Area Prostriata in the Human Brain

Area prostriata is a cortical area at the fundus of the calcarine sulcus, described anatomically in humans [ 1–5 ] and other primates [ 6–9 ]. It is lightly myelinated and lacks the clearly defined six-layer structure evident throughout the cerebral cortex, with a thinner layer 4 and thicker layer 2 [ 10 ], characteristic of limbic cortex [ 11 ]. In the marmoset and rhesus monkey, area prostriata has cortical connections with MT+ [ 12 ], the cingulate motor cortex [ 8 ], the auditory cortex [ 13 ], the orbitofrontal cortex, and the frontal polar cortices [ 14 ]. Here we use functional magnetic resonance together with a wide-field projection system to study its functional properties in humans. With population receptive field mapping [ 15 ], we show that area prostriata has a complete representation of the visual field, clearly distinct from the adjacent area V1. As in the marmoset, the caudal-dorsal border of human prostriata—abutting V1—represents the far peripheral visual field, with eccentricities decreasing toward its rostral boundary. Area prostriata responds strongly to very fast motion, greater than 500°/s. The functional properties of area prostriata suggest that it may serve to alert the brain quickly to fast visual events, particularly in the peripheral visual field.