Learning shapes decision making, study finds
Researchers in the UK have shed light on the neural mechanisms behind how learning affects decision making. Using functional magnetic resonance imaging (fMRI), they were able to identify which areas of the brain were involved in learning-dependent changes in decision processes. The study is published in the journal Neuron. Successful everyday choices, such as picking out the face of an acquaintance in a crowd, depend on the brain making decisions in an ever-changing environment. Selecting the best course of action is a complex process, as the brain has to deal with information that is often uncertain. While theoretical studies have shown that learning helps primates make decisions, the mechanisms that connect learning and flexible decision making have not been well understood. In the current study, researchers at the University of Birmingham asked eight subjects to separate 'Glass' patterns (white dots on a black background) into one of two categories: radiating or concentric. As the angles of the dots changed, though, determining the difference between the two categories required some careful thought. In the first of two experiments, the subjects were trained to use different decision criteria in two different sessions; this meant that patterns belonging to the same category according to one set of rules could belong to a different category based on the other. In the second experiment, their performance was measured before and after training. In both experiments, the researchers were able to change the way the subjects categorised the material through training. Using fMRI, they were able to see what regions of the brain were involved in these activities. 'What we have found is that learning from past experience actually rewires our brains so that we can categorise the things we are looking at, and respond appropriately to them in any context,' said lead researcher Dr Zoe Kourtzi. 'We have shown that this learning process is not just a matter of learning the structure of the physical world; when I look at something I'm not just playing a game of "snap" in my head where I try to match images to each other. In fact, areas in our brains are actually trained to learn the rules that determine the way we interpret sensory information,' she explained. The researchers observed activity in the frontal circuits of the brain (ventral premotor and premotor regions), which was to be expected since these areas have previously been found to be implicated in decision processes. The activity in this area reflected the subjects' choice on single trials as well as learning-dependent changes on the categorisation decision. But they were surprised to see that these changes were also evident in the higher occipitotemporal regions of the brain, which are known to be involved in the representation of visual forms. 'This flexible learning paradigm allowed us to test for brain changes related to the perceived rather than the physical similarity between visual patterns,' explained Dr. Kourtzi. 'Our use of brain imaging in combination with mathematical techniques enabled us to extract sensitive information about brain signals that reflected the participant's choice.' According to Dr Janet Allen, Director of Research at the UK's Biotechnology and Biological Sciences Research Council, 'We have to be able to understand how healthy brains work before we can see what has gone wrong when a person's brain is affected by disease. This work also shows that the complex human brain has evolved an incredibly effective mechanism for making good decisions that lead to successful everyday actions - something that has surely been a significant evolutionary advantage.' 'What we've shown is that we don't just get better at the task of picking out a familiar face amongst a crowd, for example. Our results tell us that previous experience can train circuits in our brains to recognise perceived categories rather than simply the physical similarity between visual patterns,' said Dr Kourtzi. 'Based on what we found, we propose that learned information about categories is actually retained in brain circuits in the posterior areas of the brain. From there, we think it is fed through to circuits in frontal areas that translate this information into flexible decisions and appropriate actions depending on the requirements and context of the task.'
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