Confidence is shown by nerve cell activity


Should I or should I not? The activity of individual nerve cells in the brain tells us how confident we are in our conclusions. This is revealed by a recent study by researchers in the University of Bonn. The result is unexpected – the researchers were actually on the trail of a completely different evaluation mechanism.

You’re sitting at a café and want to enjoy a piece of cake with Your cappuccino. The Black Forest gateau is simply too rich for you and is therefore quickly removed. Selecting between the carrot cake and the rhubarb crumble is considerably trickier: The hot weather favors the refreshingly fruity cake. Carrot cake, however, is one of your favorites that are all-time. What to do?

Daily we have to make decisions, and we are much more confident about a number of them than others. Researchers in the University Hospital Bonn have identified nerve cells in the brain whose activity suggests the confidence in decisions. A total of twelve men and women took part in their experimentation. “We showed them photos of two different snacks, for example a chocolate bar and a bag of chips,” explains Prof. Dr. Dr. Florian Mormann from the Department of Epileptology. “They were then asked to use a slider to indicate which of these alternatives they would rather eat.” The more they transferred the slider from the center position towards the left or right photograph, the more confident they were in their decision.

Fire rate and assurance are related

Participants had to judge a total of 190 distinct snack pairs this way. “For example, some fired frequently, the more confident the respective test individual was in their choice.”

It is the first time that such a correlation between activity and decision assurance was identified. The affected neurons can be found in a brain region that plays a role in memory systems. “It is possible that we not only store what decision we made, but also how confident we were in it,” speculates Mormann. “Perhaps such a learning process saves us from future wrong decisions.”

Ethical reasons usually forbid the analysis of this state of individual neurons in living humans. In this type of the disease, the feature seizures always start in the same section of the brain. One possible treatment is therefore to remove this epileptic focus . To pinpoint the precise location of the faulty website, the physicians at the Clinic to get Epileptology implant several electrodes from the patient. These are distributed over the whole potentially affected region. At precisely the exact same time, they also permit an insight into the functioning of human nerve cells in the brain.

Researchers at the University of Bonn were originally looking for a subjective value to each of the alternatives. “There is evidence that this subjective value is also reflected in the activity of individual neurons,” says Mormann. “The fact that we instead came across this connection between fire behavior and decision confidence surprised even us.”

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