Pulses of blue light can alter the behavior of rhesus monkeys by activating particular neurons in the brain, according to research led by investigators at Massachusetts General Hospital in Boston and the Massachusetts Institute of Technology in Cambridge (Gerits A et al. Curr Biol. 10.1016/j.cub.2012.07.023 [published online July 26, 2012]).
In optogenetics, neurons are made responsive to light through the insertion of light-sensitive genes. Many optogenetic studies have been conducted in invertebrates and rodents.
Hampton T. Light Pulses Activate Neurons. JAMA. 2012;308(9):853. doi:10.1001/2012.jama.10871