Figure 6.

Here a schematic cross-section of the arcuate fasciculus is delineated. On the left (A) the orientation of the fasciculus are defined by three axes anterior–posterior, dorsal–ventral and lateral–medial. The second to the left scheme (B) represents a chaotic distribution of axonal fibres, with several possible arbitrary positions of the pioneer axon, whereas the increased red colour typifies older axonal pathways. The second to the right scheme (C) stands for a possible alternative order driven by a laterally oriented axonal architecture. At the right scheme (D), the proposed architecture due to the maturation of the fasciculus is outlined as suggested by the Pioneer Axon Thesis – thus, the pioneer axon is located medially.