Preference by Association: How Memory Mechanisms in the Hippocampus Bias Decisions

Contributed by gewimmer

G. E. Wimmer and D. Shohamy
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AuthorsG. E. Wimmer and D. Shohamy
DescriptionGroup-level SPM for the contrasts: 1) Reward phase stimulus onset value / stimulus reward prediction error, 2) Reward phase outcome reward prediction error, 3) Reward phase stimulus-stimulus association learning error, 4) Reward phase modulation by subsequent decision bias, 5) Reward phase decision bias PPI connectivity. Paper: Preference by association: how memory mechanisms in the hippocampus bias decisions. Wimmer GE, Shohamy D. Science. 2012 Oct 12;338(6104):270-3. Every day people make new choices between alternatives that they have never directly experienced. Yet, such decisions are often made rapidly and confidently. Here, we show that the hippocampus, traditionally known for its role in building long-term declarative memories, enables the spread of value across memories, thereby guiding decisions between new choice options. Using functional brain imaging in humans, we discovered that giving people monetary rewards led to activation of a pre-established network of memories, spreading the positive value of reward to nonrewarded items stored in memory. Later, people were biased to choose these nonrewarded items. This decision bias was predicted by activity in the hippocampus, reactivation of associated memories, and connectivity between memory and reward regions in the brain. These findings explain how choices among new alternatives emerge automatically from the associative mechanisms by which the brain builds memories. Further, our findings demonstrate a previously unknown role for the hippocampus in value-based decisions.
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Add DateMarch 28, 2017, 10:42 p.m.