This comes from me noticing that my mind seems to be splitup into 5-6 different sections, that do different sort of thinking, and do different sorts of decision making processes. These sections do not fit the MBTI system, although some of the divisions do fit closely with, say "Ti", a some do not.
the way my mind seems to divide up:
Various completely unconscious pieces: These are pretty much the parts of my mind that control movement, sense things, etc. when I decide to do something. (For example, when I decide to turn on the computer and type something, the more conscious parts of my mind are not the ones telling fingers to move to a certain place, legs to go up and down, etc., they just sort of happen. Similarily, if doing calculus, I don't go through the same thought process of, say "integral of 1/x = lnx" all the time, I simply notice the notation and write it down.)
Fear lobe: this is the section that tends to be afraid of things, and is the source of a lot of procrastination, fear of new things, inhibitions, etc. It also prefers doing already established habits, and sticking to doing the same thing every day. It's also mainly a section that I don't see in action, but it does seem that this part of my mind will take control and prevent some decision made by another section from occurring, or it provides a lot of resistance to decisions from another section of my mind.
Imagination: This is exactly what it says. This part of my mind tends to count the chickens before they hatch, and come up with all sorts of new ideas for things (Many of which don't get carried out, but they are there just the same.)
Logic/ambition: This part of my mind is the one that makes decisions about what I should be doing, plans them out, and decides logically whether things will or won't work. This is a part of my mind that I try to actually listen to, as it gets things right more often than not, making decisions that are almost always better than the fear lobe and optimism sections, but it doesn't have the ability to take over and actually force me to do things. (It is quite common for me to decide to do something with all intention of doing it, than suddenly not do it, or only get myself to do it with a lot of effort, thanks to some sudden resistance that appears.)
Pattern section: this is the section that just watches things happen and finds patterns in it. It if the "gut instinct' section that manages to figure out a lot about people that the other sections of my mind don't notice. It's also the section that notices oddities in math, science, art, how my mind works, etc. and figures them out.
Optimism: This section is the one that assumes, without relying on logic, that things will go well. It also seem to be the most emotion based section, and the section that encourages the most risk taking.
Conscious mind: This is "me", and is also the section that gathers together input from the other sections and, most of the time, decides what to do. (Though sometimes fear lobe or optimism make the decisions, and sometimes I run on auto pilot.) A lot of intereactions consists of "me" trying to force myself to do something that logic/ambition came up with, that fear lobe doesn't want to do.
Some of these possibly relate to brain structures ("me" is the frontal section, limbic system may be the source of fear lobe and.or optimism.), though I haven't heard enough about how the brain is divided up to be sure.