Sensory systems.

Research on the senses spans the enormous range from analysis of individual molecules involved in sensory transduction to the attempted elucidation of conscious sensation. Because the variety of conceptual and experimental approaches varies so broadly across the field, it is impossible to delineate a single direction for future research. Two trends are nonetheless apparent. At the reductionistic end of the spectrum, in the analysis of sensory transduction, studies on all the senses will increasingly be driven by the techniques of molecular biology. The advent of techniques for producing cDNA libraries from small ensembles of receptor cells, or even from individual cells, will permit the recognition of new constituents of receptor cells and of factors involved in their specification, differentiation, and maintenance. In the integrative realm of sensory neurobiology, future studies will increasingly rely on optical techniques for the study of activity patterns on the surfaces of sensory areas of the cerebral cortex and on noninvasive functional imaging for the investigation of neural responses in human subjects. These techniques will continue to strengthen our understanding of the relation between neuronal activity and conscious sensory experience.