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Abstract #2881

The Influence of Laser Power and Pulse Characteristics on the Optogenetically Induced BOLD Signal of Excitatory Neurons in the Mouse Hippocampus at 9.4T

Philipp Lebhardt1, Wolfgang Kelsch2, 3, Claudia Falfan-Melgoza1, Gabriele Ende1, Alexander Sartorius2, Wolfgang Weber-Fahr1

1NeuroImaging, Central Institute of Mental Health, Mannheim, Germany; 2Clinic of Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany; 3Cinical Neurobiology, University of Heidelberg, Hiedelberg, Germany

In this study we were interested in the influence of laser power and stimulation frequency on the optogenetically induced BOLD signal of the hippocampal network in mice. We induced expression of channelrhodopsin-2 in Ca2+/calmodulin-dependent protein kinase II-expressing neurons by virus injection. Laser stimulation was periodically applied through an optical fiber in the left hippocampus with block and event related designs using different power and stimulation characteristics. We found activation and deactivation due to laser heating effects even at low power levels and diverse activation patterns in dependency of stimulation length and frequency