The eyes don't lie

Think back to the last time you used your car, or your bike, to get somewhere. When you reached your destination, what color was the car or the bike parked nearest to yours? Can you remember? Chances are, unless you opened your car door too fast and dinged the one next to you, you probably can’t remember. Now what if I was to tell you that while you can’t consciously recall this information, your brain might still know it? What if there was a way to get at this information? A recent study in the journal Neuron suggests there is a way: by reading your mind through your eyes.

The researchers made participants study three different scenes (for example, a park, a lake, a kitchen) each superimposed with a different face. After a short break, the participants had to do a test. They would be presented with one of the three scenes from the study phase, and after a delay, all three faces seen in the study phase were superimposed on the test scene. All the participants had to do was identify which of the three faces was the one that initially corresponded with the test scene. During the test, two parameters were evaluated: the first one was whether the participant correctly identified which face corresponded with the test scene, and the second parameter was where the participant was looking on the screen, and how much time he or she spent looking at each of the three faces. This was done through a technique called eye-tracking, where a camera records the position of your eye-gaze.

Here is an example of the task

What the researchers found is that the participant’s eyes spent significantly more time viewing the correct matching face (the “right answer”), even when the participant selected an incorrect face as the answer. So what this means is that even when the participants couldn’t consciously remember which of the three faces was the right one, their eyes lingered the longest on the correct face.

In addition to the eye-tracking study, the researchers were looking at brain signals from the participants and determined that the hippocampus, a brain region we already knew was involved in conscious memory retrieval, was also supporting memory even when the participants were making incorrect responses. In a way, this means that your hippocampus supports the expression of memories through your eye-movements, even when you’re not consciously remembering correctly.

The relevance of this study lies in the fact that in some circumstances, the movements of your eyes is a more truthful and reliable account of memories than your verbal accounts. I’m sure you can imagine instances when this could be helpful: for example, to study the memory processes of non-verbal beings, such as babies or chimpanzees (who doesn’t want to know what a chimpanzee is thinking?). However, eye-tracking could also be used to get information from someone who is attempting to withhold it (surely, a more acceptable alternative to waterboarding). So next time you have something to hide, invest in a good pair of sunglasses…

This guy wants to know what you're thinking.

Reference: The eyes have it: hippocampal activity predicts expression of memory in eye movements. (2009) Hannula DE, Ranganath C. Neuron 63:592-599.

Saving the humble pie for another day

The results are in: Scientific Chick won the 2009 Canadian Blog Award for best blog in the Science and Technology category!

Since this was rather unexpected, I did not prepare a speech. But I do want to say big thanks to everyone who voted! I really enjoy writing this blog, and it means a lot to me that there are people out there who enjoy reading it.

Thank you!

Cell phones: curing brain diseases since 2010

If you are like most people, and in particular like everyone I take transit with on a daily basis, you probably spend a fair amount of time talking on your cell phone. If that’s the case, you’ll probably be happy to learn that in 2007, the World Health Organization declared that cell phones are A-ok. Nothing to worry about health wise. Not at all like sticking your head in a microwave. But you’ll be even happier to learn that in 2010 (fresh off the press!), a study published in the Journal of Alzheimer’s Disease suggests that not only is using your cell phone harmless, it might actually be good for you.

The researchers looked at the effect of exposing mice to high frequency electromagnetic fields (similar to the ones you are exposed to when chatting on your cell phone) for a long period of time (2 hours a day for 8 months). They used both normal mice and a mouse model of Alzheimer’s disease. An Alzheimer’s mouse is a transgenic mouse that has a gene that causes some of the manifestations of Alzheimer’s disease in humans.

At the start of the study, before the exposure to the electromagnetic fields, the researchers tested the mice on memory tasks, and as expected, the Alzheimer’s mice were clearly impaired compared with the normal mice. After two months of exposure, no change was observed in either type of mouse. However, after 8 months of exposure to the cell phone-like electromagnetic fields, the Alzheimer’s mice did significantly better on memory tests compared with Alzheimer’s mice who didn’t receive the treatment. Normal, non-Alzheimer’s mice also showed cognitive benefits due to the electromagnetic fields compared with normal mice that didn’t get the treatment.

Time to get Grandma a cell phone? Not so fast.

You may have seen this story in the news. It may have sounded like we finally found a cure for Alzheimer’s disease, and, as a bonus, it’s non-invasive and has no side effects. You may have started thinking of a business plan that involves sewing cell phones into pillowcases for the elderly. Trust me, I thought of this. However, as per usual in the world of science, it’s probably not that simple.

First, I can tell you this: mice skulls are thin, weak, and very easy to cut through with just a regular pair of tiny scissors (how sad is it that I know this from experience?). The skull of a mouse is very different from that of a human, and this means that while the electromagnetic field might penetrate well into mice brains, this may not happen in humans.

Second, the mouse model of Alzheimer’s disease, while widely used and our best tool for these types of studies, is flawed. So extrapolating the results to human Alzheimer’s disease is definitely premature.

