We may not think about it, but one person threatening another is quite a common thing. A lot of us have been threatened too. However, science did not know how memories of such negatvie social interactions are retrieved. In other words, there was a long-standing question – is there a mechanism behind observing social threat interactions and retrieving them from memory. Now research from the RIKEN Brain Science Institute in Japan has answered that question – there is, in fact, a complex structure of a neural network for this cause.
Scientists have used large-scale neural recording and big data analysis in monkeys to enable a first glimpse of the brain remembering and recalling the memory of threatening social interaction. It helped them to answer a question that has been bothering science community for quite some time – can memory of an observed social encounter be formed and recalled via the same neural pathway.
Researchers used 128-channel large-scale recording array overlaid on a monkey cortex to record electrical activity while the subject watched videos of one monkey threatening another. To establish a difference between reactions to threatening and non-threatening interactions, scientists showed non-threatening interactions to a control group.
Data recorded during the experiment was analysed using Big Data analytical techniques to calculate a multidimensional value called ERC (Event Related Causality). ERC was used to index the continuous evolution of brain activity in time, space, and the direction of communication between brain areas during the time monkeys were watching the videos.
When data was collected, the ERC was decomposed in order to identify hotspots of network activity. These hotspots, called “modules” by the research team, pinpointed specific epochs in the observed social threat interactions. Although methodology of this research was very complex and hard to explain to common public, results are rather interesting.
These so-called modules showed that there is a rich dynamic flow of information in the brain network at unprecedented resolution. One of these modules served to encode the formation of a memory of the observed social interaction. It revealed a flow of information from sensory perception areas to higher brain structures.
When animals were presented with the cues that were observed in the initial threat encounters, while the threatening monkey was hidden from view, study revealed that the same network works in this case too, but with reversed communication flow. This suggests that the same network is used to perceive and recall the threatening social interaction.
These results of the research are rather important as they allow scientists to take a look at the structure of brain networks for cognitive processes such as observing the behaviour of others. The complex methodology used in the study can be used to investigate other situations that require mental processing.
The results are also rather significant for the mapping of brain activity by large federal brain projects including the US BRAIN initiative and EU Human Brain Project, because this study shows that technologies measuring brain activity should not be aimed to monitor large populations of neurons only, but could also serve to research their network communication structures also. However, researchers do not name what will be next steps for the research and whether human social interactions and memories about them could be analysed using the same techniques.