1. A waveguide neural interface device, comprising: a neural device implantable in tissue and including an array of electrode sites that electrically communicate with their surroundings, wherein the array of electrode sites includes at least one recording electrode site; and a waveguide formed separately from and coupled to the neural device, wherein the waveguide carries light along a longitudinal axis and includes a light directing element that redirects the carried light from the waveguide to illuminate selectively targeted tissue; wherein at least a portion of the redirected light is directed laterally away from the longitudinal axis; and wherein the recording electrode site is configured to sample illuminated tissue.