Third, if you read the article carefully (I did it for you, so no worries), you’ll find that exposing the older mice to electromagnetic fields has one interesting side effect: an increase in body temperature. It then becomes difficult to tell if the memory enhancement observed is due to the temperature change or the electromagnetic fields. However, this is not necessarily a bad thing. I, for one, would much prefer to prevent cognitive decline by a daily regimen of quiet hot baths then by talking on the phone (though when I was a teenager, my mom would have guessed otherwise).

Finally, there was another sneaky side effect to the exposure, one that was seen only in younger mice: a decrease in three brain compounds involved in battling oxidative stress, including a very important antioxidant. The authors go over this finding somewhat quickly, and suggest that this can be interpreted as a good thing. Unfortunately, I happen to have studied this particular antioxidant quite a bit and I am of the opinion that the finding can also be interpreted as a very bad thing.

Overall, I don’t want to sound like a complete downer. This study was well conducted, showcases very interesting findings, and certainly gives us hope that maybe something can be done for Alzheimer’s disease. But I won’t be sowing a cell phone in my pillow just yet.


Reference: Electromagnetic field treatment protects against and reverses cognitive impairment in Alzheimer’s disease mice. (2010) Arendash GW, Sanchez-Ramos J, Mori T, Mamcarz M, Lin Z, Runfeldt M, Wang L, Zhang G, Sava V, Tan J, Cao C. Journal of Alzheimer’s Disease 19:191-210.

Black and white television

The United States recently elected their first black president. In this era of multiculturalism, can we consider ourselves a race-blind society? If you were to ask around, chances are most people would claim they do not behave in a racist fashion. Unfortunately, racial biases are still around us, and a recent study in Science makes a worrying discovery about the subtlety of racial biases in every day television programming.

The study looked at 11 popular television shows that include recurring white and black characters of roughly equal status (for example, characters could include a black detective and a white detective or a white doctor and a black doctor, and overall, black and white characters are equivalently distributed in the hierarchy). The researchers selected sample clips from the 11 shows and removed the audio track. They then asked a number of white young adults to watch the soundless clips and rate how well each character seemed to be treated by other characters and how much it seemed each character was liked.

You’d think if the character statuses are roughly equal, they would elicit similar non-verbal responses. Well, think again. Overall, white characters elicited significantly more favorable responses when compared with black characters, meaning the subjects rating the clips thought that the white characters seemed more liked and better treated by others than black characters. The interpretation of this study is that common television programming exposes us to race biases. The subtlety of this bias lies in the fact that it is non-verbal: when a new group of white young adults was asked to read the written transcript of the clips, no such biases were found. The researchers then took the study further and showed that the perception of the non-verbal biases in television shows can influence one’s race association and racial attitudes.

What is the reason for the presence of this race bias in television shows? Are the actors spontaneously generating them? Are they scripted? What other types of biases might be communicated through television? This study definitely gives us food for thought…

Reference: The subtle transmission of race bias via televised nonverbal behavior (2009) Weisbuch M., Pauker K., Ambady N. Science 326:1711-4

Move over, monkeys, there's a new smart animal in town

We used to think that the use of tools was a hallmark of our human species. Then we learned that in fact, some primates also use tools. For example, orangutans will use a stick to poke at ant hills to collect the fleeing ants for a tasty snack. The real piece of humble pie came when we discovered that birds also use tools. That’s right. Tiny-brained crows are able to use a curved stick to get at a treat in a tight spot. So I can’t say that it came as a shock to learn that the octopus, an invertebrate, also recently joined the smarty-pants tool-using club.

Most people who spend all day procrastinating working at their desk and have internet access probably already saw this neat video featuring an octopus carrying around a coconut shell and hiding in it:



In a recent article published in the journal Current Biology (which includes the video above), researchers describe how octopuses (also called octopodes, I had to look this up) carry coconut shells for later defensive use. The octopuses are seen scurrying around (on distances up to 20 meters!) with the shells cumbersomely positioned between their tentacles, and later assemble the two halves of coconut shells and hide inside. The authors stress that the interesting feature of this behavior is that when the octopuses are carrying the shells, they are at an increased predator risk, because they move slower than normal and their heads are exposed. Therefore, the only benefit of carrying the shells is the future use of these shells as a shelter. Apparently, that’s an amazing display of foresight for an organism that uses most of it brain cells to control its too many limbs.

While the video is definitely captivating, I think that whether this study is groundbreaking or not depends a lot on what the definition for “tool use” is. In the article, the researchers state that “a tool provides no benefit until it is used for a specific purpose”, so shelters like those of the hermit crabs don’t qualify. But even though the shells are used at a later time point, I’m not sure about calling them “tools”. I guess I mostly see them as a shelter. Is a shelter a defensive tool? Ah, semantics…


Reference: Defensive tool use in a coconut-carrying octopus. (2009) Finn JK, Tregenza T, Norman MD. Current Biology 19(23) :1069-70.

