Mind biology

Everything depends on the eye of the beholder, but what are the biological processes in the brain that make us see, perceive and experience things the way we do?

By Eline Mørch Jensen

The question of how we perceive and experience things - for instance when we have to solve various tasks - and how this can be measured in nerve cells has occupied Søren Kyllingsbæk, professor at the Department of Psychology at the University of Copenhagen and PhD in visual cognition, for more than 20 years.

Just as it has occupied associate professor Thomas Habekost and Professor Claus Bundesen, the latter having worked in this field since the early 1970s and happens to be Søren Kyllingsbæk´s old PhD supervisor. The three have now, in collaboration with a handful of postdocs and PhD students, come together to clarify the problem in the context of the research project "Dynamical systems: mathematical modelling and statistical methods in social science, health and science."

- The focus of our work both past and future is attention and perception. We examine the biological processes happening in the brain when we, for instance, determine whether what we are looking at is a letter or a number. We know that the process takes place in the brain, but to understand what is happening we look, among other things, at how nerve cells are put together and work together, explains Søren Kyllingsbæk.

- The studies are carried out by means of experiments, on people with normal brains or with brain damages as well as on monkeys. We also use mathematical models. It all takes place in a continuous interaction in which we, through models, are able to come up with ideas for experiments that we otherwise would not have thought of - and vice versa, he adds.

The development of models takes place in an ongoing collaboration with Susanne Ditlevsen, professor of statistics and director of the research project "Dynamic systems". Thus the joint project should be seen as an extension of an already existing and fruitful cooperation in which mathematics, using Søren Kyllingsbæk´s words, connects the two levels - psychology and biology:

– As an example we have a model of what happens when you look at a letter for 10-200 milliseconds, that is, thousandths of a second. The model can predict what happens in nerve cells, how at first you are unable to see anything, but after a while might see the letter every tenth time it is shown. The model can also take into account what happens if we distract you, for instance by showing you both numbers and letters at the same time.

- The models can display different things, including how talented people are at staying focused and how resources are allocated. For example it is clearly easier to distinguish numbers from letters if they each have different, clearly defined colours.

But all brains don´t function the same way?

- No, of course not. You can´t predict people like you can clockwork, just as you can´t predict such a thing as radioactive decay and how it happens, Søren Kyllingsbæk concedes and continues:

– Some people are super-fast and able to perceive more than 100 letters or numbers per second. Interestingly it is often the case that if you are quick to process information, you most likely also have a good memory, but the variation is obviously enormous.

- Some human brains become weak or slower with age, some experience changes and debilitation associated with a brain injury while others keep the pace, but all that can be built into the model. Our knowledge of these individual differences, such as processing speed and short-term memory, which have been obtained partly through experiments, can be entered as different parameters in the models, says Søren Kyllingsbæk.

Is it possible to train the brain to function better and faster?

- Absolutely! We know this from such fields as the rehabilitation of patients with brain damage and from research into diseases such as dementia, depression and ADHD. I have also tested patients with brain damage caused by strokes, but mainly to better understand the processes in the normal or healthy brain.

So it is true: Doing crossword puzzles really does sharpen the brain?

- Yes, to a great extent you can easily train your brain and memory. Our brain is malleable and can allocate data; just as experience naturally is a helpful factor. One example could be ornithologists who are able to distinguish different species from each other and can see small differences that we, who don´t have the same training and experience, are unable to notice.

Søren Kyllingsbæk mentions that some of his colleagues are experimenting with giving subjects different substances, such as nicotine, to measure what happens in the brain in relation to the visual sense:

- Actually both good things and bad things come out of it: Nicotine makes some people leave the starting block more quickly as it enables them to take in information faster. But it's a speed which does not last for long. A bit like a race where someone is really good at getting a quick start, but then lacks the stamina to keep up the pace over a longer distance...

- We humans - or rather, our brains - are fairly flexible. In some tasks, for example in dangerous situations, it pays to react quickly, other times it is more important to accumulate information and draw on your experience.

