Automatized clustering and functional geometry of human parietofrontal networks for language, space, and number.
Human functional MRI studies frequently reveal the joint activation of parietal and of lateral and mesial frontal areas during various cognitive tasks. To analyze the geometrical organization of those networks, we used an automatized clustering algorithm that parcels out sets of areas based on their similar profile of task-related activations or deactivations. This algorithm allowed us to reanalyze published fMRI data (Simon, O., Mangin, J.F., Cohen, L., Le Bihan, D., Dehaene, S., 2002. Topographical layout of hand, eye, calculation, and language-related areas in the human parietal lobe. Neuron 33, 475-487) and to reproduce the previously observed geometrical organization of activations for saccades, attention, grasping, pointing, calculation, and language processing in the parietal lobe. Further, we show that this organization extends to lateral and mesial prefrontal regions. Relative to the parietal lobe, the prefrontal functional geometry is characterized by a partially symmetrical anteroposterior ordering of activations, a decreased representation of effector-specific tasks, and a greater emphasis on higher cognitive functions of attention, higher-order spatial representation, calculation, and language. Anatomically, our results in humans are closely homologous to the known connectivity of parietal and frontal regions in the macaque monkey.
Simon
Olivier
O
Service hospitalier Frédéric Joliot, CEA/DSV, Orsay, France.
Kherif
Ferath
F
Flandin
Guillaume
G
Poline
Jean-Baptiste
JB
Rivière
Denis
D
Mangin
Jean-François
JF
Le Bihan
Denis
D
Dehaene
Stanislas
S
D000818:Animals; D001288:Attention / Q000502:physiology; D016000:Cluster Analysis; D005625:Frontal Lobe / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D007802:Language; D008251:Macaca; D009415:Nerve Net / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D012438:Saccades / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*