Personal space invaders

My last post was about H.M., a man who was missing a part of his brain called the hippocampus. Studying H.M. helped us to greatly improve our understanding of several functions of this brain region. Needless to say, after all the attention generated by the study of this patient, every neuroscientist out there was on the hunt for a patient missing different parts of their brain. By this time, gone was the era when we could butcher people just for kicks, so scientists waited around.

Luck struck a group of scientists from California recently. They came across patient S.M., a 42 year-old woman missing her entire amygdala, a part of your brain not very far from the hippocampus. Studying this woman confirmed a lot of things we already knew about the amygdala, for example that it’s important for fear. However, S.M. thought us something new: the amygdala is the part of your brain that controls your perception of an elusive concept: personal space.

The study of S.M. consisted of having her indicate to the experimenter at which point she felt uncomfortable while a person would approach her from across the room. The chin-to-chin preferred distance was then compared with that of healthy, age-matched controls. S.M.’s preferred distance was significantly smaller than the preferred distance of the control subjects. To make sure this wasn’t due to some random fluke, quite a few factors that may influence personal space were controlled for, including presence or absence of eye-contact, familiarity with the person approaching, etc. All in all, there was really no situation that could make S.M. uncomfortable, even when the person would move towards her all the way to the point of touching. The weird thing is that S.M. knew she should feel uncomfortable, and she understood the concept of personal space, but she just wasn’t experiencing it.

It always amazes me to find out that something so vague, so variable (people who live in densely populated places typically have smaller personal spaces), and so elusive is actually regulated by a huge chunk of your brain. It leads me to wonder: is there a part of us, of our mind, of our personality, that isn’t already hardwired in our brain?

While S.M. gave us great insight into the biological basis of personal space, the greatest contribution of this study is possibly the ugliest journal cover image of all times:

Is the point of this story really conveyed by
a woman's face in some guy's armpit?

Reference: Personal space regulation by the human amygdala. (2009) Kennedy D.P., Glascher J., Tyszka J.M., Adolphs R. Nature Neuroscience, 12(10):1226-7.

A memorable amnesiac

When little Henry Molaison was 7 years old, he fell off his bicycle. Little did he know that this event was possibly the first link in a chain of events that eventually made him the most famous patient in the history of neuroscience.

Sometime after his bicycle accident, Henry started having seizures. At first they were just little seizures. Then, when he was 16, he had his first major seizure, and it all went downhill from there. Unable to hold a job and not responding to the anticonvulsant drugs that were available, Henry and his family considered a brain operation. His surgeon, Dr. Scoville, wanted to try a new experimental type of surgery, and Henry went for it. So in 1953, when Henry was just 27 years old, he got both his medial temporal lobes removed (kind of like a lobotomy, but instead of removing the front of the brain, they removed part of the sides, just about at the level of your ears).

The operation was extremely successful: the seizures stopped! Unfortunately, this happy outcome was overshadowed by a very strange “side effect”: Henry now suffered from severe anterograde amnesia, meaning he could no longer form new memories. He also suffered from retrograde amnesia: he could not remember events from three to four days prior to the operation, and other events from a more distant past. But the anterograde amnesia was the most astonishing. You could have a conversation with Henry, then leave the room for a few minutes, and when you came back, it was as if he had never met you. Can you imagine?

Dr. Scoville called on one of his friends, Dr Penfield (that’s right, Wilder Penfield, from Montréal!) who then sent his graduate student, Brenda Milner, to study Henry. Even after all that had happened to him, Henry remained a friendly guy and was okay with being studied extensively. The knowledge we gained from Henry (known as H.M. until his death to preserve his anonymity) laid the foundations for much of what we know today about memory (which, I agree, isn’t all that much, but still). For example, prior to Henry, it was thought that memories formed all over the brain. Studying him taught us that instead it is the hippocampus, a part of the brain that was removed during his operation, that is crucial in forming memories. Studying Henry also taught us that there are multiple memory systems, a most unexpected discovery. While Henry couldn’t remember what he had for breakfast 10 minutes ago, he could learn a new task, like drawing a star while only looking at his hand in a mirror (do try this at home to understand the challenge it represents). He would get progressively better and faster at it but never remembered doing the task before. This went on until one day he drew the star and exclaimed: “This was much easier than I thought it would be!”. This lead to the notion that there are different types of memory such as declarative (conscious knowledge of facts and events) and procedural (skill-based knowledge).

The reason I’m bringing up Henry today is because this week, one year after his death, neuroscientists at UCSD started slicing up Henry’s brain in extremely thin slices. These slices will be available for scientists all over the world to look at, analyze and study. Even though he’s gone, there is no doubt we still have much to learn from the most famous neuroscience patient.


Reference: The legacy of patient H.M. for neuroscience (2009) Squire, L. R. Neuron 61(1):6-9