Sensory Perceptions

Editor's Note: The second installment of this five-part series, on hearing, will appear in the Oct. 1 issue. Freshly cut lilac, fingernails on a chalkboard, just-baked apple pie, satin and silk, the vivid hues of a sunset. Such sensory stimuli shape people's lives. They arouse and change, elate or sadden, calm or agitate. They tap memories of yesterday or years ago. Information that travels through the eyes, nose, ears, mouth, and skin define the world: what the senses don't perceive, the brain will never know. René Descartes, the famous 17th century French mathematician, philosopher, and physiologist, postulated that all information reaches the brain through the senses. He has since been proven correct: all sensory cues do end up there, arriving as electrical impulses in nerve fibers. But understanding how this happens and how this process can be manipulated is still being decoded. "At some level, everyone who works on the senses is wrestling with the same question: What is the brain doing to transform the environment into an internal picture of the world?" explains neuroscientist Cori Bargmann, University of California, San Francisco, who studies olfaction in the Caenorhabditis elegans worm. "But researchers are trying to get at that question through different avenues, so we're always comparing and contrasting results from different senses." The mapped human and mouse genomes, and advances in molecular biology, are catapulting senses research. With these new concepts and tools, scientists can focus on the specific genes and proteins within the sensory neurons. Not only is the gleaned information moving scientists closer to understanding the connections between the senses and the brain, but researchers are also learning better how these connections are made over a lifetime. "We certainly know a lot more about the senses than we did a few years ago. But there are still so many huge outstanding questions," maintains Stuart Firestein, professor in the department of biological sciences at Columbia University, New York, who over the years has worked in vision, olfaction and gustation research. There's more to the senses, of course, than just being able to smell the roses and see the stars. "The scientific progress in sensory research not only satisfies our curiosity but also brings aid to those who suffer sensory pathologies," says psychologist Linda Bartoshuk, Yale University School of Medicine, who specializes in taste research. "Loss of a sense disrupts the information that we need to interact with our environments, but even worse, it disrupts the information we need to interact with each other." The loss of a sense, she says, "can rob us of pleasure and diminish the quality of our lives." This issue of The Scientist starts a series of articles on some of the most intriguing research occurring on the senses. The first story, on vision, examines how investigators are using gene therapy and stem cell transplantation to move further toward a cure for blindness. Look for articles on the other four senses in upcoming issues. The hearing article will review the ongoing effort to replicate the avian method of hearing regeneration into human hearing regeneration, and what can be expected once that goal is achieved. The story on touch will explore the latest findings on pain, and how this data could be mined for new, better therapeutic treatments. With taste, an explosion of research in the past few years has led to the first identification of the sweet and bitter taste receptors, and is beginning to reveal the complex inner workings of the taste cells. And finally, olfaction researchers are mining interactions between the molecular biology of odors and how they affect innate behaviors.

Sensory Perceptions

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