Chemosensory Regulation of Feeding

Chapman, R. F.

doi:10.1007/978-1-4615-1775-7_4

Cited by 57 publications

(61 citation statements)

References 106 publications

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“…The first of these predictions is met by all organisms, from bacteria to mammals (for example, for insects, see Chapman, 1995). Regarding the second prediction, we have, within the context of the geometric framework, developed a mathematical model for the response properties of gustatory systems that would allow an animal to demonstrate several adaptive behavioural responses: (a) to mix its intake of two or more complementary foods to provide the optimal concentrations and balance of nutrients in its diet; (b) to eat predominantly from the optimal food, if it is available; (c) to ingest most of the food that is closest to being optimal if all available foods are suboptimal and noncomplementary in composition.…”

Section: Mechanistic Hypotheses: the Design Of Taste Systemsmentioning

confidence: 99%

Assuaging nutritional complexity: a geometrical approach

Simpson

Raubenheimer

1999

Proc. Nutr. Soc.

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We have introduced a framework that enables the identification of the important elements in complex nutritional systems, and the quantification of the interactions among them. These interactions include those among the multiple constituents of the ingesta, as well as between behavioural (ingestive) and physiological (post-ingestive) components of nutritional homeostasis. The resulting descriptions provide a powerful means to generate and test hypotheses concerning the mechanisms, ecology and evolution of nutritional systems. We provide an overview of the key concepts involved in our scheme, and then introduce four examples in which the framework is used to develop and test hypotheses. In the first example we use comparative methods based on a data set of 117 insect species to test a prediction about the relationship between evolving an association with bacterial endosymbionts and the composition of the optimal diet. Second, using two species of locusts (a grass specialist and a generalist), we consider the relationship between an animal's diet breadth and the decision rules employed when feeding on foods containing suboptimal protein : carbohydrate values. Third, we introduce a mathematical model that predicts the dose-response properties of gustatory systems in the context of nutritional homeostasis. Finally, we consider the interaction between tannic acid and macronutrient balance in the diet of locusts. Nutrient balancing: Geometric models of nutrition: Insects: Feeding behaviourNutritional regulation by an animal represents the integrated outcome of a highly complex set of interacting processes, operating over a range of scales of organization. Central to these processes is the acquisition and allocation of the more than thirty different nutrient molecules required for survival and reproduction. These nutrient molecules come packaged in various ratios and concentrations within foods, which may also contain an array of non-nutritive molecules, some of which are harmful. Foods are distributed across space and time, and finding, eating, digesting, assimilating and utilizing them involves ecological and physiological costs and compromises. Further, the nutritional environment is frequently highly variable, at a series of different scales; spatial variation occurs from mouthful-to-mouthful, patchto-patch and locality-to-locality, while temporal variation spans physiological, developmental and evolutionary time. Equally variable are the requirements of the animal, which are multidimensional and change quantitatively and qualitatively as an individual grows, develops, becomes reproductively active, then senesces.

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Section: Mechanistic Hypotheses: the Design Of Taste Systemsmentioning

confidence: 99%

Assuaging nutritional complexity: a geometrical approach

Simpson

Raubenheimer

1999

Proc. Nutr. Soc.

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“…In recent years, we have been analyzing the central pathways responsible for taste processing in the comparatively simple nervous system of the locust (Newland, 1999), in which the taste receptors, or basiconic sensilla, are distributed over most of the body surface (Chapman, 1982). At the sensory level, the consensus has been that across-fiber pattern coding is used (Chapman, 1995). We have been able to focus our analyses on readily accessible taste receptors that project to regions of the CNS that we know in detail (Burrows, 1996) and to which we have developed a model of chemosensory-elicited behavior .…”

Section: Abstract: Chemosensory Processing; Taste; Local Circuits; Smentioning

confidence: 99%

Gustatory Processing in Thoracic Local Circuits of Locusts

Rogers

Newland

2002

J. Neurosci.

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Recent reviews highlight a longstanding controversy about how different taste qualities are coded in the CNS. To address this issue, we have analyzed gustatory coding in the relatively simple and accessible nervous system of the locust, in which neural responses and gustatory elicited behavior are readily comparable. The intracellular responses of a population of spiking local interneurons in the metathoracic ganglion that receive monosynaptic inputs from chemosensory afferents were analyzed in response to stimulation with droplets of four behaviorally relevant chemicals: sodium chloride, sucrose, lysine glutamate, and nicotine hydrogen tartrate. There was a significant positive correlation between chemical concentration and response duration and the number of spikes evoked in 81% of interneurons sampled. The threshold of sensitivity to different chemicals varied but was consistent between all interneurons tested, being most sensitive to nicotine hydrogen tartrate and least sensitive to sucrose. Each interneuron responded similarly to specific chemicals at single concentrations. Interneurons that responded phasically to one chemical responded similarly to others, whereas interneurons that responded phasotonically to one stimulus also did so to others. Hindleg motor neurons also responded in a concentration-dependent manner to all test chemicals. Therefore, we found no interneurons or motor neurons that responded only to specific chemicals. We discuss the responses of the local circuit neurons in relation to the known chemically evoked behavioral responses of locusts and suggest that the aversiveness of a chemical, rather than its identity, is encoded directly in the local circuits.

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“…Other compounds, deterrents, inhibit feeding. This was the effect of KCl in Manduca (Hanson) and of azadirachtin in larval Pieris (van Loon & Schoonhoven) and it has long been clear that feeding (or the activation of the mandibular pattern generator) depends on a balance between phagostimulatory and deterrent inputs from the periphery (Chapman, 1995b;Schoonhoven et al, 1998).…”

Section: The Gustatory Systemmentioning

confidence: 99%

“…For many years, integration had been thought to occur only in the central nervous system so that a knowledge of the responses of the individual neurones in a sensillum to their particular stimulating chemicals would enable us to understand the chemosensory basis of food selection behaviour. Over the last 15 years, however, there have been increasing numbers of examples of interactions occurring at the periphery within each sensillum so that the responses of the individual neurones are not independent and the activity of any one cell is determined by the suite of chemicals reaching the dendrites of the whole ensemble (e.g., Dethier & Bowdan, 1989;Mitchell, 1988; brief reviews in Chapman, 1995b;Schoonhoven et al, 1998). Thus, it is now clear that integration occurs at the peripheral receptors as well as in the CNS and this is a common, if not a general, phenomenon when an insect encounters food.…”

Section: The Gustatory Systemmentioning

confidence: 99%

“…This implies the presence of receptors capable of distinguishing between different nutrients and several species are known to have separate neurones in mouthpart receptors that respond to sugars, amino acids and inorganic salts (Chapman, 1995b;Schoonhoven et al, 1998). Earlier work by Simpson and his associates has shown that the sensitivity of these cells varies with the nutrient content of the haemolymph.…”

Section: Possible Neural Basis Of Food Selectionmentioning

confidence: 99%

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