Pain and mere tastes
David Bain, Michael Brady, Jennifer Corns in Philosophy of Suffering, 2019
The most radical examples of rapid hedonic shifts are exhibited by what is known as conditioned taste aversion (CTA), or the Garcia effect (see, e.g., Garcia et al., 1974). CTA occurs when a distaste for a particular substance develops due to a single event that leads to the association of negative symptoms (primarily, nausea) with that substance. As the name attests, “conditioned taste aversion” is considered a (somewhat special – see below) example of classical conditioning or associative learning. More specifically, CTA is considered to be an instance of evaluative conditioning (EC), which is characterized by the psychological literature as the associative transfer of valence – i.e., as the process of acquiring likings/dislikings through associative learning or conditioning (see, e.g., De Houwer 2001, Rozin and Zellner 1985). EC occurs when changes in the valence of experiences of a stimulus result from pairing that stimulus with other “positive” or “negative” stimuli (i.e., stimuli that evoke experiences with positive or negative valence, respectively). Throughout multiple events (or laboratory trials), a neutral stimulus (e.g., a sound or a “neutral” taste) is paired with an affective stimulus (e.g., a “positive” taste), resulting in the transfer of the valence from experiences of the affective stimulus to experiences of the “neutral” (or differently valenced) stimulus. EC is canonically considered the standard process of acquiring tastes.24
The Central Connections of Area Postrema Define the Paraventricular System Involved in Antinoxious Behaviors
John Kucharczyk, David J. Stewart, Alan D. Miller in Nausea and Vomiting: Recent Research and Clinical Advances, 2017
Not all animals vomit. In animals incapable of vomiting, equivalent protection against the ingestion of noxious substances is achieved by conditioned taste aversion and by signaling distaste to conspecifics. Ingestion of unpalatable food evokes gaping, chin rubbing, head shaking, paw wiping, forelimb flailing,67 inactivity, salivation, and gagging, signals that are presumably utilized by conspecifics as warning signs. When accompanied by such signs of distaste, conditioned taste aversion may serve as an animal model of nausea,62 although caution is indicated in equating the two.68 When unconditioned stimuli such as lithium chloride (causing upper GI discomfort) are used to condition taste aversion, the conditioned stimuli acquire the capacity to evoke signs of distaste.69 In other words, appropriate stimuli paired with nausea become nauseating themselves, and this may mediate the aversion that prevents their ingestion.
Viscerogustatory Integration and Sensory Coding in the NTS
I. Robin A. Barraco in Nucleus of the Solitary Tract, 2019
The spatial and temporal aspects of the gustatory code signal stimulus quality according to a dimension of physiological welfare. In addition, NTS cells are sensitive to the internal state of the organism. The experience of a conditioned taste aversion or preference, the depletion of sodium reserves, and the exogenous administration of nutrients, all influence gustatory responsiveness, shifting the neural code to address the new condition. A formerly appetitive tastant, paired with nausea, generates a neural profile more akin to that of quinine and is subsequently avoided by the animal. A salt-deficient rat signals sodium through taste cells that are associated with positive hedonics, and the rat consumes sodium avidly. Exogenous administration of glucose, insulin, or glucagon suppresses responsiveness in neurons that signal positive hedonics and feeding is reduced. The sensitivity of taste to both the external and internal milieus, and the distribution of its signal to neural areas that impose the appropriate hedonic tone, guarantee the animal’s attraction to nutrients and its revulsion by toxins.
