Neuroimaging shows that the human hippocampus is involved in quick and successful decisions.


In their everyday life, people are constantly confronted with decision conflicts, especially if they need to suppress an action that would have made sense under normal circumstances. For example, when the pedestrian lights go green, a pedestrian would normally start walking. If a car comes speeding along at the same time, the pedestrian should stay where he is.

Besides its relevance for declarative memory functions, hippocampal activation has been observed during periods of uncertainty and decisive conflict in the person.  Because the hippocampus is essential for memory, researchers speculate about its role in conflict resolution. Now, researchers from the Ruhr-Universität Bochum (RUB), the University Hospital of Bonn as well as in Aachen and Birmingham have demonstrated for the first time that the human hippocampus is also involved in quick and successful conflict resolution. The opensource study is published in the journal Current Biology.

Previous studies in animals show a role of the hippocampus for inhibition of prevailing response tendencies and suppression of automatic stimulus-response mappings. In humans a recent fMRI study demonstrated hippocampal involvement in approach-avoidance conflicts. However, the more general significance of hippocampal activity for dealing with response conflicts also on a cognitive level is still unknown.

In the current study participants heard the words high or low spoken in a high or low tone, and they had to state at what pitch the speaker said them. Results show that if the pitch didn’t correspond with the meaning of the word, a conflict was generated and the participants would answer more slowly and make more mistakes.

The researchers used two different measurement methods to validate that the hippocampus is active in such conflicting situations; this applies particularly when a person solves the conflicts quickly and successfully.  The lab analysed the brain activity in healthy participants with functional magnetic resonance imaging. They also gained the same results in epilepsy patients who had EEG electrodes implanted in the hippocampus for the purpose of surgery planning; this is how the team measured the activity in that brain region directly.

Results show a completely new function of the Hippocampus, the processing of activity conflict.  The team hypothesize that once a conflict has been successfully resolved the memory system then becomes more active to remember the ‘best’ decisions.  In order to answer the question how that function interacts with memory processes, the group state that they will have to carry out additional tests.  They go on to conclude that permanently unsolved conflicts can’t be used for learning helpful lessons for the future.

The lab surmise that according to their model, the brain works like a filter and it responds strongly to resolved conflicts, not to unsolved conflicts.  For the future the researchers now plan to verify this hypothesis in additional studies.

Source:  Ruhr-Universität Bochum (RUB) 

Response Conflict Is Associated with BOLD Signal Enhancement in the Hippocampus. ) Results within a search mask consisting of hippocampus and parahippocampal gyrus. Left: brain activation within the left hippocampus for the contrast correct inconsistent > correct consistent trials. Human Hippocampal Dynamics during Response Conflict. Axmacher et al 2015.

Response Conflict Is Associated with BOLD Signal Enhancement in the Hippocampus. ) Results within a search mask consisting of hippocampus and parahippocampal gyrus. Left: brain activation within the left hippocampus for the contrast correct inconsistent > correct consistent trials. Human Hippocampal Dynamics during Response Conflict. Axmacher et al 2015.

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