Many of the higher functions, such as emotional reasoning, are located in the frontal lobe. However, memory and intuition may belong to the cerebrum.
It may be effective to realize that the brain is only as functional as our associations for its meaning. In other words, just 'knowing' what is supposed to work for highly functional people is not necessarily enough to make it work for individual writers. Identifying your own strengths and weaknesses is an important part of the process. What if for, example, (as I may have discovered recently about myself, possibly?) you have a much larger right brain than left brain? Or what if the back of your brain is more complex than the front of your brain? Or, what if individual areas in your brain function well, but without connectivity between the hemispheres? Or what if you're completely intelligent, but at the same time utterly insane?
All kinds of things can go wrong (or right) with the brain.
In general, the three types of brain are analogized to the lizard, the simian, and the human.
You want to think about what kinds of foods you can eat to improve your brain, such as fish skin and carbohydrates and leafy greens, and if there's any time where a particular area may have taken damage, that could suggest you focus on other strengths, or practice skills to help you recover.
The "human" brain is the frontal lobe (higher functions)
The simian brain is the cerebrum (instinct, memory, intuition)
The primitive brain is the cerebellum, below the cerebrum (balance, scale, fear, etc.)
In addition, several other specialized areas such as the amagdala and Broca's Area are responsible for specifically human memory and multi-lingualism.
So, if you want high quality writing, it's about the frontal lobe. If you want narrative fiction and animal instincts, then its about the cerebrum. If you want basic understanding of fear, then that's probably the cerebellum or amagdala combined with other things.
But, there is not necessarily a lot known about these areas until very recently. Scientists are still making guesses about the exact function of particular areas of the brain. Brains may even function very differently from person to person. But generally, a more complex, convoluted brain is smarter, and size only matters if it involves a relatively larger number of corruvulations. And the development of specific areas still matters too.