A fair reward ensures a good memory

Date:
June 17, 2020
Source:
Universite' de Gene`ve
Summary:
By deciphering the neural dialogue between the brain's reward
and memory networks, a new study demonstrates that the lasting
positive effect of a reward on the ability of individuals to retain
a variety of information.



FULL STORY ==========================================================================
How does our memory work and how can we optimize its mechanisms on a
daily basis? This question is at the heart of many neuroscience research projects.

Among the brain structures examined to better understand
memory mechanisms, the reward system is now at the centre of
investigations. Through the examination of brain activity in healthy
human subjects, scientists from the University of Geneva (UNIGE) have highlighted the lasting positive effect of a reward - - monetary,
in this case -- on the ability of individuals to retain a variety of information. Moreover, and much more surprisingly, the research team demonstrated that the average accumulation of reward should be neither
too small nor too large. By ensuring an effective neural dialogue between
the reward circuit and the memory circuit, this delicate balance allows
the proper encoding of memories in our brain. These results can be read
in Nature Communications.


========================================================================== Empirically, it seems quite logical that obtaining a reward can improve
the memories associated with it. But what are the brain mechanisms at
work, and how can we exploit them to optimize our memory capacity? "The positive influence of a reward on memory is a well-known phenomenon," says Sophie Schwartz, full professor in the Department of Basic Neurosciences
at the UNIGE Faculty of Medicine, who led this work. "However, our
experiment aimed to take a further step in understanding this mechanism
by looking at two important aspects: does the effect last over time and
what role does the accumulation of reward play?" A measured challenge
to motivate the brain To answer these questions, the scientists have
developed an experiment using functional magnetic resonance imaging,
an imaging technique that allows real- time observation of the brain in
action. About 30 healthy subjects were asked to remember associations
between objects and people; each correct answer was associated with points gained, and each incorrect answer with points lost (the points were then converted into money). Twenty minutes later, the subjects were asked
to retrieve these associations to earn additional points. Critically,
the average number of points that could be gained varied over the course
of the experiment.

"Contrary to what one might have thought, the best results were not
associated with the highest accumulation of rewards, the point where
subjects should have been the most motivated," says Kristoffer Aberg,
a researcher now at the Weizmann Institute of Science and the first
author of this work. The most effective? Somewhere between the highest
and lowest accumulated rewards. "Our brain needs rewards to motivate us,
but also challenges," explains Sophie Schwartz. "If the task is too
easy, motivation decreases as quickly as if it is too difficult, and
that affects our ability to encode information. Imagine picking berries
in the forest: if they are everywhere, you do not have to remember where
to find them. If there are only a few, the effort required to pick them
is too great in relation to the possible gain -- a few berries will
not feed us. Now, if clusters of berries are scattered throughout the
forest, remembering their exact location will allow us to pick more in
a short time." A dialogue between brain areas In the brain, memory is primarily managed by the hippocampus, a region of the brain responsible
for encoding and storing memories. When a reward is involved, however,
another region is activated, the ventral tegmental area, which is involved
in the reward system and responsible for the release of dopamine related
to the satisfaction of obtaining a reward. "It is the dialogue between
these two brain areas that helps maintain motivation, improve learning,
and consolidate memories, even over time," explains Kristoffer Aberg.

This experiment shows the importance of motivation in memory and learning,
but also the subtle, and probably individual-specific, balance that
should be instituted. These lessons are particularly useful in the
school environment, with the idea of creating learning contexts that
would foster this motivation according to the needs of children.


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


========================================================================== Journal Reference:
1. Kristoffer Carl Aberg, Emily Elizabeth Kramer, Sophie
Schwartz. Interplay
between midbrain and dorsal anterior cingulate regions arbitrates
lingering reward effects on memory encoding. Nature Communications,
2020; 11 (1) DOI: 10.1038/s41467-020-15542-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200617100418.htm

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