New research from our lab shows that individual neurons can produce timed responses

Previously, when I have blogged I have mostly written about other people's research. Yet sometimes our research group in Lund also publishes first class, revolutionary research. This monday (sep 29th 2014), Fredrik Johansson and colleagues (of which I am one), published a study that I believe will have a huge impact, not only within our own field of research (we study the cellular mechanisms underlying classical conditioning), but for neuroscience at large.

To understand the findings a little background is necessary. Since the 80s we have known that the cerebellum is required for the acquisition of conditioned eye-blink responses. If a subject repeatedly hears a tone and then, right after the tone, is hit with an air-puff on the eye, then eventually that subject will learn to blink in response to the tone. However, if one removes the cerebellum, subjects can no longer acquire these conditioned blink responses. Removing the cortex as well as the mid brain, on the other hand, has little effect on this type of learning.

An important feature of the conditioned blink response is that it is adaptively timed. This means that even if a very long tone precedes the air-puff, the subject will still blink just before the air-puff arrives. This may not seem particularly interesting however, no one know how the brain can produce such delayed responses. Neurons communicate with each other using action potentials which propagate at certain speeds, however, they never slow down anywhere near as much as would be necessary to achieve the type of delay seen during eyeblink conditioning (>100 milliseconds). This means that somewhere within the brain there must be a delay or a memory trace that essentially keeps track of time, thus allowing the subject to execute a certain action at the appropriate time. Such delays are not only seen following eyeblink conditioning, but in pretty much any type of behavior. If you move your lips 10-20 milliseconds too early or too late then your speech will no longer be comprehensible, and when Cristiano Ronaldo runs up to score a free kick, even minor timing errors will cause the ball to hit the stands instead of the net...

Recent research have shown that during eye-blink conditioning, Purkinje cells in the cerebellum acquire conditioned pause responses which are directly linked to the conditioned blink responses. These pauses are, just like the eye-blinks, delayed with respect to the tone, meaning that if we can understand how the delayed pause responses are generated then we may also be able to understand how delays in general appear. The long standing assumption has been that there are so called "delay lines" somewhere along the signal pathway that transmit information about the tone to the Purkinje cells. The tone activates sensory cells in the cochlea which activates cells in the brainstem which in turn passes the signal on to the cerebellum. If one cell type along this pathway maintain a change in its firing rate following this input, then this could explain how the delayed responses arise. However, Fredrik have now shown that this cannot be the case...

Fredrik, instead of using a tone (or equivalent), for conditioning, used stimulation of parallel fibers. These tiny fibers project directly to the Purkinje cell dendrites meaning that there is no possibility of any delay lines. We wanted to see whether the Purkinje cells would still have a delayed response when using parallel fiber stimulation. The results convincingly showed that this was the case. That is, even when stimulating the fibers right next to the Purkinje cells, we still got delayed responses. The implications of this finding are huge. The results show that individual neurons can produce delayed responses to a certain input. In neuroscience this is represents a paradigm shift because previously it has been assumed that we can understand the brain if map all connections between cells as well as the strength of those connections. This study shows that there is much more to the story than this. Unknown processes within the cells evidently play a key role in determining the firing pattern...


Johansson F, Jirenhed DA, Rasmussen A, Zucca R, & Hesslow G (2014). Memory trace and timing mechanism localized to cerebellar Purkinje cells. Proceedings of the National Academy of Sciences of the United States of America PMID: 25267641. http://dx.doi.org/10.1073/pnas.1415371111

Book review: The Willpower instinct by Kelly McGonigal (PhD)

Everyone thinks that their willpower fails them, often on a regular basis. Those people who say they have a lot of willpower often have the least. Willpower is undeniably good to have and in studies it is correlated with all kinds of positive outcomes.

Dr.McGonigal thankfully does not teach the reader never to “give in” to the things you like. Rather you should ask yourself what it is that you would like to stop/start doing and then focus on that goal. She refers to these goals as willpower challenges. Typical willpower challenges are to go to bed in time, to exercise more, to work instead of checking facebook updates, eat less snacks etc etc.

Most people have many willpower challenges. One important lesson from this book is that you do not have unlimited willpower. Therefore you should not take on too many willpower challenges simultaneously, because that will result in failure.

