title: Interindividual variation in fornix microstructure and macrostructure is related to visual discrimination accuracy for scenes but not faces.
abstract: Transection of the nonhuman primate fornix has been shown to impair learning of configurations of spatial features and object-in-scene memory. Although damage to the human fornix also results in memory impairment, it is not known whether there is a preferential involvement of this white-matter tract in spatial learning, as implied by animal studies. Diffusion-weighted MR images were obtained from healthy participants who had completed versions of a task in which they made rapid same/different discriminations to two categories of highly visually similar stimuli: (1) virtual reality scene pairs; and (2) face pairs. Diffusion-MRI measures of white-matter microstructure [fractional anisotropy (FA) and mean diffusivity (MD)] and macrostructure (tissue volume fraction, f) were then extracted from the fornix of each participant, which had been reconstructed using a deterministic tractography protocol. Fornix MD and f measures correlated with scene, but not face, discrimination accuracy in both discrimination tasks. A complementary voxelwise analysis using tract-based spatial statistics suggested the crus of the fornix as a focus for this relationship. These findings extend previous reports of spatial learning impairments after fornix transection in nonhuman primates, critically highlighting the fornix as a source of interindividual variation in scene discrimination in humans.
authors.affiliation: Wales Institute of Cognitive Neuroscience, Cardiff University Brain Research Imaging Centre, School of Psychology, and Neuroscience and Mental Health Research Institute, Cardiff University, CF10 3AT, United Kingdom, and PostansM@cardiff.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Postans
authors.affiliation: Wales Institute of Cognitive Neuroscience, Cardiff University Brain Research Imaging Centre, School of Psychology, and Neuroscience and Mental Health Research Institute, Cardiff University, CF10 3AT, United Kingdom, and.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Hodgetts
authors.affiliation: School of Psychology and Psychiatry, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Mundy
authors.affiliation: Wales Institute of Cognitive Neuroscience, Cardiff University Brain Research Imaging Centre, School of Psychology, and Neuroscience and Mental Health Research Institute, Cardiff University, CF10 3AT, United Kingdom, and.
authors.forename: Derek K
authors.initials: DK
authors.lastname: Jones
authors.affiliation: Wales Institute of Cognitive Neuroscience, Cardiff University Brain Research Imaging Centre, School of Psychology, and Neuroscience and Mental Health Research Institute, Cardiff University, CF10 3AT, United Kingdom, and.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Lawrence
authors.affiliation: Wales Institute of Cognitive Neuroscience, Cardiff University Brain Research Imaging Centre, School of Psychology, and Neuroscience and Mental Health Research Institute, Cardiff University, CF10 3AT, United Kingdom, and.
authors.forename: Kim S
authors.initials: KS
authors.lastname: Graham
mesh_terms: D001931:Brain Mapping; D004192:Discrimination, Psychological; D005145:Face / Q000033:anatomy & histology; D005260:Female; D020712:Fornix, Brain / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D007858:Learning; D008279:Magnetic Resonance Imaging; D008297:Male; D010364:Pattern Recognition, Visual; D055815:Young Adult
keywords: discrimination learning; fornix; hippocampus; scene discrimination; tractography