title: Photoactivation of neurons by laser-generated local heating.
abstract: We present a method for achieving temporally and spatially precise photoactivation of neurons without the need for genetic expression of photosensitive proteins. Our method depends upon conduction of thermal energy via absorption by chemically inert carbon particles and does not require the presence of voltage-gated channels to create transmembrane currents. We demonstrate photothermal initiation of action potentials inHirudo verbananeurons within an intact ganglion and of transmembrane currents inXenopusoocytes. Thermal energy is delivered by focused 50 ms, 650 nm laser pulses with total pulse energies between 250 and 3500 μJ. We document an optical delivery system for targeting specific neurons that can be expanded for multiple target sites. Our method achieves photoactivation reliably (70 - 90% of attempts) and can issue multiple pulses (6-9) with minimal changes to cellular properties as measured by intracellular recording. Direct photoactivation presents a significant step towards all-optical analysis of neural circuits in animals such asHirudo verbanawhere genetic expression of photosensitive compounds is not feasible.
authors.affiliation: Department of Physics, University of California, San Diego. 9500 Gilman Drive, La Jolla, CA, 92037, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Migliori
authors.affiliation: Department of Physics, University of California, San Diego. 9500 Gilman Drive, La Jolla, CA, 92037, USA.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Di Ventra
authors.affiliation: Department of Neuroscience, University of California, San Diego. 9500 Gilman Drive, La Jolla, CA, 92037, USA.
authors.forename: William
authors.initials: W
authors.lastname: Kristan
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