So what strategies does Dr.McGonigal propose for increasing willpower? This book includes a wealth of advice and I feel pretty confident in claiming that most people will find at least one strategy that helps them. Her first proposed strategy is meditation, which is just not my cup of tea (for me doing meditation would be a willpower challenge on its own). After taking about meditation and breathing exercises she moves on to more obvious candidates: exercise and sufficient sleep. I am sure that you have all heard it before but I will reiterate: exercise is good and getting enough sleep is important for all kinds of things, including willpower. Regarding sleep she also points out that people have started sleeping less in recent decades, and in the same time people have become more obese. In is not inconceivable that the rise in obesity in the recent decades in part is related to reduced willpower which in turn is due to the fact that we sleep less. After all, those evening snacks that we consume in the evening after a stressful day can contain quite a lot of calories.

Dr.McGonigal introduces plenty more strategies for overcoming willpower challenges. The ones I feel were most useful include the following: (1) If you really want say a snack, wait 10 minutes, and then, if you still want it, go ahead and take it. (2) Thinking more about your future self. People are often prone to ignoring the needs of their future selves I don’t care so much how their actions may affect their future selves. (3) Focusing on what you should do rather than what you shouldn’t do. Don’t think of pink elephants! Hard right? Similarly constantly telling yourself not to eat that snack will draw your attention to it, making it harder to resist. It is better to focus on what you should and do.   

There are many willpower traps. Perhaps the most obvious one is exposing yourself to the thing you try to avoid. If you want to eat less snacks, don’t keep them in the home cause if you are like me you will eat them, sooner or later. Another trap which I personally used to fall into, is rewarding yourself after a strenuous exercise i.e., now that I have exercised so much I deserve to eat several large burgers and some candy after that =). I am not saying that such a reward in undeserved, only that the calorie intake from a large meal is much larger than the calorie output during exercise. Yet another trap is the “what the hell effect”. Having succumbed to temptation many people say to themselves - what the hell, now that I have started eating this snack I might as well eat the rest...

I sum, this book provides an accessible introduction to willpower, what it is, how it works, and what you can do if you face a willpower challenge. Regardless of whether you decide to utilize any of Dr.McGonigal proposed strategies I believe that merely starting to think and learn about willpower will help you reach your personal goals. It is also nice to know that more or less everyone has willpower issues, and very few (sickly?) people never succumb to temptation.

The scope of your brain and your connectome

One cubic millimiter of brain tissue contains a hundred thousand (100.000) neurons. Between these 100.000 neurons there is 1 billion (1.000.000.000) connections. In one cubic millimeter that is!!! Your brain contains millions of miles of wiring, tens of times longer than the circumference of our planet.

Sebastian Seung recently published a book called "connectome" where he lays out the hypothesis that "you are your connectome". What is connectome you ask. Your connectome is all your neurons and the connections between all of your neuron. This statement is more attractive than the statement "you are your genes" because unlike genes, your connectome changes in response to everything that happens to you. I have not looked up the numbers, but I am in no doubt that every second of your life is associated with the formation of new synapses, destruction of other synapses and change in strength of yet other synapses.

The only way this hypothesis can really be tested is by mapping the human connectome, which, according to Seung (and I agree), won't happen for a few decades at least...


In the TED lecture professor Seung presents his ideas.



By the way, the brain actually does not contain 100 billion neurons but more like 86 billion neurons. And we do not just use 10% of our brain - we use 100%!



See also: The Human Connectome Project

Dead salmon sensing human emotions...(?)

As anyone who know me will testify, I am a strong proponent of the scientific method. It is quite simply the best available method we have to gain knowledge about the universe, and it has a fantastic track-record.

Theoretically, science is I think, flawless. However, science is done (mostly) by scientists, i.e. people, and we all know that people are, in general, not quite perfect. This is why scientists are so obsessed with writing out the method. Doing so means that other scientists can replicate the experiment and see if they get the same results.

