title: A Putative Multiple-Demand System in the Macaque Brain.
abstract: In humans, cognitively demanding tasks of many types recruit common frontoparietal brain areas. Pervasive activation of this "multiple-demand" (MD) network suggests a core function in supporting goal-oriented behavior. A similar network might therefore be predicted in nonhuman primates that readily perform similar tasks after training. However, an MD network in nonhuman primates has not been described. Single-cell recordings from macaque frontal and parietal cortex show some similar properties to human MD fMRI responses (e.g., adaptive coding of task-relevant information). Invasive recordings, however, come from limited prespecified locations, so they do not delineate a macaque homolog of the MD system and their positioning could benefit from knowledge of where MD foci lie. Challenges of scanning behaving animals mean that few macaque fMRI studies specifically contrast levels of cognitive demand, so we sought to identify a macaque counterpart to the human MD system using fMRI connectivity in 35 rhesus macaques. Putative macaque MD regions, mapped from frontoparietal MD regions defined in humans, were found to be functionally connected under anesthesia. To further refine these regions, an iterative process was used to maximize their connectivity cross-validated across animals. Finally, whole-brain connectivity analyses identified voxels that were robustly connected to MD regions, revealing seven clusters across frontoparietal and insular cortex comparable to human MD regions and one unexpected cluster in the lateral fissure. The proposed macaque MD regions can be used to guide future electrophysiological investigation of MD neural coding and in task-based fMRI to test predictions of similar functional properties to human MD cortex.
  
  
  
  In humans, a frontoparietal "multiple-demand" (MD) brain network is recruited during a wide range of cognitively demanding tasks. Because this suggests a fundamental function, one might expect a similar network to exist in nonhuman primates, but this remains controversial. Here, we sought to identify a macaque counterpart to the human MD system using fMRI connectivity. Putative macaque MD regions were functionally connected under anesthesia and were further refined by iterative optimization. The result is a network including lateral frontal, dorsomedial frontal, and insular and inferior parietal regions closely similar to the human counterpart. The proposed macaque MD regions can be useful in guiding electrophysiological recordings or in task-based fMRI to test predictions of similar functional properties to human MD cortex.
authors.affiliation: Medical Research Council Cognition and Brain Sciences Unit, Cambridge CB2 7EF, United Kingdom, and Daniel.mitchell@mrc-cbu.cam.ac.uk.
authors.forename: Daniel J
authors.identifier: 0000-0001-8729-3886
authors.initials: DJ
authors.lastname: Mitchell
authors.affiliation: Medical Research Council Cognition and Brain Sciences Unit, Cambridge CB2 7EF, United Kingdom, and Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom.
authors.forename: Andrew H
authors.identifier: 0000-0001-8420-4622
authors.initials: AH
authors.lastname: Bell
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom.
authors.forename: Mark J
authors.identifier: 0000-0001-7455-8486
authors.initials: MJ
authors.lastname: Buckley
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom.
authors.forename: Anna S
authors.identifier: 0000-0001-8996-1067
authors.initials: AS
authors.lastname: Mitchell
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom.
authors.forename: Jerome
authors.initials: J
authors.lastname: Sallet
authors.affiliation: Medical Research Council Cognition and Brain Sciences Unit, Cambridge CB2 7EF, United Kingdom, and Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom.
authors.forename: John
authors.identifier: 0000-0002-9695-2764
authors.initials: J
authors.lastname: Duncan
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000502:physiology; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000502:physiology*
keywords: connectivity; fMRI; frontoparietal; macaque; multiple demand; resting state