But there probably isn’t a conscious choice behind it?

- No, but the brain seems to do what is most convenient, at least when there isn’t too much at stake. We are able to switch into this mode where the brain does not just say "this is red" or "here's a tiger", but instead attempts to orientate itself. For example by seeing things from different angles and trying to gather information by searching through the memory and drawing on experience gained - perhaps completely unconsciously, says Søren Kyllingsbæk, adding:

– Our brains would boil over if we constantly had to be aware of what goes on in the engine room - of what we do and why we do it!

The models which Søren Kyllingsbæk and his colleagues hope to develop and refine in collaboration with mathematicians and statisticians in the joint project will attempt to uncover more precisely what the nerve cells do. Or in other words: Whether we hold on to the first impression or the brain continues to accumulate information.

- This is actually the big issue that we are working to get closer to clarifying: Is the cell aware of both numbers and letters when it is presented with both or just one of the parts at a time; does it mix the two or choose to pay attention to one at a time.

- Imagine that you are looking through a cardboard tube and can only see what is in that very part of the visual field - that is how the individual cell "sees" the world. If there is only one object, the cell relays the signal as a signal point to a greater proportion of cells in the visual field, almost as if from a small branch into a tree full of branches. But what happens if there are two objects in the visual field? What does the cell then do? Does it report about the one object first or about both? Mixing them or switching between the two objects?

An important step towards a clarification is by way of experiments with monkeys located in Germany and England that Søren Kyllingsbæk and his colleagues have been allowed to latch on to, so to speak.

- Simply because in Denmark the field of study is not large enough to warrant the investment in the facilities needed. The reason for using monkeys and not people for these tests is that you have to open up into the brain and implant a sterile chamber to fit the electrodes in. Obviously you can´t do the same with human beings. But even though interest at home isn’t great enough we are fortunate that there are others who make their experimental results available for our research.

Søren Kyllingsbæk tells that the purpose of the experiments on which the research is based is to get the monkeys to solve some very simple tasks. The monkeys sit in front of a computer holding a joystick that they must use to choose between different options. They have been taught specific tasks, such as paying attention to a particular pattern and ignoring another and are given a reward when they perform the task correctly. During the process the electrodes measure the monkeys’ cells to see how they react to the visual information they are presented with.

And how do the results consist with your hypothesis? 

- As it stands right now, it is our hypothesis that the cells try to sort the information. Our idea is that the nerve cell does not mix irrelevant information simply because it makes better sense for the neurons to try to separate things. But this will have to be put to the test ... 

–I actually expect that there is a high probability that we will reach a clarification. It may seem like a small thing, but such a clarification would be of great importance to us, not least in relation to more efficient diagnoses and treatment of brain injuries. It is also certain to have a huge impact on the entire field of developing new and better assistive technologies, including such things as iPads - there is a Danish company (Seneye) working on how to use the eyes’ iris for controlling computers, for instance, adds Søren Kyllingsbæk. 

- The field in which we are experts in Denmark is the creation of advanced models for visual attention and perception. With this project mathematicians are given relevant problems to test their models on, and we on the other hand expect to gain new tools for measuring and analysing our increasingly complex data. Mathematics provides us with an added capacity for viewing and maintaining contexts that we would be unable to iimagine at any given moment, and to connect things and recognize patterns. 

- The area is not only interesting in relation to basic research, it is also very exciting at a philosophical level. I myself am very interested in the question of how psychology interacts with biology ... It's fascinating how our mind and body are connected and amazing that our experiences are simply biological processes in the brain – well, simple might be the wrong word to use! Søren Kyllingsbæk laughs and continues: 

- Math is an incredibly powerful tool that we can use to describe both biology and psychology; how the two are aspects of the same phenomenon. We are not able to know what it means to be a plant or an animal, but when it comes to ourselves - we human beings - we are able to look at it from the outside, through mathematical models, while also having the subjective angle – the fact that we actually see, perceive and experience things. 

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