Smells

The sense of smell can distinguish thousands of odours. Scientists have ide ntified a large family that they believe codes for odour binding sites in t he olfactory lining of the nose. This family of related proteins that may c ouple to a common intracellular second messenger system, combined with the chemists' almost limitless collection of fragrance compounds, is a rich vei n for future mining in the olfactory bulb, information form these receptors is organised into patterns that the brain may interpret as different odour s. Psychophysiological experiments suggest that in the olfactory world of t he brain, there exists a multidimensional odour "space" that characterizes odorous stimuli. Recent studies begin to shed light on the specificity of i ndividual olfactory receptors and demonstrate their ability to mediate the detection of odorous stimuli in vivo, paving the way for a clearer definiti on of the odour space. Thus, the pharmacologist may finally be able to join forces and decipher the code with which the brain determines the identity of simple and complex odorous stimuli. These and other discoveries are lead ing to important insights into human behaviour and providing hope for treat ing those with a diminished or lost sense of smell.