Short infrared (IR) laser pulses on the order of hundreds of microseconds to single milliseconds with typical
wavelengths of 1800-2100 nm, have shown the capability to reversibly stimulate action potentials (AP) in neuronal
cells. While the IR stimulation technique has proven successful for several applications, the exact mechanism(s)
underlying the AP generation has remained elusive. To better understand how IR pulses cause AP stimulation, we
determined the threshold for the formation of nanopores in the plasma membrane. Using a surrogate calcium ion,
thallium, which is roughly the same shape and charge, but lacks the biological functionality of calcium, we recorded
the flow of thallium ions into an exposed cell in the presence of a battery of channel antagonists. The entry of
thallium into the cell indicated that the ions entered via nanopores. The data presented here demonstrate a basic
understanding of the fundamental effects of IR stimulation and speculates that nanopores, formed in response to the
IR exposure, play an upstream role in the generation of AP.
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