Effects of caloric or non-caloric sweetener long-term consumption on taste preferences and new aversive learning
Published in Nutritional Neuroscience, 2020
Gabriela Vera-Rivera, María-Isabel Miranda, José Alejandro Rangel-Hernández, Dennys Badillo-Juárez, Daniela Fregoso-Urrutia, Seraid Caynas-Rojas
Recent evidence in rodents indicates that consumption of artificial sweeteners, in which sweet taste is dissociated from normal caloric consequences, could induce changes in energy and body weight regulation.3 The disruption of energy regulation by sweeteners suggests that flavors, including all the orosensory cues, not only modify intake and appetitive behavior but also change learned and conditioned responses.4 Flavor-conditioned responses prepare the gastrointestinal tract for the arrival of nutrients and mediate the anticipation of food reward; specifically, a Pavlovian conditioning occurs when taste (e.g. sweet, bitter) becomes a conditioned stimulus (CS) for post-ingestive (e.g. nutritive, gastric malaise) unconditioned stimulus (US). As a result, taste CS evoke conditioned responses. An appetitive response may develop if the taste is nutritive and palatable, increasing taste consumption,5 or an aversion to a certain taste is acquired when its consumption is followed by gastric malaise, i.e. conditioned taste aversion (CTA).6
Effects of low-dose alcohol exposure in adolescence on subsequent alcohol drinking in adulthood in a rat model of depression
Published in The World Journal of Biological Psychiatry, 2021
Filip Siska, Petra Amchova, Daniela Kuruczova, Yousef Tizabi, Jana Ruda-Kucerova
The second hypothesis involves the amplification of the aversive properties of ethanol (Thibodeau and Pickering 2019),where consumption of low levels of unflavoured ethanol during adolescence could lead to augmentation of the aversive properties of ethanol in adulthood. This hypothesis, however, is less probable since adolescence is characterised by attenuated sensitivity to aversive stimuli (Anderson et al. 2010; Doremus-Fitzwater and Spear 2016). As evident, several studies indicated that pre-exposure to EtOH in both early and late adolescence can lead to long-term attenuation of conditioned taste aversion or conditioned place aversion caused by EtOH (Pautassi et al. 2015; Saalfield and Spear 2015; Williams et al. 2018). Nonetheless, some studies which focussed on ethanol-induced conditioned taste aversion did indeed show the possibility of aversion development in adolescent rodents (Anderson et al. 2010; Acevedo et al. 2013). Yet, these studies used significantly higher doses of EtOH to reach conditioned taste aversion and different models of EtOH exposure over the time compared to the current study. On this note, we also took into consideration the possibility of confounding factors increasing aversive properties of EtOH. However, maximum standardisation and constant environmental conditions were assured during the whole experiment. Therefore, there is only a small probability of stress caused by these conditions, which may possibly have a character of chronic mild stress proven to increase EtOH consumption (Marco et al. 2017; Vázquez-León et al. 2017).
Dietary macronutrient composition affects hypothalamic appetite regulation in chicks
Published in Nutritional Neuroscience, 2018
Betty R. McConn, Justin Matias, Guoqing Wang, Mark A. Cline, Elizabeth R. Gilbert
Dietary macronutrient composition plays an important role in regulating appetite and may affect the above-described pathways. In general, in mammals, relatively high-protein diets induce satiety7 and low-protein diets may induce an increase in food intake.8,9 The reduction in food intake that occurs with high-protein diets may be due to palatability, conditioned taste aversion, or induction of satiety, and is affected by the composition of the previous diet, including the concentration of protein and the protein to energy ratio.7 When rats were switched to a high-protein (14–50% total milk protein) diet there was an immediate (minutes) decrease in food intake followed by an increase but not complete recovery during a two-week feeding period.7 Behavioral analyses suggested that the reduction in intake (18% lower energy intake) following adaptation to the high-protein diet was indicative of satiety rather than malaise or conditioned taste aversion. The molecular mechanisms underlying these changes are unknown, although it is hypothesized that signals acting on the brain may originate from the gut during absorption or metabolically post-absorptively.7 Rats fed a low-protein diet (10% casein) ate about 25% more than control-fed animals after one day.9 It was hypothesized that a reduction in blood nitrogen from consuming the low-protein diet was associated with a reduction in available amino acids for neurotransmitter synthesis. Thus, amino acid metabolism likely plays an important role in appetite regulation and will be influenced by the amount of dietary protein and energy.
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