title: Dissociable contributions of the prefrontal cortex to hippocampus- and caudate nucleus-dependent virtual navigation strategies.
abstract: The hippocampus and the caudate nucleus are critical to spatial- and stimulus-response-based navigation strategies, respectively. The hippocampus and caudate nucleus are also known to be anatomically connected to various areas of the prefrontal cortex. However, little is known about the involvement of the prefrontal cortex in these processes. In the current study, we sought to identify the prefrontal areas involved in spatial and response learning. We used functional magnetic resonance imaging (fMRI) and voxel-based morphometry to compare the neural activity and grey matter density of spatial and response strategy users. Twenty-three healthy young adults were scanned in a 1.5 T MRI scanner while they engaged in the Concurrent Spatial Discrimination Learning Task, a virtual navigation task in which either a spatial or response strategy can be used. In addition to increased BOLD activity in the hippocampus, spatial strategy users showed increased BOLD activity and grey matter density in the ventral area of the medial prefrontal cortex, especially in the orbitofrontal cortex. On the other hand, response strategy users exhibited increased BOLD activity and grey matter density in the dorsal area of the medial prefrontal cortex. Given the prefrontal cortex's role in reward-guided decision-making, we discuss the possibility that the ventromedial prefrontal cortex, including the orbitofrontal cortex, supports spatial learning by encoding stimulus-reward associations, while the dorsomedial prefrontal cortex supports response learning by encoding action-reward associations.
authors.affiliation: Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Montreal, Quebec H4H 1R3, Canada. Electronic address: louisa.dahmani@mail.mcgill.ca.
authors.forename: Louisa
authors.initials: L
authors.lastname: Dahmani
authors.affiliation: Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Montreal, Quebec H4H 1R3, Canada.
authors.forename: Véronique D
authors.initials: VD
authors.lastname: Bohbot
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002421:Caudate Nucleus / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance; D065852:Spatial Memory / Q000502:physiology*; D065854:Spatial Navigation / Q000502:physiology*; D014584:User-Computer Interface; D055815:Young Adult
keywords: Hippocampus; Navigation strategies; Orbitofrontal cortex; Prefrontal cortex; Spatial memory; Stimulus–response; VBM; fMRI