What this is
The two faces are a line map of the classic Brodmann scheme, descending from Brodmann’s own 1909 figures: every area outlined and numbered, nothing drawn beneath. Tap an area and it fills in its lobe’s colour on the face that shows it, and what it does appears beside the map; tap it again to let it go, and pinch a face to look closer. Anterior is on the left in the external view and, as the scheme is conventionally drawn, on the right in the internal one. The drawing is a schematic; where each area actually sits in a real head, with the atlas’s own boundaries, is what the brain shows: the area lit on the MNI152 brain in 3D, which turns under a finger, and in the axial, coronal and sagittal slices through it, picked on the bar along the brain’s top, where Slice cuts into the 3D view; always on show beside the map on an iPad or a computer, beside the faces on a phone held sideways, and raised over them by the bar’s 3D tab on a phone upright. Brodmann Areas diagram adapted with permission from IFEN – Institute for EEG-Neurofeedback / Neurofeedback Academy.
Brodmann numbered the cortex in 1909 by how its cells are layered, not by what it does, which is why the numbers wander about the brain and why several of his 52 have no agreed human counterpart. The 41 here are those the atlas labels; 12, 31 and 33 are drawn dashed because the atlas does not carry them, and 48, the peri-Sylvian and insular territory, is buried and reaches neither face. Each area is bilateral: Brodmann described cortical types, not hemispheres, so where a function is strongly one-sided the note says so. The boundaries are an approximation to begin with: they were drawn from a handful of post-mortem brains, and no two people’s cortex is folded the same way. Read a boundary as a neighbourhood, not a border. Educational, not diagnostic.
Brodmann diagram adapted with permission from IFEN. Area data from the Brodmann atlas in MRIcron (BSD), on the MNI152 template, the brain rendered with NiiVue (Rorden lab).
Visual Neuroscience