Wide-eyed with fear, or how we learn to be afraid through observation

A surprising amount of the information we have comes not from our own experience but from our observation of other people. This is possible because their emotions and behaviours serve as a source of valuable clues about the environment. The ability to learn through observation is widespread in the animal kingdom; we can observe it in our close and distant relatives, the apes, but also in rodents, mice and rats.

Photos: One HD for FNP Our research project aims to investigate the mechanisms of human observational learning with the use of observational fear conditioning. In the process, one person is asked to watch another undergo the classical conditioning procedure, during which subjects learn to associate a given stimulus (e.g. a blue square on the computer screen) with an aversive event (a weak but unpleasant electric shock). After a certain time, the sight of the blue square elicits unpleasant sensations even when it is no longer accompanied by an electric shock. We are interested not so much in the process of direct learning about the meaning of the blue square from one‘s own experience, as from the observation of another person, i.e. a process based only on social stimuli, such as facial expressions.

Our experiments showed that socially transmitted fear can cause a clear physiological response in observers. Interestingly, not all subjects learned to associate the shock with the blue square. This suggests that observational conditioning rests on two independent mechanisms: the perception of the emotion experienced by another person and its conscious association with the co-occurring stimulus.

Our fMRI studies showed that the brain regions of key importance for direct fear conditioning were also activated by socially transmitted fear. In particular, we observed enhanced activity in the amygdala, the anterior insula and the anterior cingulate cortex. We also looked at brain activation patterns to see if they depend on whether the subject witnesses a friend or a stranger who experiences fear. No substantial differences in brain activation were observed in this case, which suggests that what observation does, above all, is provide information: what matters is the knowledge of danger and not where the knowledge comes from. A similar brain activation pattern and its independence from the degree of familiarity were also observed in rodents, which suggests the evolutionary continuity of the phenomenon.

Experiments on rats demonstrated that they can gauge the intensity of fear in other animals and use that information to adapt to the environment. If the observed rat is very afraid, other animals will show a freeze or flight response to evade direct danger. On the other hand, if the rat is less afraid, they will begin to survey the surroundings for possible threats. These reactions are mediated by the amygdala, and in particular the central amygdala nucleus. Its links to the anterior cingulate cortex and the insular cortex, as well as the basolateral amygdala, and plays a key role in socially transmitted fear. Research on animals allowed us to stimulate and inhibit specific neuronal circuits and thus understand their function. Initially, this line of research, which later split into several projects, was funded under the OPUS 6 call. Entitled “Neuronal circuits of the central amygdala nucleus involved in social fear transmission”, the project allowed us to collect preliminary data and apply for an ERC grant. The ERC Starting Grant then covered my research on rodents, the findings of which have recently been published in “Current Biology” (Andraka, Kondrakiewicz et al., 2021, 31, 2347–2358; https://doi.org/10.1016/j.cub.2021.03.047), attracting the interest of the scientific community, as evidenced by a guest commentary in the same journal (Keysers & Gazzola, Current Biology, 31, R728-R730; https://doi.org/10.1016/j.cub.2021.03.100). The results of the OPUS 10 project described above, which compared rodents and people, are currently pending publication.

The research team includes: Dr hab. Ewelina Knapska, professor of the Nencki Institute, Mgr Anna Kaźmierowska, Mgr Michał Szczepanik, Dr Marek Wypych, Dr hab. Jarosław Michałowski, professor of the SWPS University, Dr hab. Artur Marchewka, professor of the Nencki Institute, and Professor Andreas Olsson, Karolinska Institutet.