Emotional responses to pleasant and unpleasant oral flavour stimuli

The hedonic valence of taste perception plays a crucial role in the control of responses related to feeding behaviour. Taste and olfaction perception can induce autonomic responses, such as heart rate variability (HRV), which are involved in the evoked emotional reactions. Analysis of HRV can help distinguish sympathetic from parasympathetic regulation of the sinoatrial node. In this work, we analysed the HRV associated with oral flavour stimuli with opposite hedonic dimension and assessed their sympathovagal balance. ECGs were recorded continuously on 11 men and 12 women before and after stimulations. Experiments were performed in two sessions for comparison. ANOVA highlighted the decreases and increases of sinusal rhythm associated with pleasant and unpleasant flavour stimulations, respectively. Time and frequency domain analysis of HRV indicates that bradycardia induced by the pleasant stimulus can be attributed to an increase in the vagal tone, whilst tachycardia evoked by the unpleasant stimulus denotes a reduction of the vagal tone in women and an increase of the sympathetic tone in men. In conclusion, our data suggest that the HRV analysis may represent a valuable tool for autonomic nervous system response characterization associated to the hedonic dimension of the complex flavour sensations induced by food and/or beverages. © Springer Science+Business Media, LLC 2011

EAG responses to pheromone as a tool in the control of population dynamics of the gypsy moth <i>Lymantria dispar</i>

The reproductive programme of the gypsy moth Lymantria dispar L. (Lepidoptera: Lymantriidae), the most important defoliator of Sardinian Quercus suber L. forests, is based on production and release of its sex pheromone (+)disparlure by calling female moths and its perception by conspecific males. The acquisition of information about any factors influencing male sensitivity to this sex attractant may help improve field techniques against this defoliator or possibly provide a basis for predicting where favourable conditions for control of population dynamics will occur. In this respect, the pheromone might be used as a specific tool for olfaction research and to monitor changes in male sensitivity, thus leading to a better control of population

The gustin (CA6) gene polymorphism, rs2274333 (A/G), is associated with fungiform papilla density, whereas PROP bitterness is mostly due to TAS2R38 in an ethnically-mixed population

PROP responsiveness is associated with TAS2R38 haplotypes and fungiform papilla density. Recently, we showed that a polymorphism in the gene coding for the salivary trophic factor, gustin (CA6), affects PROP sensitivity by acting on cell growth and fungiform papillae maintenance, in a genetically homogeneous cohort. Since population homogeneity can lead to over estimation of gene effects, the primary aim of the present work was to confirm gustin’s role in PROP bitterness intensity and fungiform papillae density in a genetically diverse population. Eighty subjects were genotyped for both genes by PCR techniques. PROP responsiveness was assessed by filter paper method and fungiform papilla density was determined in each subject. As expected, PROP bitterness ratings were lower in individuals with the AVI/AVI diplotype of TAS2R38 than in individuals with PAV/PAV and PAV/AVI diplotype. However, no differences in PROP bitterness among genotypes of the gustin gene, and no differences in the density of fungiform papillae related to TAS2R38 diplotype were found. In contrast, the density of fungiform papillae decreased as the number of minor (G) alleles at the gustin locus increased. In addition, the distribution of TAS2R38 genotypes within each gustin genotype group showed that the occurrence of recessive alleles at both loci was infrequent in the present sample compared to other populations. These findings confirm that papillae density is associated with gustin gene polymorphism, rs2274333 (A/G), in an ancestrally heterogeneous population, and suggest that variations in the frequency of allele combinations for these two genes could provide a salient explanation for discrepant findings for gustin gene effects across population

Analoghi di sintesi del feromone sessuale come strumento per il controllo della popolazione di <i>Lymantria dispar</i>

