Dr. Stuart Firestein is the Chair of Columbia University's Department of Biological Sciences. His colleagues and he study the vertebrate olfactory receptor neuron as a model for investigating general principles and mechanisms of "signal transduction" — the ways in which chemicals, such as neurotransmitters, hormones, and peptides with membrane receptors, exert their influence in the brain and nervous system. He hypothesizes that the olfactory neuron is uniquely suited for these studies since it is designed specifically for the detection and discrimination of a wide variety of small organic molecules, i.e. odors.