Labellar lobe spreading in the blowfly: Regulation by taste and satiety

Summary Lobe spreading behavior was studied by recording electromyograms from the muscles which spread the labellar lobes, the retractors of the furca (RF) inPhormia regina. RF responses and lobe spreading could be elicited by stimulating labellar, but not tarsal, taste hairs with sucrose (Fig. 3). RF activity was important to spread the lobes at the beginning of a meal, but was not necessary for continued feeding (Fig. 4).Temporal summation between sugar receptor spikes was necessary to elicit RF responses. Central response decrement occurs independently for different labellar hairs and may participate in the termination of motor responses.RF responses were more probable and more intense when either the sucrose concentration of the stimulus or the number of hairs stimulated was increased (Fig. 7). Stimulation with NaCl had no effect on the response to simultaneous sucrose stimulation of other hairs (Table 1).Feeding caused decreases in the probability and intensity of motor responses, but did not alter chemosensory responses (Figs. 8 and 9). Section of either the recurrent or median abdominal nerves prevented this postingestional inhibition of lobe spreading (Fig. 9).These results are discussed with regard to the possible role that regulation of lobe spreading may play in the control of food intake.This work was supported by United States Public Health Service Training Grant 5T01 GM 00457-13S2 and by a grant from the National Science Foundation to Dr. Vincent G. Dethier. I wish to thank Dr. Dethier for his support and encouragement.