Primitive survival instincts like fear are processed in a part of the brain called the limbic system. This includes the amygdala, a region that processes emotion, and the hippocampus, a region involved in reliving traumatic memories.
Brain scan studies have shown that overactivity in these two regions returns to normal after a course of CBT in people with phobias.
What's more, studies have found that CBT can also change the prefrontal cortex, the part of the brain responsible for higher-level thinking.
So it seems that CBT might be able to make real, physical changes to both our "emotional brain" (instincts) and our "logical brain" (thoughts).
Intriguingly, similar patterns of brain changes have been seen with CBT and with drug treatments, suggesting that psychotherapies and medications might work on the brain in parallel ways