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

Benefits from playing action video games

I just finished reading a recent review by Dapne Bavelier about the benefits of playing action video games. This review does not address the controversial issue of whether video games cause people to become more violent or not (I am personally on the fence on that one).

Rather, this review focus on the effects on more basic perceptual processes, and how playing video games affects these abilities. All this is put within a "learning to learn" framework. That is, will playing action video games help you find patterns or gain knowledge when you are not playing video games as well.

The pattern is very clear here. Video games will help you in a number of different ways. People who play action video games (sim city or civilization won't do), are faster at identifying objects, without making more errors, there are not as easily distracted by irrelevant stimuli, and they have greater contrast sensitivity. It seems as though video games enhances eyesight in general.

There are also substantial benefits in certain cognitive functions. People who play action video games enhance their ability to perform mental rotations (ex determining which 3D shape matches another 3D shape). Mental rotation in turn correlates with improved mathematical skills. Multi-tasking is another cognitive function that is improved in video game players.

Significant improvements have also been seen in decision making and reaction times. These factors may determine whether you brake in time to prevent a traffic accident or whether you die.

Thus in general, playing action video games improve a broad range of perceptual/cognitive abilities which probably helps the individual find relevant information in the environment, even though that environment does not involve war.

The objection which I am sure that some of you have thought of already is the classic "correlation does not equal causation". Maybe people who are good at all of these perceptual/cognitive tasks to begin with like video games more and therefore play more. Indeed, it you are slow, you get killed a lot in many of these games which can be very discouraging (I have played a little bit online and it sucks when you get shot 30 times over by a ten year old).

Researchers of course anticipate this objection and therefore conduct controlled studies. For instance you can take a random group of student with equivalent video game experience and then pay them to play either call of duty or civilization (a turn based game) for a few hours per day for a week or so. Differences between these groups after the intervention are probably due to the different treatments. Such controlled studies support the conclusions above, video games really do improve perceptual/cognitive functions.

So depending on whether you think action video games will increase aggression (like I said, I think the jury is still out on that one), if your child is playing violent video games and still not missing out of school etc, then you might even want to encourage this.



Bavelier D, Green CS, Pouget A, & Schrater P (2012). Brain plasticity through the life span: learning to learn and action video games. Annual review of neuroscience, 35, 391-416 PMID: 22715883

Sports and superstitions

I have a confession. Even though I feel that "sophisticated scientists" such as myself should be spending their free time analyzing their environment or reading philosophy or something else that is just so intellectual, I cannot help the fact that I love football (or soccer if you are an American).

Since I was four years old and my role model at the time, Peter Schmeichel played at the club I have been a loyal Manchester United supporter. I probably watch at least ninety percent of their games live on TV and have seen them once in real life. Much to my wife's distaste, the perfect Saturday for me involves crisps, beer, feet on the table and Manchester United performing one of their amazing comebacks in Fergie time against a rival such as Manchester City.

I acknowledge that there are many things you could potentially dislike about sports in general and football in particular. The extremely childish supporters is the first thing that comes to mind. Though Manchester City is of course a despicable and arrogant team that would be nobodies had it not been for oil money (;)), I would never dream of starting a fight or a brawl because another person were supporting them. I really don't see the point of that. Yet many people apparently do not see it that way and gladly put themselves in harms way to get a chance to best supporters from the other team. My own hypothesis is that such people merely use sports as am excuse to be able to do stupid things they would have done anyway.

The gambling aspect of the sports world is perhaps equally ugly. Gambling is of course intrinsically attractive to the human mind and winning a bet feels rewarding in the same way that taking drugs is rewarding. I am confident that people would gamble independent of sports but I still get a bad taste when I think of the way that sports and soccer in particular gets associated with gambling. This actually takes me to what I really wanted to write about here. Sports association with gambling and violence is very is unfortunate even if sports may only be the current outlet for basic human instincts.

What annoys me most however is all the superstitious sport stars out there. Today, when Bayern München take on Barcelona in the champions league semi final it is a fair bet that Lionel Messi will score a goal, because that is what he does. Who will get the credit if he does indeed manage to dance past 10 german goliats? You can be assured that Messi will point to the sky as if to say that it is God who awarded him the goal. If we grant for  a moment that God really does exist, would he really care who won the game and if so would he use his divine powers to interfere in a game and award one team a goal. If he is prepared to let innocent children starve to death every day, would he really use his powers to interfere in a soccer game? Messi is not the worst though. Javier Hernandez flamboyant religious displays makes Messi seem discrete. Before every game, Hernandez goes down on his knees on the midline, closes his eyes, raises his arms and brings his thump and index finger together. He sits there for about half a minute, then gets up and plays. Now if I was a soccer player I would feel quite odd at this sight, and judging by the look of his Manchester United team mates, they do too (a feeling that is probably shared by the other 70.000 people attending the game, plus another 50 million people at home). Thankfully, Hernandez is a so called super-sub which means that he only starts a minority of all the games (is this because Fergie thinks it is stupid too?).

Why do so many sport stars continue believing that they are benefactors of divine intervention? Apart from not having thought it through, my guess is that they are victims of schedules of random reinforcements. If a rat is rewarded with sweet tasking food every time he/she presses a lever, it get boring quite soon. If the rat gets a reward after a specified number of lever presses, he or she will keep going a bit longer. However, if the rat is rewarded after a randomized number of lever presses they will keep pressing that lever for a very long time.

For anyone who is giggling, thinking "silly rats", I want to immediately point out that humans are the same. If you go to Las Vegas or Macao (which I learned have casinos that earn six times as much as Las Vegas), you will see many people pressing levers for rewards that come after a randomized number of trials. Oftentimes, these rats... no I mean... humans, will spend all their money to perform these lever presses.

So back to sport stars. On some occasions Hernandez prayers will coincide with scoring a goal or even two goals. It does evidently not happen on every occasion, but sometimes. In other words Hernandez is really just like a rat pressing a lever... Whenever he gets the reward (such as a goal), it will be hugely rewarding, thus reinforcing the behavior. This explains all sorts of superstitions in sports (I only used Hernandez as an example). For instance, swedish hockey player usually don't shave throughout the end-season, and I have even heard rumors that they don't wash their underwear, which makes me look like a pretty good husband despite my love for football

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