Reward adaptation and the mechanisms of learning: contrast changes reward value in rats and drives learning

Formal theories of learning suggest that associations between events are determined by the internal representations of those events. Thus, learning should depend on perceived reward value—even when perceptions differ from objective values. We examined this prediction in flavor-preference learning in rats. In two experiments, simultaneous contrast either increased perceived reward value, which was paired with a distinctive flavor cue (the positive conditioned stimulus, CS+), or decreased the perceived value of the same reward, which was then paired with a second flavor (the negative conditioned stimulus, CS–). Even though the CS+ and CS– were paired with the same objective reward, there was a preference for the CS+ in subsequent tests. Moreover, the size of contrast-produced changes in reward value during training predicted the preference for the CS+ at test. This contrast-produced learning effect illustrates the mechanisms by which associations, which normally track veridical relationships between events in the world, are formed

Blocking of flavor-nausea learning by non-flavor cues: assessment through orofacial reactivity responses

We investigated, using orofacial reactivity assessment, whether nonflavor context cues can elicit conditioned aversive reactions, and also whether context cues interfere, through blocking, with the reduction in taste palatability during taste aversion conditioning. Experiment 1 showed that a context previously paired with LiCl evoked aversive orofacial reactions, and also attenuated the reduction in palatability of a saccharin solution which was paired with LiCl in that context. In Experiment 2, this blocking effect was abolished when the rats were given nonreinforced exposure to the previously LiCl-paired context (context extinction) before aversive conditioning of the saccharin in compound with the context. These results confirm that context stimuli can elicit conditioned aversive reactions in the absence of any flavor component, and demonstrate that context cues can interfere with the affective aspects of taste aversion learning. Thus nonflavor cues appear to engage the same processes as taste cues in aversion learning. These results are consistent with the idea that taste aversion learning is governed by general associative mechanisms and the special properties of nausea, rather than by a selective mechanism for poison-avoidance

As Concepções de Educação Física no Ocidente

A valorização do projecto educativo formal (intencional) sofreu no ocidente algumas transformações, notando-se muito cedo, e apesar da visão dualista sempre marcante, preocupações profundas com a formação integral do Homem. No entanto, o dualismo equilibrado Helénico teve condições históricas para se tornar em dualismo reducionista até à Idade Média, marcando significativamente, e no Renascimento, o início das abordagens científicas ao estudo da motricidade humana. O aprofundamento de áreas como a Educação Física (ginástica) e o Desporto moderno surgem, pois, num período conceptual em que de uma análise empírica e higiénico-terapêutica se vai passando a uma análise mais científica, inicialmente baseada na mecânica e na anatomia, e, à medida que se vão desenrolando os estudos médicos, na fisiologia geral e muscular. Este percurso emerge de uma episteme que gerava aquilo que hoje se costuma denominar como paradigma da modernidade e que, no âmbito da motricidade humana Manuel SÉRGIO (1989) denomina como paradigma cartesiano. A dicotomização corpo-espírito com desvalorização cultural do corpo e o desenvolvimento da ciência espartilhante face ao renascimento de uma visão limitada do conhecimento (conhecimento científico), envolvem movimentos recentes na sua contradição. É nesta transição de paradigma dominante que emerge o desenvolvimento da EF na escolaridade obrigatória

Conditioned hedonic responses elicited by contextual cues paired with nausea or with internal pain

Pairing a taste with either internal pain or nausea, despite equivalent effects on voluntary consumption, has dissociable effects on hedonic responses: Only pairing with nausea results in the production of disgust reactions, while pairing with internal pain results in conditioned fear as indicated by immobility. Here, we use orofacial reactions to examine the hedonic responses elicited by contextual, nonflavor, cues paired with nausea produced by injection of lithium chloride (LiCl) or internal pain caused by injection of hypertonic saline. In Experiment 1, aversive orofacial responses were the specific context-elicited behaviors in the rats injected with LiCl, whereas immobility was seen in the animals injected with hypertonic saline. In Experiment 2, rats first received discriminative training with two contexts, where one context was paired with LiCl or hypertonic saline, and the other context with isotonic saline. After this, rats were intraorally infused with a flavor (conditioned stimulus (CS) +) in the paired context, and with a different flavor (CS−) in the unpaired context. Second-order conditioning was then examined in a test conducted in the unpaired context. The infusion of the CS + flavor produced aversive orofacial responses in the rats injected with LiCl but immobility in the subjects injected with hypertonic saline. The results suggest that nonflavor cues support conditioned hedonic responses in the same way as flavor cues, which implies that the quality of aversion learning (conditioned nausea vs. fear) is primarily determined by the nature of the aversive event and not the type of conditioned cue

Functional brain networks underlying latent inhibition of conditioned disgust in rats

The present experiment examined the neuronal networks involved in the latent inhibition of conditioned disgust by measuring brain oxidative metabolism. Rats were given nonreinforced intraoral (IO) exposure to saccharin (exposed groups) or water (non-exposed groups) followed by a conditioning trial in which the animals received an infusion of saccharin paired (or unpaired) with LiCl. On testing, taste reactivity responses displayed by the rats during the infusion of the saccharin were examined. Behavioral data showed that preexposure to saccharin attenuated the development of LiCl-induced conditioned disgust reactions, indicating that the effects of taste aversion on hedonic taste reactivity had been reduced. With respect to cumulative oxidative metabolic activity across the whole study period, the parabrachial nucleus was the only single region examined which showed differential activity between groups which received saccharin-LiCl pairings with and without prior non-reinforced saccharin exposure, suggesting a key role in the effects of latent inhibition of taste aversion learning. In addition, many functional connections between brain regions were revealed through correlational analysis of metabolic activity, in particular an accumbens-amygdala interaction that may be involved in both positive and negative hedonic responses

