BFNT-Symposium: Perspectives in Neurotechnology
23.06.2009 16 c.t.
Holographic optical microscope to mimic neuronal excitation patterns
by Dr. Christoph Lutz
from Neurophysiology and New Microscopy Laboratory, Université Paris Descartes, France
Seminarraum Haus 2, 4. Stock (Bunsenstr.)
We have developed a holographic photolysis microscope based on the use of a nematic liquid crystal spatial light modulator (LC-SLM). The SLM permits modulating the wave front of the laser light used for photolysis excitation. This system is capable of generating excitation spots of variable size and number, and illumination patterns shaped to precisely match fine cellular processes. Combining holographic photo-activation with single cell electrophysiology, we used shaped illumination and simultaneous multi spot illumination to elicit responses to photolysis of caged glutamate from different types of neuronal cells in brain slices.
To precisely evaluate the photo-activation volume for different illumination patterns, we designed an algorithm to calculate the excitation light distribution around the objective focal plane. We found, and verified experimentally, that the use of holographic beams allows a better optical confinement with respect to a focused Gaussian laser beam. In conclusion, our theoretic and experimental results underline the possibility of precisely controlling the excitation volume with a SLM. Our method opens the fields to adaptive photo-activation techniques where the excitation volume can be rapidly tailored to the experimental context.
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