Gastvortrag von Amiram Grinvald (Weizmann Institute, Israel)Multi modality wide-field optical imaging of Electrical activity
There are many types of powerful optical imaging techniques facilitation new capabilities which never existed before. Here I will review wide-field optical imaging based on continuous illumination provided by Tungsten halogen lamp or strong led illumination and a microscope like imaging system. With a wide-field imaging system we were using macroscope providing magnification of 0.3 to 3 fold, imaging an area of ~ 3x3mm to 25x25mm. With a magnification of 1 the collection efficiency of fluorescence is 100 fold better than that obtained by a microscope objective.
Two types of measurements are used reflection measurements and fluorescence measurements. With reflection measurements one can monitor activity dependent signals based on hemodynamic changes like blood oxygenation, volume and flow changes as well as light scattering changes referred to as intrinsic signal, which are slow (rise-time of 1-3 sec). Using the fluorescence mode one can monitor slow activity dependent change of intrinsic NADH or Flavo protein located at the mitochondria, which can provide better spatial resolution relative to hemodynamic signals. Extrinsic fluorescence probes include either organic or genetically engineered probes sensitive to Ca+2, Na+, and Voltage sensitive dyers. Only the later probes offer sub millisecond response time necessary for real-time monitoring of neuronal dynamics.
These two modalities of optical imaging have been used in all the model preparations used in neuroscience for dissociated cell cultures, explants, invertebrate ganglia, brain slices, drosophila, rats, mice, gerbils, cats, tree shrew, monkeys of many type and human during neurosurgery.
Wide field Optical imaging can be integrated with microelectrodes, dye injection, optogenetic stimulation, electrical stimulation, or two-photon imaging.
Amiram Grinvald is woking at the Department of Neurobiology, the Weizmann Institute of Science, and Optical Imaging LTD 76100 Rehovot, Israel.
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