Small but mighty – this is probably the most apt description of the cerebellum. Despite weighing just 150 grams and sitting inconspicuously at the back of the human head, it has a very prominent function. It contains 80 per cent of the nerve cells and is not only responsible for motor skills and partly for cognition, but is also involved in processing emotions.

 Of particular interest to Prof Dr Melanie Mark from the Ruhr University Bochum and ELH-PI Prof Dr Dagmar Timmann from the University of Duisburg-Essen - both from the Collaborative Research Centre 1280 - is how the cerebellum contributes to learning, but also to the extinction of conditioned fear reactions. To this end, the two scientists are providing experimental evidence for this in both humans and mice.

 While Prof Mark is conducting research on mice, Prof Timmann's research group frequently uses the 7 Tesla MRI at the ELH to study the human  cerebellum. Over the course of several days, test subjects are conditioned with small electric shocks to react to certain signals with fear, and then to unlearn them again during the following days. With the help of functional MRI (fMRI), it is possible to visualize the extent to which the cerebellum is active during these moments. Prof Timmann has been able to show that the cerebellum plays an important role in the learning and unlearning of fear.

 Another interesting result is this: in cerebellar diseases such as ataxia, for example, test subjects took slightly longer to fear conditioning, but were not as impaired as initially expected. The scientists now suspect that other parts of the brain might step in when the cerebellum is impaired:

 "This is desirable from an evolutionary perspective. If one region fails, the entire neuronal circuit does not immediately collapse. That doesn't mean that the cerebellum is not involved," explain Mark and Timmann.

Read the full article here [Link].

Photo: Roberto Schirdewahn