Nerve cell activity shows how confident we are

Date:
October 9, 2020
Source:
University of Bonn
Summary:
Should I or shouldn't I? The activity of individual nerve cells
in the brain tells us how confident we are in our decisions. The
result is unexpected - the researchers were actually on the trail
of a completely different evaluation mechanism.



FULL STORY ========================================================================== Should I or shouldn't I? The activity of individual nerve cells in the
brain tells us how confident we are in our decisions. This is shown by
a recent study by researchers at the University of Bonn. The result is unexpected -- the researchers were actually on the trail of a completely different evaluation mechanism. The results are published in the journal Current Biology.


==========================================================================
You are sitting in a cafe' and want to enjoy a piece of cake with
your cappuccino. The Black Forest gateau is just too rich for you
and is therefore quickly eliminated. Choosing between the carrot cake
and the rhubarb crumble is much trickier: The warm weather favors the refreshingly fruity cake. Carrot cake, however, is one of your all-time favorites. So what to do? Every day we have to make decisions, and we
are much more confident about some of them than others. Researchers at
the University Hospital Bonn have now identified nerve cells in the
brain whose activity indicates the confidence in decisions. A total
of twelve men and women took part in their experiment. "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 moved the
slider from its center position towards the left or right photo, the
more confident they were in their decision.

Fire rate and confidence are related Participants had to judge a
total of 190 different snack pairs in this way. At the same time,
the scientists recorded the activity of 830 nerve cells each in the
so-called temporal lobe. "We discovered that the frequency of the
electrical pulses in some neurons, in other words their 'firing rate',
changed with increasing decision confidence," explains Mormann's colleague Alexander Unruh-Pinheiro. "For instance, some fired more frequently,
the more confident the respective test person was in their decision."
It is the first time that such a correlation between activity and decision confidence has been identified. The affected neurons are located in
a brain region that plays a role in memory processes. "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 prohibit the
study of the state of individual neurons in living humans. However, the participants in the study suffered from a severe form of epilepsy. In
this form of the disease, the characteristic seizures always start
in the same area of the brain. One possible treatment is therefore to
remove this epileptic focus surgically. To pinpoint the exact location
of the defective site, the doctors at the Clinic for Epileptology implant several electrodes in the patient. These are distributed over the entire potentially affected area. At the same time, they also allow an insight
into the functioning of individual nerve cells in the brain.

Researchers at the University of Bonn were originally looking for a
completely different phenomenon: When we make a decision, we assign 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."

========================================================================== Story Source: Materials provided by University_of_Bonn. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Alexander Unruh-Pinheiro, Michael R. Hill, Bernd Weber, Jan
Bostro"m,
Christian E. Elger, Florian Mormann. Single-Neuron Correlates of
Decision Confidence in the Human Medial Temporal Lobe. Current
Biology, 2020; DOI: 10.1016/j.cub.2020.09.021 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201009121928.htm

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