Sensory Mechanisms in Nematodes

There have recently been unprecedented advances in our knowledge of senses and responses in nematodes. As this review is being published data on sensory mecha­ nisms in nematodes continue to flood in from laboratories all over the world. Developments have not come directly from electrophysiology, but rather indirectly, through detailed neuroanatomy and through interpretations based on the behavior of the entire organism. Studies of the free-living bacteriophagous species Caenorhab­ dill's elegans have led to many of these advances and are the basis for a major part of this review. Caenorhabditis elegans, the subject of a classical study by Nigon (51), was used as a metazoan model for various biological studies by Dougherty & Calhoun (26). Although C elegans and the closely related C briggsae had become familiar, they were little studied until the late 1960s and 1970s. C elegans and C briggsae are now used as models for physiology (7), gerontology (67), genetics (3, 24, 30, 64), and behavior ( 1417, 27-30, 53, 58). During the late 1960s and early 1970s, Dr. Sydney Brenner selected C elegans to explore the genetic basis of behavior. In 1974 Brenner (3) wrote, Behaviour is the result of a complex and ill-under­ stood set of computations performed by nervous systems and it seems essential to decompose the problem into two: one concerned with the question of the genetic speciation of the nervous systems and the other with the way nervous systems work to produce behaviour. Both require that we must have some way of analysing the structure of the nervous ·system. While C elegans is now studied all over the world, the inspiration for these studies and the direction of the current work comes from Dougherty and more recently from Brenner. Details of laboratory handling of C elegans, mutagens, storage, and culturing are available (3, 30). The fundamental objectives outlined by Brenner have not yet been met but the results achieved so far are of critical importance in the study of nematode behavior.