Optical stimulation of visual cortex with pulsed 620-nm red light

To explore the optical neural stimulation with visible light, 620-nm red light pulse emitted by LED was used to stimulate the left primary visual cortex of adult rat. The neural response in right primary visual cortex was recorded with a flexible microelectrode. By synchronized averaging the raw signal, optical evoked potentials (OEPs) were observed a negative wave and positive wave after optical stimuli. Furthermore, the amplitude and occurrence of the negative and positive wave were modulated by the strength and pulse width of the optical stimulus. The preliminary experiment suggested that, beyond the infrared laser, the pulse of visible light (e.g. red light) can modulate the neural activity in central nervous system.