Intracellular Voltage-Sensitive Dyes for Studying Dendritic Excitability and Synaptic Integration
Intracellular voltage-sensitive dyes are used to monitor membrane potential changes from neuronal compartments not readily accessible to glass electrodes, such as basal dendritic segments more than 140 μm away from the cell body. Optical imaging is uniquely suitable to reveal voltage transients occurring simultaneously in two or more dendritic branches, or in two or more locations along the same dendritic branch (simultaneous multi-site recordings). Voltage-sensitive dye recordings can be combined with bath application of drugs that block membrane conductances as well as with focal application of neurotransmitters. The results of dendritic voltage-sensitive dye measurements are naturally incorporated into computational models of neurons with complex dendritic trees. The number of model constraints is notably heightened by a multi-site approach. An interaction between multi-site voltage-sensitive dye recording (wet experiment) and multicompartmental modeling (dry experiment) constitutes one of the most insightful combinations in quantitative neurobiology. This chapter discloses disadvantages associated with voltage-sensitive dyes. It brings useful information for deciding whether voltage-sensitive dye imaging is an appropriate method for your experimental question, and how to determine if a student is ready to work with intracellular voltage-sensitive dyes. Our chapter describes the most important, previously unpublished, practical issues of loading neurons with voltage-sensitive dyes and obtaining fast optical signals (action potentials) from thin dendritic branches using equipment at half price of a standard confocal microscope.
Key wordsElectrochromism Chromophores Hemicyanine Styryl dyes Action potential Dendritic spike Backpropagation Plateau potential Fluorescence and membrane potential
We are grateful to Leslie Loew for comments. Supported by institutional Health Center Research Advisory Council (HCRAC) grant and NIH U01 grant to SDA.
- 16.Canepari M, Popovic M, Vogt K et al (2010) Imaging submillisecond membrane potential changes from individual regions of single axons, dendrites and spines. In: Canepari M, Zecevic D (eds) Membrane potential imaging in the nervous system: methods and applications. Springer Science + Business Media, LLC., New York, NYGoogle Scholar