Biomedical subjects
Publications and source records attributed to D A Booth.
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A tactile pattern on the skin generally comes to be recognised from its function within action. What is perceived tactually and may generate a textural or geometrical sensation is therefore a set of dynamic characteristics that can be extracted by mechanoreceptors and central neural processing from the physics of the interactions of hands, mouth or other parts of the body with common objects and materials. The recognised dynamic (as is true of any sensory modality) may be diagnosable as distinct features that are integrated by the whole system's operation. If so, this transmission of feature information over a channel or in a dimension can be measured as the strength of the influence of that aspect of the stimulating pattern on the observed output, in units of the acuity of response differences for deviations of the pattern from its familiar configuration of features. When applied at the individual level, such multidimensional discrimination analysis provides powerful diagnoses of pattern-recognition processes.
The textural sensation generated by dairy creams and milks in the mouth was hypothesized to arise from mechanoreceptor stimulation by the viscosity of these oil-in-water emulsions and features arising from characteristics of the globules of fat. The viscosity, range of sizes of the fat globules and the average distance between globules were varied independently in dairy emulsions and samples rated for creaminess by six assessors. In this brief report, each assessor's performance is tested for multidimensional combinations of discriminations among viscosities, globule-size ranges and interglobule distances. Those individuals whose judgements of creaminess were sensitive to these physical variables appeared to differ greatly in the factors on which they based their judgements. This also depended on whether a high-fat milk or a light cream was used as the standard for comparison. Subject to confirmation of the stability of the discrimination space for an individual using a standard, it is preliminarily concluded that recognition of the physical properties of fat in dairy emulsions is highly idiosyncratic, perhaps indicating that it has to be learned.
Ten pairs of obese and nonobese monkeys, matched for age and sex, received one liquid test meal a day for 4 days. Testing was conducted during the middle of a 6-h period of food deprivation. At all other times the monkeys were freely fed on maintenance chow biscuits. The first test meal of grape and orange flavor drinks familiarized them with fluids containing an intermediate level of added carbohydrate (CHO) (27.5%); equal volumes of grape and orange flavors were presented. During testing, the positions of the two flavors were switched three times, thus forcing the monkey to make four choices during the meal. On days 2 and 3, four pairs of monkeys received low-energy liquid meals (10% CHO), and six pairs received high-energy meals (45% CHO); half of the pairs in each group had orange flavor, half grape. On day 2, meal volumes did not differ between the 10% and 45% CHO groups; rather, the size of the meal (regardless of CHO composition) correlated with mean daily chow intake. On day 3, the volume consumed of the 10% CHO solution increased and the volume of the 45% CHO solution decreased, generating a difference between groups that indicated one-trial learning of control of meal size. On day 4, each monkey was given a test meal of repeated choices between samples of grape and orange flavor, both containing the intermediate 27.5% CHO.(ABSTRACT TRUNCATED AT 250 WORDS)
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Questionnaire responses from a convenience sample were used to test for hypothesized relationships between changes over time in individuals' reported frequency of emotional eating and estimates of their success in attempts to reduce body weight over periods of at least 1 year. Respondents were 187 English adults, whose distribution of estimated Body Mass Indices (BMI) approximately that of the general population. Initial BMI was significantly (p less than 0.001) positively associated with reported frequency of emotional eating. Moreover, respondents indicating initially relatively high levels of emotional eating who reported a reduction in that level were found to lose significantly (p less than 0.01) more reported weight and to be significantly (p less than 0.05) more successful at approaching target weight over the period of the study than respondents who continued to report high levels of emotional eating. Similarly, respondents who reported an increase from initially relatively low levels of emotional eating, while not losing significantly less reported weight, were significantly (p less than 0.05) less successful at approaching target weight than those respondents who continued to report low levels of emotional eating.
Palatabilities and also satieties are assumption-loaded abstractions from the observable momentary causal relationships between eating or drinking and the situations in which it occurs. Palatability is neither in the food nor in the ingestive movements. Relative preference can vary with context, contrary to the usual concept of stable palatability. Satieties exemplify this, for they can be food-specific, i.e. ingestion-induced suppression of appetite may alter the supposed palatability hierarchy.
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The effects of dl-fenfluramine (2.5 mg/kg) on selection between the textures of nutrient preparations were tested by presenting rats with a choice between pairs of three sizes of chow crumb with 45% dextrin, casein, maltodextrin, or calcium caseinate added or with no nutrient added. The usual effect of fenfluramine was to reduce the intake preference for a coarser over a finer crumb. This drug effect differed, however, with the preparation of protein or of carbohydrate added to each crumb size. There was no consistent effect of nutrient, and hence the reported effects of this dose of dl-fenfluramine cannot be attributed to nutrient-specific selection.
Effects of the ingestion of protein and carbohydrate conditioned a preference for one size of chow particle over another, which was triggered by need for a specific nutrient. This learned elicitation of nutrient-specific dietary selection was not changed by injection of dl-fenfluramine HCl (2.5 mg/kg). This indicates that previously observed effects of fenfluramine on differential intakes of dextrin- and casein-rich diets do not depend on nutrient-specific self-selection.
Mildly food-deprived rats were presented at the same time either high- and low-carbohydrate diets or protein-containing and nonnutritive diets differing in flavor in parallel with nutrient composition. After a few days of these concurrent 10-minute presentations, the rats preferred the flavor of the richer or nutritive diet. Such preference conditioning also occurred when there was a 10-minute delay between the presentation of two flavors in nonnutritive diet and intubation of a mixture of nutrients in proportion to the flavor intakes. Thus, rats are able to perceive the difference between the nutritional aftereffects of two distinctive diets presented concurrently and to learn to respond differentially to associated flavors even when there was a delay as long as that used in earlier studies with pyloric closure. Therefore, the reinforcement that has been suggested to arise from gastric chemoreception can be attributed instead to delayed postgastric effects.