One excellent replication of a scientific method was done by Bennet et. al. Bennet and his colleagues were concerned that a popular statistic method used for fMRI data actually produced statistically significant results that did not represent any real activity. fMRI, in short, is a method that that measures blood flow in the brain, which in turn, is a measure of neural activity (because brain regions with active neurons will consume more oxygen which is delivered by the blood). A statistically significant result is a result that is very unlikely to happen by chance alone.

As mentioned Bennet et al were concerned that a popular method for analyzing fMRI lead to unwarranted conclusions. To prove this he took a trip to the local market were he bought a Salmon, a dead, frozen salmon. He took this fish back to the laboratory and put it in the fMRI machine. The salmon was then shown pictures of situations depicting different emotions (e.g. anger). Bennet then used the fMRI data to see if there were differences in the dead and frozen salmon brain, depending on what type of situation it had just seen, and guess what, there was! Does this prove that dead and frozen salmon have the ability to see what type of emotion a particular situation depicts? No, of course not. Rather, the experiment is an elegant way of showing that the statistical method used lead to invalid conclusions.

See the poster, which is actually quite funny, here.

In a second example appeared in the excellent journal "Psychological Science". This article was perhaps more worrying since the the author Simmons and co-workers reached absurd conclusions using perfectly valid mathematical/statistical methods. Specifically the authors showed that when you listen to music about old age, you become younger - you don't feel younger, you actually get younger. They reached this conclusion simply by varying some decisions about the analysis, after the experiment was done, which is something I believe many scientists do. Ideally you should decide which exact tests you will use before the experiment and then stick with that analysis - if you find unexpected results these have to be checked in another experiment.

The good news is that science is self-correcting i.e. science, unlike say religion, eventually detects its own error, and it is also worth noting that in both examples above, scientists, following the scientific method, found the problems and reported them.

Backyard brains

The Nature neuroscience podcast, also known as the neuropod had this an interesting clip about a company called "Backyard Brains". Backyard brains is a company who tries to bring neuroscience to the amateurs. In other words they try to make neuroscience instruments cheap. Cheap here means that they sell you a "spiker box" for 99 USD. What can a spike box do? A spiker box will let you record action potentials from live cells. Further increasing the "coolness" of their product is that they have iphone/android applications that will let you display the spikes in your smartphone. As soon as I get a little bit richer I will buy one and then publish recordings from whatever I can find right here on this blog. This is seriously cool (and a little nerdy) stuff. Go buy!

Backyard Brains hope that their endeavor will lead to amateurs going into neuroscience and expand the field just like amateur astronomers have made very important contributions to the study of astronomy.

To conclude, although I have never tried the spikerbox I just cannot conceive a scenario where I would not love this thing. I you are still skeptical, check out their video below, it will blow you away!

New Teaching Company Neuroscience series with Sam Wang

Good news for everyone interested in hearing interesting and engaging neuroscience lectures. Sam Wang, who is in fact a big name in my own field (Cerebellum) has recently recorded a lecture series together with The Teaching Company. The lecture series is called Neuroscience in every day life and in the lecture series it seems (I have only read the titles of the lectures) that Wang touches upon basic neuroscience principles as well as the more sexy parts of Neuroscience (emotions, sex differences, happiness etc etc).

Although I have not listened to it myself I can testify that Sam Wang is a very good teacher. If you also take into account the fantastic quality of all productions from The Teaching Company I am sure no one will be disappointed.

Do we have a soul?

It is easy to get lost in a discussion about the existence or nonexistence of the soul. However, quite frequently conflicts do not arise because people disagree, but rather because they are using different definitions of the soul. Depending on the definition used I either believe or do not believe in the existence of a soul. A common though not very useful definition of "the soul" is what we really are, the core of our selves, or something like that. I would perhaps be inclined to call this "personality" rather than soul, but if that is what is meant by soul then yes, I think I do have one.

If on the other hand the soul is seen as something which is necessarily immaterial, then I do not believe in it. Hypothetically, should someone make an exact replica of me, with the exact same atoms in the exact same places, nothing more would be required. The replica and I would be impossible to distinguish from each other. The replica would react to any stimuli like me, would have the same childhood memories, be attracted to the same things, and just like me the replica would be disgusted by the smell of an orange.

