A esclerose multipla (EM) é uma doença neurodegenerativa autoimune. As células da glia contribuem para o agravamento da EAE. Este trabalho objetiva mostrar a influência da dexametasona, na progressão da doença e nos défcits cognitivos da EAE. Foram utilizados camundongos C57BL/6, fêmeas, divididos em 4 grupos (CONT, DEX, EAE, EAE+DEX) imunizadas com MOG e Bordetella Pertussis, tratados com dexametasona (50mg/kg). Antes e após o aparecimento dos sintomas, os animais foram submetidos a testes comportamentais de campo aberto, labirinto em cruz elevado, contexto aversivo e reconhecimento de objetos. Os animais tratados com dexametasona (EAE+DEX) apresentaram diminuição do escore clínico em relação ao grupo EAE e apresentaram comportamento do tipo ansioso. Entretanto, o tratamento com DEX promoveu diminuição da memória de trabalho. Houve aumento marcadores inflamatórios e aumento do número de astrócitos no hipocampo do grupo EAE+DEX no 26o dia. Estes dados sugerem que a dexametasona diminui a aquisição da memória e aumenta o número e reatividade astrocitária na EAE. / Multiple sclerosis (MS) is an autoimmune neurodegenerative disease. The glial cells contribute to the aggravation of EAE. This work aims to show an influence of dexamethasone, the progression of the disease and the cognitive deficits of EAE. Female C57BL/6 mice were divided into 4 groups (CONT, DEX, EAE, EAE+DEX) immunized with MOG and Bordetella Pertussis, treated with dexamethasone (50mg/kg). Before and after the onset of symptoms, the animals were submitted to behavioral tests open field, the elevated plus maze, the aversive context and the object recognition test. The animals treated with dexamethasone (EAE+DEX) presented a decrease in the clinical score in relation to the EAE group and presented an anxious type behavior. However, treatment with DEX promoted a decrease in the work memory. There were increased inflammatory markers and increased number of hippocampal astrocytes from the EAE+DEX group on the 26th day. These data suggest that dexamethasone decreases memory acquisition and increases the astrocytic number and reactivity in EAE.

Thesis (Ph. D.)--Ludwig-Maximilians-Universität München, 2006. / Title from PDF title page (viewed on June 4, 2006). Includes bibliographical references.

In North America, the grizzly bear (Ursus arcos) is one of many species increasingly threatened by the consequences of human-wildlife conflict, with human-bear encounters on the rise due to increased human activity near or in bear habitat. As a result, a growing number of bears are subjected to management measures such as translocations in which animals are moved to areas with lower risk of human conflict, although these measures are not always successful. Previous research has attempted to understand factors associated with translocation success, but new methods are needed to address the continuous and complex nature of issues related to how animals move and learn about their surroundings as well as how they adapt to novel environments. The objective of my MSc thesis is to develop and employ a novel agent-based computer simulation model to analyze how grizzly bears learn and respond following a translocation event. This modelling effort attempts to capture how bears make decisions based on multiple factors, and represent how grizzly bears interact with their environment and make movement decisions based on learned behaviours. First, an agent-based movement model was developed for female grizzly bears using GPS-location data for bears within a region in west-central Alberta, Canada. The model, which incorporates multi-scale decision-making and machine learning, generated movement patterns similar to those observed in radio-collared females in the study area. Home range sizes and movement metrics produced by the model were consistent with those observed in female grizzly bears in the area. The model was then used to simulate translocation events in which bears with varying “exploration” propensities were translocated to habitats with familiar or novel landscape characteristics. In general, bears translocated to habitats with similar landscape features to their original habitat were more likely to use high-quality habitat than bears moved to areas with very different landscape features. However, while increased exploration led to greater use of high-quality habitat in the long run, exploratory behaviour was found to be mostly detrimental during the first years following a translocation, the period considered critical for translocation success. Model results were found to be scale-dependent with results varying both in time and space, highlighting the need for a multi-scale approach to animal movement studies. The findings presented here also emphasize the need to account for behavioural traits of wildlife and habitat characteristics of the capture and release sites when selecting suitable translocation locations. This work highlights the potential for agent-based modelling as a tool to study animal movement as a continuous and complex process and evaluate conservation policies. / Graduate / 2021-08-24