La strategia riproduttiva delle farfalle notturne è basata sull’utilizzo di un feromone speciespecifico, prodotto dagli esemplari femminili per il richiamo a lunga distanza degli individui maschi conspecifici. In particolare le femmine di Lymantria dispar, uno dei più importanti insetti fitofagi defogliatori delle sugherete sarde, elaborano un feromone costituito da un unico componente, chiamato (+)disparlure (2-methyl-7,8-epoxy-octadecane) e lo accumulano nella ghiandola del feromone fino al rilascio. Nel presente lavoro abbiamo sintetizzato diversi analoghi del feromone naturale, allo scopo di ottenere molecole con un maggiore potere attrattivo sugli esemplari maschili, o più stabili nel tempo, ossia dotate di tempi di decadimento più lunghi

Morphological and electrophysiological mapping of tarsal chemoreceptors of oviposition-deterring pheromone in Rhagoletis pomonella flies

Light microscopy and S.E.M. observations revealed that Rhagoletis pomonella female tarsi, bearing the principal receptors of oviposition-deterring fruit marking pheromone (ODP), have 3 types of chemosensilla: B, C and D. Using electrophysiological hair tip-recording techniques, we found that D chemosensilla located in pairs on distal ventrolateral portions of the 2nd, 3rd and 4th tarsomeres of each leg were highly sensitive to stimulation by the pheromone. D chemosensilla located in pairs on the 5th tarsomere of each leg were moderately sensitive to the pheromone, while the B and C chemosensilla of all tarsi were nearly or completely insensitive to it. For reasons discussed, the D chemosensilla on the prothoracic tarsi may be the most important in providing sensory input eliciting oviposition deterrence. © 1982

Candidate codes in gustatory system of caterpillars

Larvae of tobacco hornworms offer unique opportunities to relate the electrophysiological output of identified chemosensory neurons to specific behavioral responses. Larvae can discriminate among three preferred plants with only eight functioning gustatory receptors. They can be induced to prefer any one of the plants, and these preferences can be reversed. All eight neurons respond to each plant sap. Two fire too infrequently to permit detailed analysis. Analyses of the remaining six show that all electrophysiological responses consist of phasic and tonic components. Only the 'salt best' cell fires during the phasic period. Temporal analysis of the spike train during this period shows that tomato and tobacco could be distinguished from Jerusalem cherry but not from each other by a rate code. Measurements of behavioral response times together with the nonspecificity of this with respect to food plants, unacceptable plants, and sodium chloride eliminate a phasic period rate code as a probable mechanism for complex discrimination. Events occurring in the tonic period, when all cells are firing, suggest a major role for this period. Analyses of variance in the interval frequencies of the large and medium spikes suggest that a variance code could allow discrimination among the three plants as long as both cells were firing at the same time. Evidence has been found for temporal patterning in the tonic response of the 'salt best' cell to Jerusalem cherry but is absent elsewhere. The most likely basis for coding the difference between each of the three plants is across-fiber patterning in which the relative rates of firing and the variances of all the sensory neurons in the tonic phase are critical

Differences in the olfactory sensitivity of Ceratitis capitata to headspace of some host plants in relation to sex, mating condition and population.

The Mediterranean fruit fly, Ceratitis capitata Wied., is among the most serious pests in horticulture worldwide, given to its high reproductive potential, difficulty of control and broad polyphagy. The aim of this study was to measure, by means of the electroantennogram recordings, the antennal olfactory sensitivity of C. capitata in both sexes, in virgin and mated, lab-reared and wild flies following stimulation with fruit and leaf headspace of some host-plants: clementine, orange, prickly pear, lemon and apple. The results show that: a) lab-reared mated males are more sensitive to host plant fruit and leaf headspace than females, while the opposite was true for wild insects; b) antennae of wild virgin males were more sensitive than the mated ones, while no difference was observed among lab-reared medflies; c) lab-reared virgin females were more sensitive than mated ones, while few differences were found within wild medflies; d) in mated insects, lab-reared males were more sensitive to both host plant fruits and leaves than the wild ones, while the opposite was found for females. Taken together, these results show that the olfactory sensitivity to host plant odors differs between virgin and mated, and lab-reared and wild flies