Mainly I study the sense of touch and what the molecules are that transduce touch. And I use mutants in the nematode Caenorhabditis elegans to look at that problem.
We know what molecules are needed to sense light - what turns that signal that detects light into an electrical signal. We know how smells are detected. But we have a vast number of senses for which we know what the signal is, but we don't know what the receiver is.