“Ya nunca me verás como me vieras”. Algunas consideraciones sobre arte callejero

Este artículo propone una reflexión sobre diferentes formas de intervención urbana, a partir de una selección de registros fotográficos de graffitis, sténciles y arte callejero. La multiplicidad de expresiones que puede encontrarse en las paredes, con técnicas, estilos y objetivos muy variados, ofrece un campo interesante para analizar los mecanismos de producción y recepción de estas intervenciones y el lugar que ocupan en el paisaje urbano

Gloger’s rule in birds: adaptative meaning of melanine

[Resumen]: La regla de Gloger relaciona el grado de melanismo dentro de una especie con la latitud a la que ésta se encuentra, de forma que se esperaría encontrar un gradiente latitudinal en el cual los individuos más melánicos se situasen cerca del Ecuador y los menos melánicos en latitudes altas. Esta regla ha sido analizada en numerosas especies, pero en este TFG pretendo comprobar su aplicabilidad en un sentido más amplio comparando entre las especies de diferentes familias, así como discutir el posible significado adaptativo de la melanina con relación a los resultados obtenidos. Para ello analicé los patrones de melanismo de 13 familias de aves no paseriformes de amplia distribución geográfica, desarrollando un índice de melanismo cualitativo y estudiando el reparto de la melanina entre las diferentes partes del cuerpo. Los resultados revelan predominio de melanismo en latitudes mediterráneas, subtropicales y tropicales y ausencia de melanismo en latitudes altas, lo que nos lleva a sugerir que hay cierto patrón latitudinal del melanismo con la latitud, aunque no sea gradual. Se discuten varias posibles explicaciones del valor adaptativo de la pigmentación melánica en cabeza y alas, como un mayor refuerzo del extremo de las alas y una protección de la delicada cabeza frente a la radiación ultravioleta.[Resumo]: A regra de Gloger relaciona o grao de melanismo dentro dunha especie coa latitude á que se atopa, de forma que se esperaría atopar un gradiente latitudinal no cal os individuos máis melánicos estean situados preto do Ecuador, e os menos melánicos en latitudes altas. Esta regra foi analizada en numerosas especies, pero neste TFG pretendo comprobar a súa aplicabilidade nun sentido máis amplo, comparando entre as especies de diferentes familias, así como discutir o posible significado adaptativo da melanina con relación aos resultados obtidos. Para elo analicei os patróns de melanismo de 13 familias de aves non paseriformes de ampla distribución xeográfica, desenvolvendo un índice de melanismo cualitativo e estudando a repartición da melanina entre as diferentes partes do corpo. Os resultados revelan un predominio do melanismo en latitudes mediterráneas, subtropicais e tropicais e ausencia de melanismo coa latitude, aínda que non sexa gradual. Discútense varias posibles explicacións do valor adaptativo da pigmentación melánica en cabeza e ás, como un maior reforzo no extremo das ás e una protección da delicada cabeza fronte a radiación ultravioleta.[Abstract]: Gloger's rule links the degree of melanism within species to the latitude at which they occur. This rule has been analyzed within numerous species, but in this TFG I intend to test its applicability in a broader sense by comparing between species of different families, as well as to discuss the possible adaptive significance of melanin in relation to the results obtained. For this purpose, I analyzed the melanism patterns of 13 families of non-passerine birds of wide geographic distribution, developing a qualitative melanism index and studying the distribution of melanin among different body parts. The results reveal a predominance of melanism in Mediterranean, subtropical and tropical latitudes, and an absence of melanism at high latitudes, which leads us to suggest that there is some latitudinal pattern of melanism with latitude, although it is not gradual. Several possible explanations for the adaptive value of melanic pigmentation in the head and wings are discussed, such as increased wing tip reinforcement and protection of the delicate head from ultraviolet radiation.Traballo fin de grao (UDC.CIE). Bioloxía. Curso 2021/202

Fisheries catches and the carrying capacity of marine ecosystems in southern Brazil

The carrying capacity of marine shelf ecosystems in southern Brazil for harvestable species is analyzed by (1) quantifying the amount of available primary production appropriated by fisheries catches, (2) evaluating the trend in the mean trophic level of fisheries, and (3) simulating the ecosystem effects of “fishing down the food web” in an intensively exploited shelf region. Fisheries utilize ca. 27 and 53% of total primary production in the southern and south-eastern shelf regions, respectively. Regional variation in the carrying capacity appropriated by fisheries results from differences in the primary production, catch volume and trophic transfer efficiencies. Overall, fisheries landings do not display a trend of decreasing trophic level with time due to the collapse of the sardine fishery and the recent increasing of offshore fishing for higher trophic level species, mainly tunas and sharks. However, the simulations show that fishing down the food web through fisheries that target small pelagic planktivorous fishes, while at first increasing catches in intensively exploited regions, has the potential of decreasing yields, by interrupting major energy pathways to exploited, high-trophic level species. The consequences of these results to the design of precautionary measures for future fishing policies are discussed

La biblioteca de D. Andrés de Mondragón, I Marqués de Santa Cruz de Rivadulla, mecenas y político gallego del siglo XVIII (1645-1709)

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