title: The organization of dorsal frontal cortex in humans and macaques.
abstract: The human dorsal frontal cortex has been associated with the most sophisticated aspects of cognition, including those that are thought to be especially refined in humans. Here we used diffusion-weighted magnetic resonance imaging (DW-MRI) and functional MRI (fMRI) in humans and macaques to infer and compare the organization of dorsal frontal cortex in the two species. Using DW-MRI tractography-based parcellation, we identified 10 dorsal frontal regions lying between the human inferior frontal sulcus and cingulate cortex. Patterns of functional coupling between each area and the rest of the brain were then estimated with fMRI and compared with functional coupling patterns in macaques. Areas in human medial frontal cortex, including areas associated with high-level social cognitive processes such as theory of mind, showed a surprising degree of similarity in their functional coupling patterns with the frontal pole, medial prefrontal, and dorsal prefrontal convexity in the macaque. We failed to find evidence for "new" regions in human medial frontal cortex. On the lateral surface, comparison of functional coupling patterns suggested correspondences in anatomical organization distinct from those that are widely assumed. A human region sometimes referred to as lateral frontal pole more closely resembled area 46, rather than the frontal pole, of the macaque. Overall the pattern of results suggest important similarities in frontal cortex organization in humans and other primates, even in the case of regions thought to carry out uniquely human functions. The patterns of interspecies correspondences are not, however, always those that are widely assumed.
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom. jerome.sallet@psy.ox.ac.uk
authors.forename: Jérôme
authors.initials: J
authors.lastname: Sallet
authors.forename: Rogier B
authors.initials: RB
authors.lastname: Mars
authors.forename: MaryAnn P
authors.initials: MP
authors.lastname: Noonan
authors.forename: Franz-Xaver
authors.initials: FX
authors.lastname: Neubert
authors.forename: Saad
authors.initials: S
authors.lastname: Jbabdi
authors.forename: Jill X
authors.initials: JX
authors.lastname: O'Reilly
authors.forename: Nicola
authors.initials: N
authors.lastname: Filippini
authors.forename: Adam G
authors.initials: AG
authors.lastname: Thomas
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Rushworth
mesh_terms: D000328:Adult; D000717:Anatomy, Comparative; D000818:Animals; D001931:Brain Mapping / Q000379:methods*; D003071:Cognition; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006179:Gyrus Cinguli / Q000033:anatomy & histology*; D006801:Humans; D008253:Macaca mulatta / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D017397:Prefrontal Cortex / Q000033:anatomy & histology*; D055815:Young Adult