Learn why biology is not destiny.

Tuesday, March 13, 2007


Of Mice and Memory But Still Biodetermism

Let's assume there is solid research that shows after mice exercise we find more blood flow to a region of their brain called the "dentate gyrus," which is also the name given to a similar region of the human brain associated with what's been called age-related memory loss that can start as early as middle age. The scientific study on mice has two groups: Group A exercises and Group B does not exercise. All other extraneous variables are kept consistent among the two groups of mice (such as food, living conditions, exposure to light and ability to sleep, etc.) so that we can confidently conclude the factors we are isolating are exercize (the independent variable) and brain cell growth (the dependant variable). Let's also assume we do a brain cell count and it turns out the group of mice that exercised had more brain cells compared to the other group. We conclude exercise must play some important role in developing "brainpower" for memory and learning.

Next, researchers move to the human cohort because they really care more about how learning and memory works with humans. They do a related study in which two groups of human subjects either exercise or don't exercise, but since we can't sample their brain tissue for a neuron count (still presently considered unethical thank God) we rely on our technology for indirect evidence of brain stimulation. Magnetic resonance imagery (MRI) reveals the part of the human brain we also call the "dentate gyrus" to be receiving more blood flow in the group that exercised compared to the group that did not, and this is right in line with our mice study. Time to hit the press and publish our study, and that's exactly what the National Academy of Sciences did. The public was informed here:
and here:

Both articles are entitled "Study Shows Why Exercise Boosts Brainpower." Curiously, no name of the journalist(s) is given.

A Case of Biodeterminism

Right from the onset of this article the journalist proclaims "Exercise boosts brainpower," which I would agree with to some degree, only HOW does this occur according to our biodeterministic writer?-- "by building new brain cells in a brain region linked with memory and memory loss." This statement assumes memory for humans is a simple matter of how many brain cells you have, which is utter nonsense. Memory is just as much a matter of how to retrieve the information as it is whether there are enough neurons in the brain to store it. Apparently, even the researchers optimistically conclude: "Our next step is to identify the exercise regimen that is most beneficial to improve cognition and reduce normal memory loss, so that physicians may be able to prescribe specific types of exercise to improve memory." Unbelievable.

Problem 1: Exercise increases blood flow to just about ALL regions of the body, not just the "dentate gyrus" in the brain. Increased blood flow to a region of the brain means this region is being used more than other regions, but the rest of the brain is still working in addition to the dentate gyrus.

Problem 2: No direct evidence of brain cell growth. Increased blood flow to any region of the brain does not necessarily mean more brain cell growth. You can't count brain cells using an MRI. However, the journalist writes, "They of course could not dissect the brains of people to see if new neurons grew, but they could use MRI to have a peek," which is pretty close to a lie misleading the public about what our magnetic imaging tests can and cannot do.

Problem 3: Although it may be tempting to do so because of the behavior of some people contributing to a "rat race" among humans, overgeneralizing from the cognition of mice to the cognition of human beings is generally very bad science.

Problem 4: The assumption that more brain cells = "smarter." You might as well assume a person who eats is smarter because you need food and the energy it provides to create new brain cells. Since when does the number of brain cells a person has indicate how well his or her memory works? There would obviously be a threshold at which not having enough brain cells impairs memory, but its not the typical case scenario as is being reported by this study and as evidenced by the participants who had no obvious brain impairment. What do the researchers actually find? According to the article, "Exercise generated blood flow to the dentate gyrus of the people, and the more fit a person got, the more blood flow the MRI detected." There's no brain cell counts and no memory or learning tests being given that shows one group outperforms the other. We are still in the region of pure biology here. As absurd as it may sound, nobody even tested the mice to see if after the exercise they became smarter in any way. Don't ask me what valid test of cognition you can give to a mouse, especially if you think it can be generalized to human cognition.

In case you can't see it, here's a hint of the underlying biodeterminism within the article typical of our culture: The assumption that the will to learn plays no role in learning for humans. Just think of the joy it would bring to Americans to be told all you need to do is exercize and you'll get "smarter." You can prevent age-related memory loss by exercising because your dentate gyrus will receive more blood flow than if you didn't exercise. Hurray.

Here's the blatant biodeterminism: What does the journalist want us to believe?--a new breakthrough in our science of cognitive psychology as it pertains to some relationship between brain cell growth, exercise, and learning. There is no real breakthrough.

Reality: What do we actually now know about human beings as it pertains to this study?--very little if anything at all, except of course a predictably growing trend toward biodetermism. Biodeterminists want learning and memory in humans to be that predictable and that automatic, and capitalists are ready to follow. I can't wait to see the TV commercials for the new drug Gyrutus that stimulates the dentate gyrus region of the brain giving you more brainpower to compete with the the other rats of the rat race. Side effects include making the pharmaceutical industry very wealthy. This is where our concept of learning is headed. Poor memory? Have you had your dentate gyrus examined?

Don't get me wrong. Exercise is important for many health-related reasons. But when it comes to the need for exercise to stimulate blood flow to the dentate gyrus? Don't get me started. It is getting increasingly more difficult in our society to understand human learning, memory, and behavior is not just a function of the brain. If this doesn't make sense to you, perhaps you need to understand how our culture of biodeterminism is reducing just about everything down to biological constituents.

Help stop biodeterminism by learning what it is! Read about it here:

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