Food-caching birds like black-capped chickadees offer unique advantages for studying neural processes underlying episodic memory. Chickadees exhibit prodigious memories—they can cache thousands of food items throughout their environment and use memory to navigate back to these hidden food stores. Additionally, their hippocampal circuit is simplified relative to that of mammals, containing far fewer inputs and outputs. However, little work had been done to understand the neural processes underlying these animal’s memory abilities. This thesis details several projects that aimed to better establish food-caching birds as an animal model of memory for systems neuroscience. In Chapter 2, we described the creation of behavioral tasks to utilize the chickadees’ natural memory behavior. Here, we monitored chickadees’ behavior while they cached food into a grid of sites covered by rubber flaps. We then applied probabilistic modeling to examine how different strategies guided birds’ choices during caching and retrieval. Chickadees used memories of the contents of individual cache sites in a context-dependent manner, avoiding sites that contained food during caching and returning to those same sites during retrieval. These results demonstrate memory flexibility in an animal in a tractable spatial paradigm. In Chapter 3, we asked whether the bird brain had a region that was similar to the entorhinal cortex. We found that the dorsal lateral hippocampal formation (DL/CDL), one of the main inputs to the chickadee hippocampus, sharded marked anatomical and physiological similarities to the mammalian entorhinal cortex. We first used retrograde and anterograde tracing to examine the connectivity between DL/CDL and the hippocampus, as well as DL and the rest of the pallium. We found that the topographic patterns of DL/CDL input were similar to those of the mammalian entorhinal cortex. We next examined the physiology of DL, using 1-photon calcium imaging to monitor neural activity while birds performed a random foraging task. Like the entorhinal cortex, DL contained multi-field ‘grid-like’ spatial neurons, as well as border cells, head direction cells and speed-tuned cells. Collectively, these results establish DL/CDL as an entorhinal cortex analog. In Chapter 4, we expanded the anatomical analysis to examine all of the inputs to the hippocampal formation. We varied our injections of retrograde tracers along the hippocampal long and transverse axes to examine if, like in mammals, there were topographic input patterns along these major axes. We found many patterns in input that were highly reminiscent of mammalian connectivity: like in rodents, visual pallial input preferentially innervated the septal portion of the hippocampus, while amygdala input preferentially targeted the temporal portion. These results further solidify the homology between the mammalian and avian hippocampal formations. Collectively, through these sets of experiments, we have laid the groundwork for studying the black-capped chickadee in a modern neuroscience context.

Working memory is the cognitive capacity for temporarily holding information in mind for processing or use, and supports most of our actions and behaviors. Although activity in the rodent prefrontal cortex (PFC) is necessary for successful rodent spatial working memory utilization, rodent spatial working memory tasks do not always evoke robust PFC delay encoding of retrospective spatial information. We hypothesized that, like in nonhuman primates (NHPs), increasing spatial optionality might facilitate the detection of retrospective spatial encoding in the PFC. We therefore used an automated 8-arm radial maze to implement a novel match-to-sample rodent spatial working memory task with seven options on each trial, and recorded calcium activity in PFC neurons during task performance. We found that, during the delay phase of the task, PFC neurons indeed encoded retrospective spatial representations of the arm visited in the preceding sample phase, at both single-cell and population levels, in a distributed manner. Also, in accordance with recent NHP work, these representations were evident in considering dynamic, heterogenous neural activity, and in considering a low-dimensional subspace, where time-invariant retrospective spatial information could be decoded. Thus, this work reveals that in rodents, freely-moving, spatially-demanding behavioral paradigms can evoke distributed spatial working memory representations in the prefrontal cortex, with reasonable similarity to the working memory representations observed in nonhuman primates.

