Please note: Fom November 1st, 2010, I am working as a postdoc with Prof. Fritjof Helmchen at the University of Zurich.

New contact data:

Roland Krueppel
Neurophysiology - Prof. F. Helmchen
Brain Research Institute - University of Zurich
Building 55, Winterthurerstr. 190
CH-8057 Zurich
Tel +41 44 63 53392
Fax +41 44 63 53303


 What I am interested in

The hippocampus is a unique structure in the mammalian brain that is involved in spatial navigation and episodic memory. The difficult task of moving in a complex environment requires the generation of a brain-internal spatial map. There are distinct forms of maps present in the hippocampus and adjacent cortical structures. In the entorhinal cortex neurons fire at defined spatial locations which cover the environment in the form of a triangular grid. Place-field neurons in the hippocampus, in contrast, each fire at a specific position in the environment.
The strongest projection from the entorhinal cortex to the hippocampus, the perforant path, targets the granule cells of the dentate gyrus. How does the  map-transformation between the entorhinal cortex and the dentate gyrus work and which neuronal and/or network properties are underlying?
The dentate gyrus has been shown to be the region of the hippocampus most sensitive to small changes in the environment and is thought to perform an operation called pattern-separation. What are the cellular features that enable the dentate gyrus to accomplish this task?
One of the few brain regions that even in adult life continously generate new neurons is the dentate gyrus. Disruption of this process is believed to interfere memory formation in the dentate gyrus. What is the contribution of the newborn granule cells to the dentate gyrus network funtion?

And - what is the dentate gyrus good for anyway?

What I am doing

My actual project deals with information processing in the dentate gyrus...
For this purpose I am developing and using methods to uncover the mysterious ways of the brain:

- Patch-clamp, somatodendritic recordings, two-photon assisted patching of fine dendrites
- Two-photon uncaging
- Two-photon and widefield calcium imaging
- NEURON modelling
- Second-harmonic voltage imaging
- Second-harmonic imaging of microtubules


Drink coffee

What I will do in the future

... hippocampus ... spatial navigation ... rhythm ... in-vivo ...

How all this looks

CA1 oblique dendrite  
 Oblique dendrites of a CA1 pyramidal cell
A CA1 pyramidal neuron in all its beauty
 A CA1 pyramidal cell in all its beauty
A bunch of pyramidal neurons
A mysterious CA3 pyramidal cell with its big mossy fiber synapses
 A mysterious CA3 pyramidal cell with its big mossy fiber synapses
 First steps with optogenetics - a halorhodopsin construct in neuronal primary cultures
Second-harmonic image of ordered microtubules in CA1 apical dendrites
Ordered microtubules in CA1 apical dendrites
 Simultaneous dendritic patch-clamping and second-harmonic voltage imaging
Geometry of second-harmonic generation of dye molecules in cell membranes
 Geometry of second-harmonic generation of dye molecules in a cell membrane
   HOMO and LUMO orbitals of FM4-64 second-harmonic voltage-sensitive dye molecule