Figure 5.

Signal gradients influence expression of transcription factors that regulate cortical area patterning. At top, 4 transcription factors present in gradients that function in establishing cortical patterning in the mouse brain. At bottom left, a diagrammatic illustration of several cortical areas in a normal mouse. At bottom right, the patterning in “knock-out” (KO) mice in which various transcription factors are no longer expressed. Loss of these factors greatly alters the layout of cortical areas in the knock-out mice. V1 denotes visual cortex, A1 auditory cortex, S1 somatosensory cortex, and F/M motor cortex. A denotes anterior, P posterior, L lateral, M medial. Modified from O'Leary et al.²⁰.