A memória é considerada por muitos pesquisadores como um dos produtos mais fascinantes da evolução biológica, justamente por proporcionar aos animais a vantagem adaptativa de se utilizar de uma experiência prévia para a solução de problemas necessários para a sobrevivência. Os animais se utilizam de processos mnemônicos durante o forrageamento, a seleção de parceiros sexuais, seleção de habitat e a preferência alimentar. As aranhas são um modelo interessante em estudos de memória e há evidências do uso de experiências passadas na otimização do forrageio: a teia permite que as aranhas capturem e armazenem mais de um item alimentar. Há carência na literatura de estudos comparativos evolutivos da memória, o que dificulta identificar as possíveis pressões seletivas. O primeiro objetivo deste trabalho foi fazer um estudo comparativo de aspectos da memória predatória em aranhas do grupo Orbiculariae. Este grupo é monofilético e tem como principal sinapomorfia a construção de teia orbicular. Porém, ao longo da evolução, o padrão de teia foi se modificando desde uma estrutura plana até uma tridimensional. Tais modificações podem ter gerado diferenças comportamentais e no sistema de memória dessas aranhas. Por este motivo, o outro objetivo, foi traçar a evolução da memória dentro do grupo. Delinearam-se três grupos de estudo com sete espécies. Na condição natural, observou-se a captura de duas presas sucessivas. Na condição experimental I, ofereceu-se uma primeira presa (p1) à aranha e, em seguida, ofereceu-se uma segunda (p2); durante o deslocamento da aranha até p2, retirou-se p1 da teia. Na condição II, ao invés de se oferecer p2, a aranha foi atraída à periferia (simulando a queda de p2). No deslocamento da aranha até a fonte de vibração removeu-se p1. O indício de memória é observado quando, na supressão da presa, a aranha executa um comportamento denominado Busca. Neste, a aranha executa sacudidas/detecções dos fios no centro/refúgio da teia. A busca por p1 roubada foi observada em todas as espécies estudadas, exceto em Z. geniculata no grupo I. A presença de p2 parece interferir na expressão da memória de p1; deixar p2 na teia enquanto busca por p1, aumenta as chances de p2 também ser roubada por ação dos cleptoparasitas. Zosis apresenta algumas peculiaridades, entre elas a ausência de veneno. Dessa forma, o tempo gasto durante a imobilização de p2 parece ser suficiente para causar o esquecimento de p1. Todas as espécies buscaram por p1 quando não houve oferta de p2, inclusive Zosis. O tempo de busca, na condição I, diminui da base de Araneoidea até as famílias mais derivadas. No grupo II, há uma aparente inversão do sinal filogenético e o tempo de busca aumenta na família mais derivada. A estrutura da teia tridimensional parece ser mais complexa e, por este motivo, exigiria um sistema de navegação espacial também mais complexo quando comparado às aranhas orbitelas. A construção da teia parece ter sido crucial para a captura e armazenamento de presas excedentes, e tal comportamento, juntamente com a diversificação das teias, favoreceu a variação e evolução da memória na Ordem Araneae / Memory is one of the most fascinating products of biological evolution, because it endows animals with the adaptive use a prior experiences to solve survival problems. Animals use mnemonic processes during foraging, selection of sexual partners, habitat selection, and feeding preference. Spiders are an interesting model for studies of memory, and there is evidence of their using of past experiences in optimizing foraging: the web allows the spiders to capture and store more than one food item. In literature, there are few comparative studies, and no one about the evolution of memory, making it difficult to identify the possible selective pressures on memory. The first objective here was to make a comparative study on the aspects of predatory memory in spiders of the group Orbiculariae. This group is monophyletic and its main synapomorphy is building an orbicular web. However, during evolution, the web pattern changed from a flat to a three-dimensional structure. Such changes may have caused differences in behavior and memory. For that reason, another goal was to trace the evolution of memory within the group. We used three experimental groups with seven species each. In natural conditions, there was an observation of the capture of two successive preys. In the experimental condition I, a first prey (p1) was offered to the spider and, subsequently, another prey (p2) was offered; during the locomotion of the spider towards p2, p1 was removed from the web. In condition II, instead of offering p2, the spider was attracted to the periphery (simulating the fall of p2). As the spider moved towards the source of vibration, p1 was removed. The evidence of memory is observed when, in the suppression of the prey, the spider performs a behavior called search behavior: the spider runs plucking on threads in the web hub/retreat. The search for stolen p1 was observed in all species studied, except for Zosis geniculata in group I. The presence of p2 appears to interfere with the expression of p1 memory, and also leaving p2 on the web while searching for p1, increases the chances of having p2 stolen by the action of kleptoparasites. Zosis presents some peculiarities, including the absence of poison glands, leading to a prolonged immobilization of p2, in a time lag that could then be sufficient forget p1. All species sought by p1 when there was no offer of p2, including Zosis. The search time, in condition I, decreases from the base of Araneoidea until the most derived families. In group II, there is an apparent reversal of the phylogenetic signal and the search time increases in the most derived family. The three-dimensional structure of the derived webs seems to be more complex and, therefore, it would require a spatial navigation system also more complex if compared to the flat orbweb. The construction of the web seems to have been crucial for prey capture and storage of surpluses, and such behavior, along with the diversification of the webs, favored the variation and evolution of memory in the Order Araneae

