Why do I have scar tissue on the brain?

Who told you that? "Scar" is only defined as abnormal skin, not internal tissues. Scar tissue actually requires less oxygen than normal skin, so taking vitamin E can have a beneficial effect. It is sold in drug stores for that purpose. Get "Pure Vitamin E Skin Beauty Oil" at the cosmetics counter. Be sure it says "Pure". You can also use capsules by poking a hole with a pin and squeezing the oil out. Vitamin E has to soak in, so put it on when you can leave the skin bare for a while.