21.   If Rupert Murdoch or Bill Gates started talking about tinkering with your visual cortex, it would sound chilling.

22.   Parts of the visual cortex switch dominance every few seconds, he said, whereas parts of the frontal lobes cycle every couple hours.

23.   Over time, the potassium spread from the visual cortex to the pain-controlling neurons in the meninges.

24.   The message is received by the visual cortex.

25.   The path starts with the primary visual cortex.

26.   The primary visual cortex is the area in the back of the head where information from the eyes first reaches the cortex.

27.   The rewired map was less orderly than the maps found in normal visual cortex, Sur said, but looked as if it might be functional.

28.   The thalamus then sends signals to the visual cortex for full analysis.

29.   Then there is that disorienting shock to the visual cortex as you step from the shadow of the tunnel into the dazzling sunshine of the stands.

30.   There is evidence, too, that melody stimulates parts of the visual cortex, as if a picture were being presented to the brain.