This would not last long though. If me and my replica would continue our lives, then gradually subtle environmental differences would form us in non-identical ways, resulting in some small differences. These differences would ultimately affect the choices of me and my replica and consequently our preference would diverge. This, in turn, would lead to escalating environmental differences and increasingly different personalities or, if you prefer, souls. The resulting differences between me and my replica would be reflected in the way our atoms are put together, so we would no longer contain the exact same atoms. Nevertheless, there would probably be many striking similarities as well. There are examples of genetically identical twins that have grown up in very different environment, and still similarities have been extremely apparent.

What do I base this belief on? My main piece of evidence is that there does not seem to be any part of the personality that cannot be affected by brain injury. In my neuropsychology course I read about many patients with exotic brain injuries. A famous patient called HM, who is still alive, is unable to form any new memories. As a result he still thinks that he is 25 years old and he does not recognize the researchers who have visited him every day for several decades. Another older case is that of Phineas Gage who got a metal stick shot up through the frontal part of the brain. To everyone's amazement Gage did not die from the injury, however, according to his colleagues he was not the same after the injury. Following the injury he started swearing and behaved inappropriately to the extent that he lost his job. However, the most striking case that I can remember only vaguely is that of a responsible normal woman with three kids. Due to a tumor in her brain she suddenly underwent a radical personality change. Her behavior went from normative to completely reckless, and from being a good and faithful wife, she became extremely uninhibited and promiscuous…

One needs merely to take a look at a severe case of Alzheimer disease to see that material changes in the brain can change a person beyond recognition. Some would say that there is always something left, that even though Anna is now eating her own feces and hitting her children when they come to visit, she is still Anna, somewhere inside. I don't think so. Sure, she is still called Anna, and one can still recognize her appearance, but other than that Anna is not Anna anymore. The soul of Anna is very different from the soul Anna used to have before she got Alzheimer.

In sum, due to the fact that there seems to be no sacred part of the personality, nothing which cannot be affected by changes of a material nature. Due to this I do not believe that we have an immaterial soul. Normally I try to avoid the word altogether because of the confusion that arises, but this is my current thoughts on this issue. The discussion here has many important implications, for instance it should affect how to think about free will vs. determinism. I have written about that here.

Learning described at the cellular level: Finding from our laboratory in Lund

Today I want draw the attention to some very exciting discoveries from our neurophysiology laboratory here in Lund. Because I have just started working in the lab I cannot take any credit for the work, though I have been spending a lot of time lately, trying to develop the experimental setup further. Instead it is Dan Anders Jirenhed, Fredrik Bengtsson, and Germund Hesslow who have worked for several years to achieve the experimental setup that allowed the findings that you can read about here.

The findings have already received quite a lot of attention from places with more readers than my blog. See for instance the article in New Scientist, or if you understand Swedish you can listen or read about the discoveries on Sveriges Radio homepage. If you are interested in the technicalities I recommend that you read the original article which was published in the Journal of Neuroscience.

What has been found is a perfect correlate between behavioral learning and cellular behavior. To explain what this means you first have to know what classical conditioning is. To understand what classical conditioning is, imagine that you sit in a comfy chair (doesn't really matter whether it is comfy or not). Suddenly you hear a loud tone, and immediately after that you get a puff of air in your eye. If you have a normal brain you will blink when your eye is hit by the air. Now imagine that this occurs over and over again, first the tone, then the unpleasant air puff. Again, if you have a normal brain it will eventually realize that "aha, if I blink when I hear the tone, I can avoid that nasty puff of air in my eye, I think I will do that".

Though you may be conscious of the association between the tone and the air puff, this type of learning does not take place in the cortex of our brain, but rather in the cerebellum. Take away the cerebellum and this type of learning is severely impaired if not entirely abolished. In our laboratory we used tiny winy electrodes to measure the activity of single purkinje cells (see picture) in the cerebellum while presenting tones and air puffs. Purkinje cells are a type of neuron located in the cerebellar cortex (near the surface), which because of their morphology appear to be particularly good candidates for the learning that occurs during classical conditioning.

