Schematic diagram of the FCL optogenetic stimulation system. (a) The components of the FCL optogenetic stimulation system include real-time PCR, an optical fiber, an LED light source, and the control software. The real-time PCR continually monitors the expression of target genes, and the control software automatically adjusts the LED light stimulation based on the expression data to precisely control the target gene expression. (b) The basic principle of the FCL system is to use real-time PCR to monitor the expression of target genes and then use the control software to adjust the LED light stimulation in real time to precisely control the target gene expression.