RELATIONS BETWEEN DIFFERENTIAL THRESHOLD AND SUGAR RECEPTOR MECHANISMS IN THE BLOWFLY

Studies of differential thresholds (.DELTA.I) of the blowfly in response to sucrose have been conducted at behavioral and neurophysiological levels. There is a close correspondence between these 2 and also with .DELTA.I calculated from published data on receptor potential and receptor enzyme activity. This close correspondence among the .DELTA.I, expressed as Weber fractions. (.DELTA.I/I), at all 4 functional levels suggests that the coding mechanism for differential thresholds derives from, or is inherent in, the mechanism of transduction of the receptor membrane and that, for the fly, no complex intervening mechanisms need to be postulated. These results are discussed in relation to differential thresholds of rats.