Specific Contributions of Ventromedial, Anterior Cingulate, and Lateral Prefrontal Cortex for Attentional Selection and Stimulus Valuation
(A,B) Reconstruction of a medial PFC (area 32, A), and a lateral PFC (area 46, B) recording site started from the 7T anatomical MR, which was obtained with (iodine based) visualization of electrode trajectories within the electrode grid placed inside the recording chamber. The outline of the cortical folding was sketched on the coronal MR slice to ease identification of areas and landmarks according to standard brain atlases, and to place the depth of the electrode tip (red dot in A and yellow dot in B) with custom MATLAB code. The electrode position was then placed into a standardized macaque brain available in the MR Caret software package . Caret allowed us to render the MR slice into a 3-D volume and to inflate the volume in order to finally cut (indicated as yellow line) the spherically inflated brain for representing it as 2-D flat map. (C) White lines on the flat map demarcate the principal sulcus (PS), the arcuate sulcus (ARC), and the cingulate sulcus (CS). The location of the FEF (frontal eye field) within the ARC is indicated by a green patch. Anatomical subdivisions in the fronto-cingulate cortex were visualized following the nomenclature from Barbas and Zikopoulus . The area 32 and area 46 recording sites are visualized throughout the panels by a red and a yellow dot, respectively. (D) Number of cells recorded across areas overlaid on the contour of areal subdivisions (in grey) from the flat map in (C). For each pixel in the map, we counted the recorded cells within 4 mm radius (in steps of 2 mm).