The retrosplenial contribution to human navigation: a review of lesion and neuroimaging findings.

The clinical and neuroimaging literatures are surveyed in order to collate for the first time the available data on retrosplenial involvement in human navigation. Several notable features emerge from consideration of the case reports of relatively pure topographical disorientation in the presence of a retrosplenial lesion. The majority of cases follow damage to the right retrosplenial cortex, with Brodmann's area 30 apparently compromised in most cases. All patients displayed impaired learning of new routes, and defective navigation in familiar environments complaining they could not use preserved landmark recognition to aid orientation. The deficit generally resolved within eight weeks of onset. The majority of functional neuroimaging studies involving navigation or orientation in large-scale space also activate the retrosplenial cortex, usually bilaterally, with good concordance in the locations of the voxel of peak activation across studies, again with Brodmann's area 30 featuring prominently. While there is strong evidence for right medial temporal lobe involvement in navigation, it now seems that the inputs the hippocampus and related structures receive from and convey to right retrosplenial cortex have a similar spatial preference, while the left medial temporal and left retrosplenial cortices seem primarily concerned with more general aspects of episodic memory.