Professor Dr Tobias Bonhoeffer

Research Priorities: Plasticity of the brain, neural circuits, learning and memory, prefrontal cortex
Tobias Bonhoeffer is a German-American neurobiologist whose research has significantly contributed to the understanding of learning and memory forming. He was able to show that synapses – the contact points between nerve cells – are formed, strengthened, weakened or broken down over the course of life. This synaptic plasticity forms the basis of all life. Tobias Bonhoeffer’s insights are relevant for both basic research as well as applied neurosciences.
Learning takes place at the synapses between nerve cells. Tobias Bonhoeffer and his team have shown that these connections in the brain are not static and instead adapt themselves to changing requirements. In this way Tobais Bonhoeffer’s working group was able to demonstrate that the strengthening of a synapse often correlates with the growth of dendritic spines – tiny structures that act as “docking points” between nerve cells. These insights verify the connection between synaptic function and structural plasticity.
Tobias Bonhoeffer’s team has also researched neural plasticity on a molecular level and revealed the role of nerve growth factors. The brain-derived neurotrophic factor (BDNF) supports the growth and stability of synaptic connections and is a crucial determinant for long-lasting synaptic changes. Further work has shown that the stability of synaptic contacts during learning also depends on the breakdown of specific proteins rather than synthesis alone.
Another result of Tobias Bonhoeffer’s research is the discovery that synaptic contacts formed during learning can also continue to exist when the learned information is forgotten. These “latent traces” facilitate the later re-learning of the content. This explains why skills acquired early in life can be more easily reacquired.
The neurobiologist also analysed cortical maps, particularly in visual systems. In early studies he demonstrated, using intrinsic optical imaging, the existence of “pinwheels” – radially arranged patterns of neural activity in the visual cerebral cortex of mammals. These maps are both stable and flexible enough to adapt themselves to experiences from the environment. In an earlier study the research team was able to prove that rodents can sort visual stimuli into categories. Specific changes in the medial prefrontal cortex play a key role in this. These results emphasise the importance of this cerebral area for complex cognitive processes.
Tobias Bonhoeffer’s research shows how neural networks are formed by interactions with the environment. His work on synaptic plasticity and cortical maps make clear that learning influences both the brain’s function and structure. These insights have informed basic research and also offer potential for treatment approaches, for example for rehabilitation after brain injuries or for treating neurodegenerative diseases.