Mind on the Brain

It is the time of the semester when thoughts turn to the brain, because many psychology texts (rightly!) make the brain the focus of either the second or third chapter. In preparation for these discussions, I try to anticipate what myths my students believe that I might need to debunk.

  • The brain does not exist only to cool the blood, as Aristotle once believed. Actually, I have to tell students this myth, and who Aristotle was. But it never hurts to be prepared for a student with an unconventional, purely classical philosophy education. Should that ever happen, I will quote satirist Will Cuppy: “This is true only of certain persons“.
  • There are not more neurons in the brain than there are stars in the galaxy. Our best estimate is 86 billion neurons in a brain. That’s quite a bit – if neurons were seconds, that would be 2,725 years in a brain – but still less than a quarter the stars in the Milky Way. And no, we don’t count either of those by hand; we count a small section and extrapolate up.
  • There are not more connections between neurons than there are atoms in the universe; that’s a logical impossibility.  However, it is reasonable to say there are more connections between neurons than there are stars in our galaxy – estimates of the number of connections per neuron vary widely, but it’s definitely more than the 4-5 needed to pass 400 billion stars.
  • You do not have a “left brain” or “right brain”.  Even the claim that language is in the left hemisphere is only true for perhaps 90% of the population – and if language has such natural variability, do you really think analytical intelligence and artistic creativity are so simple? Researchers have actually conducted studies specifically to debunk the idea that people have one dominant hemisphere. Intelligence seems to rely on connections between many regions in both halves of the brain, and creativity likewise wants both halves.
  • Some of the classic “truths” about the brain, dating back to the 1800s and repeated in textbooks today, are not true, or at least not so simply true as people think. Consider the “truth” that damage to a region of the brain called Broca’s area produces Broca’s aphasia, the inability to speak words. In fact, there must be damage to nearby regions as well to produce Broca’s aphasia; damage to Broca’s area alone won’t do it.
  • The brain is not a collection of specialized regions that do one thing, and one thing only. It’s a tempting idea that dates back to phrenology, and it’s true that neurons organize themselves into groups that take on similar roles. For most of the brain, however, suggesting that one region has one specific job is a gross oversimplification. There is an ongoing “battle for Broca’s region” because that small portion of the brain turns out to be involved in many more tasks than just speaking. Another region of the brain, the amygdala, is popularly known as the “fear center”, but this is another oversimplification that cannot hope to fully describe how the size of your amygdala predicts the size of your social network.

Most of these myths exist because we are trying to understand our brains, with simultaneous competing urges to be awed by our  brains’ complexity (more neurons than stars! and atoms!) and to have them be simple enough for us to understand (oh, the amygdala is fear, Broca’s area is speaking, the fusiform gyrus is faces….).

xkcd’s “Debugger”

I dispel the myths – or try to; they can be incredibly sticky – because I want my students to realize that our brains are complex, and we don’t really understand how they work, but that isn’t a problem. We don’t need to know the precise molecular details of how my hard drive works to enjoy life in the 21st century, and we don’t have to “solve” the brain to lead productive lives or to help people.

In fact, knowing that the puzzle of the brain will lend a delightful sense of mystery to the lives of neuroscientists for generations to come makes the universe seem a more fascinating and delightful place to live.

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