Recording of visual responses in an intact animal. (A) X. laevis tadpole. (B) Diagram of the Xenopus visual circuit. Optic tectal neurons receive direct visual input from retinal ganglion cells of the eye. (C) Experimental setup. Visual stimulation was delivered with a green LED pigtailed to an optic fiber that illuminates the entire eye for whole field stimulation. The tadpole brain was cut along the midline to expose the cell bodies. Visual responses from tectal neurons contralateral to the stimulated eye were recorded by whole-cell recording. (D) Visual responses of tectal neurons. Tectal neurons respond to transient light intensity change. The OFF responses induced by light off is normally bigger in amplitude and longer in duration than ON responses induced by light on. Superimposition of 20 consecutive responses (gray) and the averaged trace (black) are shown. Adapted from . dnIR, dominant negative insulin receptor; moIR, morpholino-mediated knockdown of insulin receptor; wtIR, wild-type insulin receptor.