1. Axon-carrying dendrite cells
Cortical principal neurons receive multiple synaptic inputs at their dendrites and transmit them to the soma and axon. The classical view poses that integration of these inputs occurs in the soma, before a decision about generating an output signal (action potential) is taken at the axon initial segment. Work during the past decades has shown that dendrites play a much more active role in signal amplification and modulation than previously thought.
We are thrilled by yet another extension of the classical model: We recently found that axons of hippocampal pyramidal neurons frequently (~50 %) emerge from a basal dendrite instead of from the soma. We have shown that that this axon-carrying dendrite provides a privileged channel for excitatory synaptic input which is largely independent from perisomatic inhibition (Thome et al., 2014).
Currently, we are investigating the differences in information processing and involvement in memory processes between neurons with and without an axon-carrying dendrite. This project is supported by the DFG (https://gepris.dfg.de/gepris/projekt/427956063).
We use state-of-the-art techniques to observe the activity of defined neurons in freely behaving mice. We have developed new data acquisition and synchronization tools for integration of multi-modal physiological data (e.g., from UCLA Miniscopes, Intan data acquisition, different Cameras, automatic gate control in behavioral test mazes). The code is open source and can be downloaded from GitHub (https://github.com/bothlab).
2. Mechanisms of the generation of different network oscillations
Cortical networks exhibit different characteristic oscillations that are distinctly visible during different behavioral states (e.g. exploration, resting immobility, sleep). We investigate how such different oscillation patterns can be generated by one and the same network. How doe external inputs affect those oscillations, and how do the oscillations, in turn, affect the function of single neurons?
This project has been supported by the DFG (https://gepris.dfg.de/gepris/projekt/351649465) and will be continued.