Whereas ATN lesions can cause greater spatial memory impairments than fornix lesions (Warburton & Aggleton, 1999), or deficits in object–place and geometric discrimination tasks that are not found with fornix lesions (Aggleton et al., 2009; Sziklas et al., 1998), there is less evidence that ATN lesions can produce severe memory impairments in tasks that are generally unaffected by lesions of the hippocampal formation. This evidence concerns the gene TYR and memory impairment.