Tracking the neurons that make us social

Date:
December 2, 2021
Source:
Universite' de Gene`ve
Summary:
Human beings, like most mammals, need social interactions to
live and develop. The processes that drive them towards each
other require decision making whose brain machinery is largely
misunderstood. To decipher this phenomenon, a team has studied
the neurobiological mechanisms at stake when two mice come into
contact through learning a task. They observed that the motivation
to invest in a social interaction is closely linked to the reward
system, via the activation of dopaminergic neurons.



FULL STORY ========================================================================== Human beings, like most mammals, need social interactions to live and
develop.

The processes that drive them towards each other require decision
making whose brain machinery is largely misunderstood. To decipher this phenomenon, a team from the University of Geneva (UNIGE) has studied
the neurobiological mechanisms at stake when two mice come into contact
through learning a task.

They observed that the motivation to invest in a social interaction is
closely linked to the reward system, via the activation of dopaminergic neurons. These results, to be read in the journal Nature Neuroscience,
will make it possible to study physiologically the possible dysfunctions
of these neurons in diseases affecting social interactions, such as
autism, schizophrenia or depression.


========================================================================== Social interaction is an integral part of our daily lives, although the intention to interact with others requires an effort to act. So why do
we do it? What is the mechanism behind the motivation we feel to engage
with others? To identify which neurobiological circuit is the basis of
social interaction, a team from the UNIGE, member of the National Centre
of Competence in Research (NCCR) Synapsy, observed what happens in the
brains of mice seeking the contact with their conspecific.

Social interaction is a natural reward "In order to observe which
neurons are activated during social interaction, we taught mice to
perform a simple task that allows them to enter in contact with their
fellows mice," explains Camilla Bellone, professor in the Department
of Basic Neuroscience at the UNIGE Faculty of Medicine and director of
the NCCR Synapsy. Two mice were placed in two different compartments
and separated by a door. When the first mouse pressed a lever, the door
opened temporarily, allowing social contact to be established with the
second mouse through a grid.

"As the experiment progressed, the mouse understood that it had to press
the lever to join its fellow mouse. With this task, we can measure
the effort the mice are willing to put to engage in interaction with conspecifics," continues Cle'ment Solie', a researcher in Camilla
Bellone's team.

Using electrodes, the scientists measured the activation of neurons. "We
found that the the interaction between two mice, similarly to other
natural reward, led to the activation of dopaminergic neurons, which are located within the reward system," says Camille Bellone. These neurons
release dopamine -- the so- called pleasure molecule -- which is crucial
for several motivated behaviours.

"What is even more interesting is that while during the first sessions,
the dopaminergic neurons are activated when the mice interact with the conspecific, as soon as the mouse learn the association between the lever
press and the interaction, the activity of dopaminergic neurons precede
the reward," continues Benoit Girard, researcher in the Department of
Basic Neuroscience.

"Similarly, if the mouse presses the lever but the door does not open
in the end, there is a sudden drop in the activity of the dopaminergic
neurons, indicating great disappointment in the mouse," explains Camilla Bellone. "This predicting signal is the neural substrate for learning and
is crucial for social motivation." Useful mechanisms for understanding
certain psychological illnesses Several psychiatric diseases such
as autism, schizophrenia or depression are characterised by social
dysfunctions and social motivation deficits are described in some of
these patients. Thanks to this study, scientists now know that these difficulties may result from dysfunctions within the reward system and
more precisely at the level of dopaminergic neurons. "We will now be able
to use these neurons as targets to find treatments for these diseases,"
says Benoit Girard. "Furthermore, the reward system is at the basis of
the occurrence of addictive behaviours. Whether the excessive use of
social media network could hijack the dopaminergic system and be at the
basis of maladaptive behaviours toward social media is an interesting hypothesis that can be now tested," notes Camilla Bellone. The Geneva
team will now focus its research on the study of these psychological
illnesses via the functioning of these neurobiological mechanisms.

========================================================================== Story Source: Materials provided by Universite'_de_Gene`ve. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Cle'ment Solie', Benoit Girard, Beatrice Righetti, Malika Tapparel,
Camilla Bellone. VTA dopamine neuron activity encodes social
interaction and promotes reinforcement learning through social
prediction error.

Nature Neuroscience, 2021; DOI: 10.1038/s41593-021-00972-9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211202113430.htm

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