The tractability of light activated receptors makes them attractive tools by which to study the brain. They allow for the non-invasive and specific control of neuronal signaling and could allow for the study of receptor pathways that occur faster than the rate of diffusion. Furthermore, with the aid of implantable light devices light activated receptors have the potential for use in live animals and later in humans to control and cure GPCR pathways involved in diseases. We demonstrate here the use of vertebrate rhodopsin to control ion channel modulation, spinal cord, cerebellar and serotonergic signaling via activation of the pertussis toxin sensitive Gi/o pathway by light.