So in essence we could see what happened to the activity in this single purkinje cell when we were applying a classical conditioning paradigm (presenting tones and air puffs). If you just leave them alone, purkinje cells will fire action potentials at a rate of about 60Hz (60 times every second), however, amazingly during the learning paradigm described above the purkinje cells started to show a very distinct pause just prior to the presentation of the air puff (see picture). Change the time lag between the tone and the air puff, and the timing of the pause in the purkinje cell will change so that it is always perfectly synchronized with the air puff. Eliminate the association between the tone and the air puff by presenting only the tone without the air puff and the pause will disappear. Re-establish the association between the tone and the air puff and the pause in the purkinje cell will rapidly re-appear. In essence there is a perfect agreement between the behavior of the animal and the behavior of the purkinje cell.



So why is this so important? Well first of all it is just super interesting, I mean it appears that we can start to describe learning in terms of patterns of neuronal firing. This also means that we will soon be able to see what happens to learning during different treatments. One question that I find interesting is what would happen to the activity in the purkinje cell if we squirt some narcotics (e.g. Cannabis) onto the cell. Will the learning be damaged in some way. There are probably millions of follow up questions that we can now start to explore. All this because of the work done here in Lund, Sweden.

True cyborgs now a reality!

Muscular movements are controlled by the central nervous system. Right now my brain is actively planning the muscular contractions that will make my fingers exert a force on different buttons on my keyboard, ultimately resulting in the text that you are hopefully enjoying right now. How does this work? Well, there are many unsolved mysteries, but we have also learned quite a lot.
Two areas of the brain, the "supplementary motor area" (SMA) and the "premotor area" (PMA), seems to be involved in planning the exact series of muscle contractions that are required in order to do something such as writing this text. How do we know this? Put a person in an fMRI machine and ask them to imagine doing something, and wallah, SMA and PMA lights up (meaning that more blood is going to these areas, mening that more glucose gets there, meaning more activity in those cells)! In order to actually move you will also have to get your motor cortex involved. It is from this area that axons travel down into the spinal cord and elicits movements. If you stimulate the motor cortex electrically during a surgery (this is sometimes done to see how the body is mapped onto the motor cortex), then the corresponding muscles will contract, perhaps resulting in an arm or a leg flapping out. So when your SMA and PMA have planned the contractions they will communicate with the motor cortex which then sends signals down to the alpha motor neurons in your spinal cord which in turn will release acetylcholine onto the muscles causing them to contract. All this happens within a few milliseconds! (Of course other areas such as the basal ganglia and my own darling, the cerebellum are also involved in movements, this was merely a simplified account.)

Who cares?, where are the applications? Back in 1982 a guy named Georgopoulos measured the activity in the motor cortex of a monkey while it was performing some well defined motor tasks. Georgopoulos found that a certain movement would be associated with a particular pattern of activation in the motor cortex. Thus, merely by looking at the activation in the motor cortex he could predict that the monkey was trying to move say, its left index finger. This could be very useful for people suffering from paralysis. Theoretically it should be possible to measure motor cortex activity and from that see what movements the motor cortex is trying to do. Then, to help a paralysed patient what you need to do is to connect a robotic arm programmed to move in response to neuronal activity. This procedure is no longer science fiction, it is reality. In this article it is described how some surgeons used signals coming from the motor cortex to make a prosthetic arm move, in other words they made a true cyborg out of lucky Mitchell, 24.

Although I am pessimistic about the prospect of creating a brain that is as complex as our own I do think that in the future more and more applications like this one will appear.

Free will and determinism

Do we have free will, or are all our thoughts and actions a result of the physical forces in our universe?

After having taken part in a discussion about consciousness on Furiku's blog I decided to learn a little bit more about the philosophy of the mind which discusses such things as the nature of the mind, consciousness, and free will versus determinism. The audio-course, which I warmly recommend, is from the teaching company (see my previous post about the the teaching company here), and it is called "philosophy of the mind". Teacher is John Searle (see picture) from the University of California, Berkeley.

