Laboratory of Experimental Neurophysiology
Department of Neurosurgery
University of Bonn Medical Center
D- 53105 Bonn
Phone +49 (0) 228 287-19224
Fax: +49 (0) 228 287-11718
Classical synaptic transmission from neurons to gial cells
Over the past 10 years, we and others described an unexpected communication between neurons and oligodendrocyte precursor cells: Neurons form classical synapses with these glial cells which are functionally and morphologically indistinguishable from regular synapses between neurons. There are still many open questions about this novel phenomenon but the most important is what is the functional meaning of neuron-glia synapses?
Extracellular glutamate signaling and synaptic transmission
Glutamate as the major excitatory neurotransmitter in the brain is solidely established and the concept of its vesicular release has been coined more than 100 years ago. Based on this it is currently believd that neuronal information in the brain propagates only along distinct circuits, just like the spread of electrical current in computers. However, if we have a close sub-microscopical look at conventional synapses in the CNS, it becomes clear that we actually do not yet know whether neurons are really connected in a 1-to-1 fashion and whether relevant glutamate release only happened from synaptic nerve terminals.
Intracellular Calcium signalling
Calcium ions are the most versatile and important intracellular messengers for neuronal function and we tend to take their multitude of actions for granted. But it is in fact little understood what are the mechanisms preventing indiscriminate activation of calcium-dependent pathways, which would immediately cause neuronal death. We use high resolution calcium imaging and biophysical modelling to explore the spatial and temporal diffusion domains of intraneuronal calcium and what are the mechanisms regulating it.
We are using brain slice preparations combined with 2-photon and conventional laser scanning microscopy to perform complex imaging-, FLIM- and uncaging experiments. In addition we use 2-photon based in vivo imaging, electron microscopy, immunohistochemistry and spectrofluorometric measurements and theoretical biophysical approaches to extend and validate our findings.