The genetic correlations for the frontal pole seed point displayed a clear A-P division, with a boundary separating positive and negative genetic correlations approximately PLX3397 chemical structure aligned with the central sulcus (see Figure S1 available

online for anatomical location), a border between motor and sensory areas (Figure 1A). The positive genetic correlations in Figure 1A show that genetic factors associated with expansion of the surface area around the seed point (indicated by a black dot) are also associated with expansion of other frontal regions (indicated by the red-to-yellow color scale). The negative genetic correlations in the posterior regions show that genetic influences associated with areal expansion of the frontal pole seed region cause relative areal contraction in posterior regions (indicated by the blue-to-cyan color scale). Findings from several mouse studies using experimental inhibition or overexpression of specific genes support the antagonistic A-P genetic effects. For instance,

the transcription factor Pax6 has anterior-high to posterior-low gradients of gene expression and promotes frontal/motor areal expansion (Bishop et al., 2000). Another transcription factor, Emx2, is expressed in an opposite gradient (Bishop et al., 2000 and Mallamaci et al., 2000). Furthermore, Pax6 and Emx2 mutually suppress MK 2206 one another’s expression, regulating areal expansion. In addition to the A-P division described above (Figure 1A),

positive genetic correlations were observed around the S1 seed region in the primary sensory and superior parietal cortices and partially in the primary motor cortex (Figure 1B). Genetic correlations with S1 resulted in a primarily postcentral division, with correlations becoming negative anterior to the precentral sulcus and roughly posterior and inferior to the parietal lobe. Area patterning for the anterior temporal pole seed point showed positive genetic correlations primarily in the temporal lobes, including the presumed human homolog of mouse A1, with negative genetic correlations in the rostral and caudal regions (Figure 1C). For the V1 seed region, we observed strong positive genetic correlations covering the occipital cortex. The correlations extended partially to the superior Oxygenase parietal cortex, which was suggestive of the dorsal stream of the visual system (Kandel et al., 2000). Genetic correlations with the V1 seed region were negative for anterior temporal and frontal cortices (Figure 1D). The boundaries of the genetic correlations corresponded substantially to known anatomical landmarks (e.g., major sulci such as the central sulcus). However, some boundaries did not match any traditional anatomical divisions. The observed patterns may reflect the combinatory actions of many other molecular gradients, including D-V and medial-lateral gradients in addition to A-P gradients.