The brain performs its computations based on information from the sensory organs. If this input changes, for instance after an injury, the brain has the ability to adapt. Ideally, after the disturbance has passed, the brain`s processing returns to normal state. Recent studies show that not only the general processing capabilities but also the detailed neural circuits return to their original state. In addition, the work also demonstrates that new neurons can be functionally integrated - even in the adult brain.
A key function of the brain is to integrate incoming sensory information, and to select the optimal behavior in response to these external cues. The underlying computations in the brain are extremely complex and poorly understood. To address this area of research, scientists use the transparent larval zebrafish as model organism. With the aid of powerful microscopes, scientists can monitor the whole brain activity at single cell resolution in the intact, behaving animal. This helps to understand how neuronal circuit dynamics translate sensory processing into behavioral output.
The brain's wiring diagram is a map of information paths, containing the brain's software. The first wiring diagram of an entire brain (published in 1986) came from the roundworm C. elegans with its few hundred neurons. In contrast, the mouse brain has almost 100 million and the human brain about 100 billion neurons. Nevertheless, today it is no longer unthinkable to obtain at least a mouse brain's diagram. The first step on this path is already made: the development of a preparation with sufficient resolution and contrast. Work on methods for cutting, imaging, and analysis is in progress.
Insects use their sense of smell to find food, mating partners or to avoid danger. Carbon dioxide is an important cue for insects. Interestingly, fruitflies reject it strongly, while mosquitoes use it to find human or animal hosts for blood feeding. CO2 and its detection is a field of active research, because we hope to contribute knowledge to the fight against malaria and other deadly diseases. Certain genes could have played an important role during evolution making mosquitoes attracted and fruitflies repelled by CO2.
Our movements are controlled by nerve cells located in the spinal cord. Before birth, these cells have to be connected with the correct muscles, some of which are situated far away from the spinal cord, like the muscles of the lower leg. To reach their destination, the processes of nerve cells have to cover large distances, growing through different tissues. How do they find their way in this complex environment? Scientists from the Max Planck Institute of Neurobiology use genetic and cell biological methods to study the molecular signals that help the growing nerves navigate through the body.
During development of the nervous system each neuron is generating a long process called axon and several short, widely ramified structures called dendrites. Each of those axons is developing a growth cone from which foot- and tentacle-like extensions are protruding (lamellipodia and filopodia). The neurons are thus able to channel through tissue or contact other nerve cells to build a complete nervous system. Other cells that are contacted by a migrating neuron are leading the way, such that they first bind to the respective neuron and reject it shortly after.