To the Editor: There are many approaches for epilepsy control. Among them, electrical approaches like deep brain stimulation (DBS) had been helpful in some severe cases. Despite the advantages of DBS in controlling seizures, there are many side effects attributed to this invasive treatment method. These complications motivate new researches in the field to control epilepsy with fewer side effects. Photostimulation provides an appropriate alternative to electrode stimulation. Light beams can be easily and quickly manipulated to target neurons.1 In photostimulation, neurons can be bidirectionally turned on and off with cell-type specificity, high temporal precision, and rapid reversibility. To satisfy these requirements, the microbial light-sensitive proteins Chlamydomonas reinhardtii Channelrhodopsin-2 (ChR2) and Natronomonas pharaonis (NpHR) have been introduced into neurons.1,2 ChR2 can depolarize neural cells, whereas NpHR acts in opposite way and hyperpolarizes neurons. These two proteins can be activated with two distinctive lights, with more than a 100-nanometer wavelength difference. Hence, these proteins can act together in neurons and may modulate neuronal activity. Both proteins have fast temporal kinetics, making it possible to drive reliable trains of high-frequency action potentials in vivo.3 Because NpHR remains active for many minutes when exposed to continuous light and deactivates quickly when light is turned off, it can be used in epilepsy.