CODING OF BLEND RATIOS OF BINARY-MIXTURES BY OLFACTORY NEURONS IN THEFLORIDA SPINY LOBSTER, PANULIRUS-ARGUS

The aim of this study was to investigate quality coding of blend ratio s of binary mixtures by olfactory receptor cells in the spiny lobster. Three odorants (adenosine-5'-monophosphate, L-glutamate, and taurine) at 0.1-100 mu mol . l(-1) and seven blend ratios of each of their bin ary mixtures at a total concentration of 100 mu mol . l(-1) were used. The olfactory cells recorded (n = 48) evoked across-neuron patterns f or single odorants that were well separated from each other. Across-ne uron patterns varied with stimulus concentration but less than with st imulus type. Blend ratios of the three mixtures evoked across-neuron p atterns that were orderly placed within a continuum between those elic ited by the components. Mixture interactions, defined as a lack of ind ependent effects by a mixture's components, occurred in 25, 24 and 37% of responses to blend ratios of glutamate/taurine, adenosine-5'-monop hosphate/taurine, and glutamate/adenosine-5'-monophosphate, respective ly. These mixture interactions did not have a large enough effect on t he across-neuron patterns for the mixtures such they would be novel re lative to those of the single components. These results suggest that d espite mixture interactions the quality of individual compounds is not lost when mixed. This corroborates behavioral studies showing that sp iny lobsters have the ability to elementally process odor mixtures.