It seems odd to me that even when I discussed the orientation at a conference on personality type there seemed to be quite a bit of disbelief that the functions could be located in specific quadrants of the brain. I don’t know about some other people but it makes sense to me that the "sensing" function should reside in an area of the brain with three "sensory lobes" and that subjective interpretation should also reside in an analogous structure. Additionally it certainly makes sense to me that the most "abstract" and most distinctly human specific functions should reside in parts of the brain (frontal lobes) that are most uniquely developed in humans and least likely found in other animals. I think the confusion has been caused by imprecise testing and insufficient understanding of the complexity of thought. For localizing function it is necessary to determine the most discrete forms of data to test. (See pattern recognition and matrix IQ testing.)

The Physiology of Jung’s Four Functions & Their Organization
By Katherine Benziger, Ph.D., © March 1998; September 1999
“With respect to the human cortex, functional specialization is said to exist in that: (1) the cortex is clearly divided into four almost equal elements, in that each hemisphere or half is further divided by a central or rondalic fissure which separates the frontal lobe on each side from posterior portion of the hemisphere, today known as the posterior cortical convexity; (2) each of these four areas can be shown function differently; and (3) each contributes differently based on its unique specialized capabilities.”

“Significantly, among neuro-physiologists there exists some disagreement about functional specialization. Some researchers argue, when looking from a particular perspective, that the brain is also highly integrated and seemingly at times redundant. Auditory information is processed in many areas. Indeed, even music is processed in many areas. Moreover, language in some persons can be shown to involve all four regions of the cortex. The key to this discussion is that the cortex is both specialized and integrated, much as an assembly-line or a computer.”
- Haier, Richard. Cortical Glucose Metabolic Rate Correlates of Abstract Reasoning and Intelligence, Studied with Positron Emission, by Haier et al. unpublished paper from January 1988.
- Haier, Richard. The Study of Personality With Positron Emission Tomography in Personality Dimensions & Arousal, ed. by Jan Stvelan & Hans J. Eyesenck. Plenum Publishing Company, 1987.

    I would like to read Dr. Haier’s original research. While I find Dr. Benziger’s conclusions extremely informative I couldn’t help noticing that she used the word "most" in the following statement,

“Moreover, Haier’s research has shown repeatedly that most people have one area which enjoys a much lower level of electrical resistance – using only one one-hundredth the oxygen / energy - when compared with all the other areas of that person’s cortex.”

What does that mean? Here is a bit of intuitive exploration I conveyed to a friend on the matter. You can skip it if you prefer, as it is just speculative rambling.