Quirks & Quarks

Scientists could look in your brain to determine your intelligence

Brain 'entropy' - the number of different states it can enter - correlates with IQ scores
Scientists have found that the number of different 'brain states' you can enter is correlated with intelligence

Researchers have used functional MRI scans to measure the variability of brains over time - what they call "brain entropy" and found that high entropy is connected with high IQ scores. This suggests that we might be a step closer to understanding what it is about that makes brains more or less intelligent.

Canadian researcher Dr. Glenn Saxe, a professor in the Department of Child and Adolescent Psychiatry at the New York University School of Medicine, and his colleagues, studied fMRI scans of nearly 900 people. They measured how many different and distinct neural states - essentially different ways the brain could be active - that people's brains entered while they were in the scanner.  This gave them a measure of brain entropy, and by comparing it to IQ scores, they found that more brain entropy correlated with higher IQ scores, and lower entropy with lower scores.

Read a transcript of this interview below. The transcript has been edited for length and clarity.

Bob McDonald: What is it about the brain that you were trying to explore in this study.

Dr. Glenn Saxe:  I think the interesting thing is how does a person's brain understand its world? The brain is confronted with sensations all the time, and the information the brain receives is constantly changing.  And intelligence really is the way the brain make sense of its world when there's no way of predicting what information may come in.

When you think of it that way, in order to flexibly understand and predict a hugely unpredictable world, you have to have a lot of different neuronal configurations, or what we call brain states. How many states does a brain have access to in a given moment, so that it can deploy them to understand what might come in. That's called entropy.

BM:  So the number of ways that a brain can be.

GS:  Exactly.

BM:  Well how did you study this in your work?

GS:  We could do that with functional magnetic resonance images.  We could look at the smallest unit of an image which is called the voxel - it's a 3 millimetre cube of a functional brain scan.  And we can watch over time and look at how many states it has access to in any moment and where in the brain those states may be. 

BM:  I'm thinking of the phrase here "the prepared mind." If the brain can be in a lot of different states then if anything comes along I'm ready for that, I can I can take this on.  If I'm only in one state of mind I can only deal with one thing. 

GS:  Exactly.  And that's why we looked at what's called resting state. We weren't asking people to do tasks, we were asking them to just sit in the scanner think of whatever is on their mind.  So they're ready for whatever might come. What happened then is there were clusters of voxels that related to intelligence and we looked at where exactly in the brain those clusters.  Everywhere we looked, the higher entropy,  the higher the intelligence.

fMRI scanners can measure brain activity (Alexandra Tinnermann and Tim Dretzler/University Medical Center Hamburg-Eppendorf)
BM:  So I'm just trying to picture that. The MRI scanner looked at brain activity and so you were using that to see how many states the brain could be in, and whether it was in a lot or a few. This is entropy - high entropy or low low entropy.

GS:  Yes, we're tracking how many states that brain has access to.

BM:    So if you weren't testing them for anything how did you relate their brain activity to intelligence?

GS:    After they were in the scanner they took IQ tests. And so we then correlated the areas of the brain and the entropy with their IQ scores.

BM:    Well what is it about that activity - that high brain entropy and intelligence  - that is related? 

GS:  Well I think that the idea of readiness to understand whatever may come is really fundamental. That's really important about understanding the world, and may be important in some brain disorders. For example an area I study is post-traumatic stress disorder. We would predict - and we're actually studying this now - that in that sort of disorder you might have lower entropy.  You may be fixed, you may be really inflexible about understanding what may come, and only look at it as threat information.

BM:  Can you have too much entropy and have that be a problem?

GS:  There's been a study looking at disorders like schizophrenia around too much disorganization of the brain - you'll have a problem understanding your world, you'll be confused about your world that sort of thing. This whole thing is really ripe for study around how exactly entropy works. I think we start with what is the most fundamental thing. How does the brain use information? Because that's really what intelligence is. And then with that you could see well what might go wrong with that.

BM:  Is there any way that we could adjust our brain entropy? If it's too low, bring it up so we can be smarter. If it's too high and we're distracted level it out? 

GS:  I've been asked that before and I don't really know the answer to that.  But one of the things I think about is that maybe if you're treating a given condition that has known entropy problems - either too high or too low - maybe you can track the effectiveness of treatment by how it changes entropy. It's really unexplored and I'm very excited about that.