How your brain could trick you into lying without knowing it, and other odd brain disorders

PUBLISHED : Saturday, 11 July, 2015, 5:44pm
UPDATED : Saturday, 11 July, 2015, 5:44pm


Author Sam Kean was sure that the scientists had got it wrong. He'd just read an account of a woman who suffered a brain injury that left her unable to speak. But somehow, she continued to sing. And when provoked, she'd swear. Yet another scientific paper discussed patients who woke up unable to recognise animals after they recovered from an attack of the herpes virus. A shoe? Yep. A maple tree? No problem. But the family's pet cat left them bewildered and at a loss.

"These papers were about brain damage that was so specific that I thought they could not possibly be true," says Kean, 36, of Washington. "I thought that the authors had made an error. I set out to prove them wrong, and I found that, of course, it was I who was wrong. I found these cases funny and kind of cool. I thought it would be interesting to find out how the brain works. That's when a light bulb went off in my head."

The result is the engaging and accessible history of the human brain, The Tale of the Dueling Neurosurgeons, which travels back and forth between the 1500s to the present. Some case histories are extremely rare - a few gifted blind people can "see" through their tongues - while others provide insight into everyday questions, such as why some people struggle to remember faces. Kean spoke to Mary Carole McCauley about his new book .

Tell us about alien hand syndrome.

It's like having someone else's hand attached to your body. The hand is yours, but on some level you're not controlling it. It's grabbing and doing things that you're not consciously willing it to do. It can be dangerous if it grabs the steering wheel or pulls a pot off the stove. Sometimes, it's more humorous. You might be pulling up your pants with one hand and pulling them down with the other.

What's going on is that the conscious part of most people's brains sends out a signal to one hand to do something, and to the other hand to inhibit it from doing that thing. If an apple is sitting in front of you, a healthy brain will send a signal to one hand to grab it. The other hand will get an inhibition signal saying, "OK, just cool it. The dominant hand is going to take care of this." If a passageway called the corpus callosum is broken or damaged or not working right, the other hand doesn't get the signal to stop, and reaches out and flails on its own.

Your book also posits an explanation for false memories - why we can believe so staunchly in a particular event, even in the face of irrefutable evidence that it didn't happen the way we remember.

We think of our minds as video recorders that passively take in information. But neurons aren't like cameras. They're flexible, and the circuits in our brains can change over time. Emotions can change memories, and memories can bleed into one another. Imagine a memory as a series of photographs stacked on top of one another. It's not like there's a different photograph for each memory. It's more like a memory is a compilation of photographs. Probably, there's been no pressure through evolution to develop memories that are more accurate than that. We can get by on memories that are pretty good or close enough.

Tell us about "honest lying", a phenomenon that the book attributes to a nutritional deficiency in the form of a lack of thiamine.

"Confabulation" is when someone tells a lie but doesn't quite realise they're lying. It's a well-documented but really strange condition. What they're saying isn't true, but they're not trying to deceive you. They're honestly trying to give you information. Often, it happens with alcoholism, because alcohol prevents the intestines from absorbing the thiamine in food.

You'll say, "What did you do last night?" The patient will have been in an institution for the past 15 years, but say, "Oh, well, last night I was in Paris and I had duck for dinner and walked down to the Eiffel Tower." Often what people are doing is recalling memories at random and blurting them out. Their ability to recall is shot. They get a little panicked, especially if you ask them something big, like the names of their children. If you don't know the answer to that question, you're a terrible person, so they figure it's better to just blurt something out.

Your book explores a possible connection between the neurological disorder kuru and Alzheimer's disease.

We don't exactly know what the underlying cause of Alzheimer's is, but there are these protein plaques and tangles that look similar in people with kuru and Alzheimer's and Creutzfeldt-Jakob disease, which is the human form of mad cow disease. Alzheimer's may be a prion disease that causes degeneration of the brain. [A prion is a misfolded, infectious protein molecule.] Even though these diseases look so different on the surface, there may be some deep-down, underlying connection between them. There are even some genes that are active in kuru that might play some role in Alzheimer's.

Tribune News Service