My experience is that the question of free will versus determinism is a question that many people ask themselves occasionally. Are we free agents in the world or does everything, and I mean everything have a preceding cause. I cannot speak for anyone else of course, but for me it sure feels like I have free will. When I write these words I feel as if I am deciding to write these words, and I can even erase them again if I want to! On the other hand, dwelling further into this I can think of situations in which I have felt as if I had no free will, where I acted contrary to the way I wanted to act. One of my stepchildren exemplifies this point well. In the process of doing something violent to her younger sibling she sometimes says "I just could not control myself", which effectively eliminates the possibility of telling her that "that was wrong!".

I should state here what I believe; I believe that we live in a determined universe, that free will is an illusion (that we are determined to have), and I will now explain why.

We have physical laws which can, with some small exceptions, explain more or less everything that goes on around us. In most chemical and physical systems we can, if we know the current state of the molecules in the system, predict how the same system will look in the future. Our brain is a chemical/physical system (a very complex one), and therefore it should be theoretically possible to predict what our brain will look like in the future, and if we had more knowledge about the relation between the physical and mental state of the brain we would be able to predict exactly, the mental states and behaviors of the individual.

Some people will object to my view by saying that, if I don't have free will, then everything is determined and it doesn't matter what I do. I could go out and rape and kill people and that would have been inevitable. However, if the deterministic hypothesis is true, then you could obviously not decide to go out and kill and rape. If you did go out to kill and rape, it would be because of something, maybe these words (caused by processes in my brain) have had an influence of your brain which makes you go and do this, or maybe you have gotten a tumor in your amygdala, messing up your emotions. A similar objection that I sometimes hear is the following. "How can you (referring to me), believe in such a depressing thing?" Life is meaningless without free will! Of course the answer is the same, if the deterministic hypothesis is true I cannot decide to believe or not believe in free will, my beliefs were determined by the state of the universe when it began. Besides, I don't really feel sad when I think that I have no free will, rather, I think, I am a little bit amused by this thought.

Another objection is that research in quantum mechanics have shown that there is uncertainty in the universe. We cannot tell the exact location of the electron when it is orbiting the nucleus of the atom, hence free will. To me this argument sounds rather far fetched and desperate. There is no plausible reason to suggest that we would be able to control, through our mental activity, where the electron is located, and there is also no good reason (as I see it), why the location of an electron in the orbital cloud should give rise to different actions.

Summing up, I just cannot see anyway around the conclusion that there is no such thing as free will. It free will did exist it would be a big problem for science which rests on the assumption that every process in the universe have a cause. I would love to hear comments on this post, especially from people who do believe in free will...

N400 and the beautiful is good stereotype continued, results from my current research

In a previous post I described my current research in which I tried to measure the beautiful is good stereotype using EEG. The idea is that when we are presented with something that contradicts our stereotypes, our brain says "wait a minute, those just don't go together, that is odd". It just so happens that there is an ERP component, called the N400, which is sensitive to mismatching stimuli.

So in my experiment, participants were presented with faces rated as either attractive or unattractive, followed by words rated as either positive or negative. Their EEG (their brain activity), was measured throughout the experiment. We expected to find that the magnitude of the N400 wave/component would be larger when presenting incongruous face-word pairs. Pairs that are incongruous contradict the stereotype, so in this experiment it would be attractive faces followed by negative words or unattractive faces followed by positive words.

So what did we find? Do our brains object when they see an attractive person followed by a negative trait or when an unattractive face is followed by a positive trait. In our experiment we found no N400 for attractive faces, however, we did find a clear effect for the unattractive faces. This supports the view that rather than having a "beautiful is good" stereotype we have an "ugly is bad" stereotype. Just to spell it out, our data showed that when the average participant was presented with an unattractive face followed by a positive word, the brain responded with a larger N400 component, indicating that there was a mismatch between the two stimuli, they did not go together. According to our data, it is much harder to imagine an unattractive person with positive traits than an attractive person with negative traits...

Another discovery that we made during the study is that there was a difference in the EEG that depended only on the type of face presented, that is the EEG activity following presentation of an attractive face is different from the EEG activity that follows the presentation of an unattractive face. Interestingly, the difference in EEG activity following presentation of either attractive or unattractive faces is highly similar to the difference that you see when you present pleasant or unpleasant stimuli. So it would seem that perceiving an attractive face will "reward" your brain. This is also supported by fMRI studies in which it has been shown that perception of attractive faces leads to activity in parts of our brain normally associated with reward.

