Voltage-Sensitive Dyes and Functional Activity in the Olfactory Pathway

Many of the difficulties encountered in studying how information is handled in the CNS relate to problems with observing and characterizing activities oflarge numbers of neurons, yet it is undoubtedly the interactions between multitudes of cellular elements that underlie the complexity of processing in neuronal circuits. One of the greatest challenges facing the study of circuitry function, then, is to be able to observe the anatomical and physiological characteristics of many cells simultaneously in minute detail. The large numbers and great diversity of neurons, the segregation of processing functions within them, and the enormous complexity of their interconnections require methods that permit simultaneous observations to be made from many neuronal sites with high spatial and temporal resolution. This review summarizes results obtained with voltage-sensitive dye re­ cording, a method having good spatial and temporal resolution for observ­ ing distributed neuronal activity, as it has been applied to the olfactory pathway. Since spatially and temporally distributed activity patterns appear to be basic components of odorant encoding, the olfactory system has been useful for analyzing general mechanisms, possibly rei event to other brain regions, by which such patterns might carry information. In the present review we describe results obtained with voltage-sensitive dye