TY - JOUR T1 - Simultaneous sodium and calcium imaging from dendrites and axons JF - eneuro JO - eneuro DO - 10.1523/ENEURO.0092-15.2015 SP - ENEURO.0092-15.2015 AU - Kenichi Miyazaki AU - William N. Ross Y1 - 2015/10/14 UR - http://www.eneuro.org/content/early/2015/10/14/ENEURO.0092-15.2015.abstract N2 - Dynamic calcium imaging is a major technique of neuroscientists. It can reveal information about the location of various calcium channels and calcium permeable receptors, the time course, magnitude, and location of intracellular calcium concentration ([Ca2+]i) changes, and indirectly, the occurrence of action potentials. Dynamic sodium imaging, a less exploited technique, can reveal analogous information related to sodium signaling. In some cases, like the examination of AMPA and NMDA receptor signaling, measurements of both [Ca2+]i and [Na+]i changes in the same preparation may provide more information than separate measurements. To this end we developed a technique to simultaneously measure both signals at high speed and sufficient sensitivity to detect localized physiological events. This approach has advantages over sequential imaging since the preparation may not respond identically in different trials. We designed custom dichroic and emission filters to allow the separate detection of the fluorescence of sodium and calcium indicators loaded together into a single neuron in a brain slice from the hippocampus of Sprague Dawley rats. We then used high intensity light emitting diodes (LEDs) to alternately excite the two indicators at the appropriate wavelengths. These pulses were synchronized with the frames of a CCD camera running at 500 Hz. Software then separated the data streams to provide independent sodium and calcium signals. With this system we could detect [Ca2+]i and [Na+]i changes from single action potentials in axons and synaptically evoked signals in dendrites, both with submicron resolution and a good signal to noise ratio (S/N).Significance Statement: Dynamic imaging is an important technique of neuroscientists. It can reveal information about the location and activation of various channels and receptors, the time course, magnitude, and location of intracellular ion concentration changes, and, indirectly, the occurrence of action potentials. Most experiments exploit [Ca2+]i changes, but measurements of [Na+]i changes, a less exploited technique, can reveal analogous information related to sodium signaling. We developed a technique to measure both signals simultaneously at high speed and sensitivity from localized regions of individual neurons in brain slices. With this method we can measure and analyze aspects of dendritic and axonal physiology that could not easily be determined from measurements of sodium or calcium changes separately. ER -