Berlin 2012 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 1: Statistical Physics of Biological Systems I (with BP, talks from DY)
DY 1.14: Talk
Monday, March 26, 2012, 13:00–13:15, MA 001
Continuous Dynamic Photostimulation - delivering defined, in-vivo-like fluctuating stimuli with Channelrhodopsins — •Andreas Neef1,3, Achmed El Hady1,2,3, Walter Stühmer2,3, and Fred Wolf1,3 — 1MPI für Dynamik und Selbstorganisation, Göttingen — 2MPI für Experimentelle Medizin, Göttingen — 3BFNT
Central neurons typically operate in a noise driven regime: thousands excitatory and inhibitory synapses give rise to a constantly fluctuating conductance. Its statistic is similar to low-pass filtered white noise conductance that can be parameterized by is average, standard deviation and correlation time. An understanding of action potential (AP) generation and encoding in the noise driven regime requires the detection of AP times during stimulation with defined time dependent conductance. Using a light activated ion channel (ChIEF) under continuously fluctuating illumination, we achieve a defined, reproducible conductance modulation that mimicks the effect of the naturally occurring synaptic inputs. Cultured neurons subjected to this continuous dynamic photostimulation (CoDyPs) generate seemingly random, but reproducible patterns of APs in experiments lasting several hours. The induced conductance waveform can be precisely predicted by convolution of the light signal with the light-conductance transfer function of ChIEF. Together with non-invasive AP detection by extracellular electrodes, CoDyPs lays the foundation for very long-lasting studies of action potential generation in a fluctuation driven regime. This will allow the measurement of dynamical response properties and the respective cut-off frequencies from individual neurons.