RT - Journal Article T1 - Modeling and study of Rhodopsin proteins responses to laser light irradiance in ultrafast optogenetic control JF - opsi YR - 2018 JO - opsi VO - 24 IS - 0 UR - http://opsi.ir/article-1-1455-en.html SP - 569 EP - 572 K1 - Optogenetic K1 - Opsin K1 - Spike K1 - Photocycle model K1 - Hodgkin and Huxley model K1 - Ultrafast AB - Optogenetics is a combination of genetics and light delivery systems that can be used for exciting or silencing subpopulations of neurons, with a high spatiotemporal precision. Channelrhodopsins-2 (ChR2) are a class of light sensitive proteins that can drive spiking with millisecond precision to regulate neural activity. There are several properties for this protein that have limited the precision of optogenetic control. For example, many cells can not follow ChR2-driven spiking above the gamma (~40 Hz) range in sustained trains. In this paper we simulated photocurrent kinetics of new variants of ChR2 such as ChRwt and ChETA based on Hudgkin-Huxley model in hippocampal pyramidal cell model with various optostimulation protocols. Obtained results show that functionality both of ChRwt and ChETA is the same and with each optical pulse stimulation there is a neural firing spike. But because of limitation in mechanism of ChRwt at high light-pulse frequencies (50-200 Hz), there is extra spikes as well as pike failure in prolonged illumination. Other fast opsins such as ChETA would enhance the efficacy of optogenetics experiments by evoking one action potential per light pulse, in addition to establishing stable spikes in prolonged illuminations. LA eng UL http://opsi.ir/article-1-1455-en.html M3 ER -