Measuring the Mind

The are hundreds of ways in which we measure varying parts and functions of the human body. With almost all of them, we can say, "because this is happening, these other things are happening." While that was not very eloquently stated, the point of it is describe how we are not exactly sure what the measurements of the brain mean. To elucidate the point further, take heart rate for example. We can measure the heart rate and state that a higher rate means that the heart is pumping blood more quickly, while a slower heart rate means that the heart is pumping blood more slowly. There are many different techniques to measure the activity of the brain, but what does each of them say about what is occurring in the mind?

There are really two different ways to go about measuring the brain, structurally and functionally. To measure the brain structurally, there are a few different techniques including MRI and CAT/CT scans. MRI uses magnetic fields to detect radiation from certain molecules which are present at varying levels in different tissues. The fluid contrast between structures in the brain can be visualized and is helpful in viewing brain neuroanatomy. A CAT/CT scan on the other hand uses x-rays to produce an image of the brain. While these measures of the brain are interesting and can demonstrate information about the structures or abnormalities of the brain itself, it does not show us how the brain is actually functioning.

Functional imaging of the brain does help to elucidate how the brain is functioning. To view images of activated brain regions by detecting the indirect effects of neural activity on local blood volume, flow, and oxygen saturation, you can use fMRI. To measure brain activity, you can you EEG. However, what are these actually telling us? A rise in blood volume, meaning greater activity, meaning that the brain area had more neural activation at the time that the measurement was taken as compared to the baseline measurement. How do we know that the baseline measurement is actually an average measure of the brain activity? How do we know that a change from baseline necessarrily means a correlation between that brain area and the task or the measurement that is occuring. The difference in the wiring of people's minds also has to play apart in how different people accomplish the same task. There seems to be inherent problems in using these techniques and observing the behavioral outputs as correlates. I believe that an effort to lessen the time scale of these measurements, as well as the use of hybrid models, in which multiple techniques are tested against eachother will be helpful in actually pinpointing what is occuring in the brain.

This summer as I start my Ph. D. program and venture into the world of these functional scans, I hope to keep on ongoing dialogue about what these scans are actually telling us. I remember a story last year, in which statistical significance was found in a "noise" and that that raises questions of the validity of using these scans to draw some conclusions. It will be interesting to always ask about the reliability of the test. While I think that it is a very powerful tool, it is one that needs refining and also one that needs to be used with other methods. As of now I am somewhat apprenhensive about what the scans are actually telling us, but only time will tell.

The brain controls all that we do through the communication of neurons, the changes in firing rates, the changes in the strengths of connections between neurons, and the release of chemical messengers, and hormones all change how are brain functions and what it is trying to accomplish. But what do the changes mean? A rise in a neurotransmitter here, an increase in firing there. These changes are occurring on a time scale of milliseconds, while our measurements are occurring on a much different time scale. While the brain is accoplishing all these physiological activities it is important to remember what is arising from these activities, the mind. We must not forget that while we may be able to measure what the brain is doing, we still have much further to go before we measure what is occuring in the mind. Through contemplation and self reflection we can investigate our own minds. However, this topic can have a post of its own at a later time.