Figure 5.

Vascular unit model proposed by Harel et al.80 (reproduced with permission from Frontiers in Neuroenergetics). The (a) circular nature of the vascular organization is shown in a cross‐section showing the venous units and (b) their arterial rings; a principle cortical vein (blue) is surrounded by several penetrating arteries (red). (c) Vessel classification maps in a tangential section in cat visual cortex, derived from the magnetic resonance imaging data.