If you are still curious and want a more complete description of the experiment you can download the entire article here.

The next step in our research is to investigate further what types of positive traits are associated with attractive and unattractive faces. A previous meta-analysis have shown that we associated attractiveness more with social competence than with intellectual competence. We are going to see whether this pattern we will also see this pattern when we measure the stereotype using N400. Furthermore, we are going to see if there is a link to memory. One could speculate that it is easier to remember face-word pairs that agree with our stereotype because we already have a developed network to store such information (or something like that). Or, alternatively, perhaps we remember incongruous information better because when we see something that does not agree with our stereotype we use lots of resources to reconcile it with what we know, and since the level of processing of a stimuli is correlated with how well we remember it, it is possible that we will remember incongruous pairs better. We will see...

Some interesting discoveries about pheromones

In order to prepare for my soon to start PhD studies, I have been reading a lot of neuroscience lately. I am currently reading a book called Neuroscience: Exploring the Brain by Bear et. al. (2006), a textbook that I warmly recommend to everyone interested in the field.

In this book there is a section about human pheromones which I found so fascinating that I thought I would share it with those few people who occasionally read this blog. Pheromones are basically small molecules that fall off us and are sometimes picked up by the nose of other people or (more likely) animals. Our pheromones tells our genotype and can work as a fingerprint even more accurate than the fingertip fingerprint. A bloodhound which has perhaps the most developed sense of smell of all animals has great difficulty in distinguishing between two identical twins. Fraternal twins on the other hand is piece of cake. An ewe will establish a life long memory of her lamb when it is born. Pregnant female mice will automatically trigger an abortion if they feel the smell of a male other than the one that impregnated her.

What about humans then. One rather well known, yet astonishing, effect of pheromones is the synchronization of women's menstrual period. When females are allowed to smell pads which have been under the arm of another female, their menstrual period will converge with the other females period. This happens even though the women do not feel any smell at all! Pheromones are also very much involved in our sex life, believe it or not. Evidence indicates, that by picking up pheromones we can sense whether the potential mate is a good match or not (in terms of genes). Napoleon (see picture) was probably one of the first people to realise what smells can do to your lust. He once wrote and asked Josephine not to bathe for two weeks(!), so that he could enjoy her aromas...

My current research project (fall 06) - Electrophysiology and stereotypes...

Since I am doing the "C-course" in psychology at Lund University, I am expected to carry out a research project. I was lucky to be allowed to use the rather new EEG lab that has been set up. This allowed me to do an experiment that I have been thinking about since the spring but which I have not had the chance to do until now

So what is my project about? I am actually trying to do something as sexy as measuring peoples' stereotypes using EEG. An EEG (see picture) measures the electrical activity that the brain generates. This electrical activity differs depending on what the brain is doing. If you are sleepy the brain will start to generate what is referred to as alpha waves (a funny consequence of this is that you can actually see when your subjects are starting to get fed up with your experiment), if you are dead there will be a straight line, an epileptic seizure is characterized by wild activity etc etc. In fact, the brain also generates characteristic wave patterns in response to certain events, these patterns are called event-related potentials or ERPs.

In my experiment I am looking at a specific wave called the N400, N because it is a negative deflection, and 400 because it occurs 400 milliseconds after the stimuli was presented. The N400 appears when our brain perceives something unexpected. For example, when the brain hears a sentence such as "Jack took the bus to town to meet some of his boxershorts", the brain says, wrooong!! (an N400 wave appears). Similarly, if famous faces from different occupations e.g. Robert De Niro and Billy the clown, are presented serially, the N400 also appears, thus suggesting that our brain has recognized that these two stimuli did not belong to the same category.

I am reasoning that stereotype incongruency, that is, things that go against your stereotype, will also elicit this N400 component. To test this prediction I have obtained a collection of attractive and unattractive faces as well as a collection of negative and positive words. Presumably the N400 component will appear when I present to my participants an attractive face followed by a negative word, or conversely an unattracitve face followed by a positive word. The reason I believe so is that there is a lot of evidence suggesting that we associate attractive faces with positive characteristics and unattractive faces with negative characteristics. To be continued...