximal cues near the target location. According to this hypothesis, animals could use a taxon strategy to navigate an environment where only geometric cues are available and the results from lesion studies could be masking other effects related to the use of featural information. In the present study, we examined the effects of lesions to the lateral pallium of goldfish in the encoding of geometric spatial information. Goldfish with telencephalic lesions were trained to search for a goal in a rectangular-shaped arena with either one or two possible goals. Lateral pallium lesions do not interfere with goal location when the geometric information defined the goal unambiguously. Present results suggest that the geometric information is sensitive to be encoded in taxon strategies and therefore it could not depend directly on the correct functioning of the hippocampal system.