Chemistry: Matter and ChangeChapter 1: Introduction to ChemistryIn the NewsGhosts or Brain Chemistry?April 2005One of the most powerful insights modern science have given us into ourselves is that our very thoughts are somehow connected to the chemistry of our brains. Scientists won't know the exact details of this connection for many years yet, but we get the general picture: certain chemicals in the brain are responsible for certain kinds of thinking. This realization leads to all sorts of interesting possibilities. Just this year, for example, a neurologist named Peter Brugger, who works at the University Hospital in Zurich, Switzerland, became curious as to whether people who believe in paranormal events have a different brain chemistry than those who don't. “Paranormal events” means ghosts, magic, and general supernatural happenings. Scientists dismiss claims for paranormal events because there is no evidence for them. Still, a great many people report seeing ghosts, for example, every year. Why is this? Peter Brugger suspected the difference between people who think they experience paranormal events and people who don't may be in those chemicals. Ghost in the Machine To test his idea, Brugger gathered forty volunteers. Twenty of them were “believers”--people who, by their own description, believe in paranormal events. The other twenty were “skeptics”--people who, by their own description, didn't believe in anything paranormal. Both groups sat in front of a machine that flashed images of people's faces as well as scrambled images that didn't have faces in them. The volunteers had to decide whether they had seen a face or not. A similar test was run with scrambled words. The idea was that “believers” might be more likely to see a face when there wasn't one there. In other words, something about their brain chemistry might be causing them to interpret random information in a meaningful way. That could explain why some people see ghosts where others just see shadows, or why some people see magic where others just see a coincidence. Sure enough, when the results were in, the “believers” group claimed to have seen more faces than were there, while the “skeptics” saw fewer than were there. That's interesting, because neither group was seeing reality: one shot high and one shot low. But wait--it gets even better. Now for the Brain Chemistry If chemicals underlie our thoughts, then you should be able to change the way people think by changing the chemicals in their brains. To test this, Brugger gave his volunteers a dose of a drug called “L-dopa,” which increases the levels of a brain chemical called “dopamine,” and had them do the test again. Did their reactions change? They sure did--the skeptics who had taken L-dopa, and therefore briefly had more dopamine in their brains, now reported seeing more faces and words than they had before! The believers stayed about the same. What was going on? Making Believers Out of Skeptics One way to interpret Brugger's data is to say that the more dopamine you have in your brain, the more likely you are to see patterns when there aren't any. As a result, high-dopamine brains will belong to people who believe in supernatural things and low-dopamine brains to people who don't. Giving extra dopamine to the skeptics briefly made them more like believers. The believers didn't change because they already have high levels of dopamine in their brains. If this is true, why would mother nature make us this way? That's an excellent question, and more research will need to be done to figure it out. We can take a guess, though. Being able to recognize patterns in nature is an important part of human survival. We evolved into the kinds of brains we have over many millennia, and the ability to spot an animal hiding in a bush is one we needed all that time. If the chemical dopamine helps us spot those patterns, then you would expect us to have a lot of it in our brains. On the other hand, if you have *so much* dopamine that you see patterns when there aren't any, you can make mistakes. Humans who were *forever* seeing ghosts and goblins--and therefore missing the real animals--wouldn't have lasted long. It's probably no coincidence that human brains today are close to the line between believing silly things and refusing to believe anything at all. Activity: Take a poll of your friends. How many believe in ghosts? (Make sure you ask them individually instead of as a group so that some people's answers don't influence other people's answers.) How many have actually seen a ghost? Do you see any pattern among your friends--that is, do certain people tend to believe in paranormal events more than other people? New Scientist: Neuroscience Center, Zurich: Team Dopamine Home Page: |  |