The purpose of this study was to investigate the effects of cocaine on spatial memory consolidation using the Morris water maze. Specifically, male and female C57BL/6 mice were trained on a spatial water task, and then administered a single posttraining injection of saline or cocaine (1.25, 2.5, 5.0, or 20.0 mg/kg).

Abstract not available

A memória é considerada por muitos pesquisadores como um dos produtos mais fascinantes da evolução biológica, justamente por proporcionar aos animais a vantagem adaptativa de se utilizar de uma experiência prévia para a solução de problemas necessários para a sobrevivência. Os animais se utilizam de processos mnemônicos durante o forrageamento, a seleção de parceiros sexuais, seleção de habitat e a preferência alimentar. As aranhas são um modelo interessante em estudos de memória e há evidências do uso de experiências passadas na otimização do forrageio: a teia permite que as aranhas capturem e armazenem mais de um item alimentar. Há carência na literatura de estudos comparativos evolutivos da memória, o que dificulta identificar as possíveis pressões seletivas. O primeiro objetivo deste trabalho foi fazer um estudo comparativo de aspectos da memória predatória em aranhas do grupo Orbiculariae. Este grupo é monofilético e tem como principal sinapomorfia a construção de teia orbicular. Porém, ao longo da evolução, o padrão de teia foi se modificando desde uma estrutura plana até uma tridimensional. Tais modificações podem ter gerado diferenças comportamentais e no sistema de memória dessas aranhas. Por este motivo, o outro objetivo, foi traçar a evolução da memória dentro do grupo. Delinearam-se três grupos de estudo com sete espécies. Na condição natural, observou-se a captura de duas presas sucessivas. Na condição experimental I, ofereceu-se uma primeira presa (p1) à aranha e, em seguida, ofereceu-se uma segunda (p2); durante o deslocamento da aranha até p2, retirou-se p1 da teia. Na condição II, ao invés de se oferecer p2, a aranha foi atraída à periferia (simulando a queda de p2). No deslocamento da aranha até a fonte de vibração removeu-se p1. O indício de memória é observado quando, na supressão da presa, a aranha executa um comportamento denominado Busca. Neste, a aranha executa sacudidas/detecções dos fios no centro/refúgio da teia. A busca por p1 roubada foi observada em todas as espécies estudadas, exceto em Z. geniculata no grupo I. A presença de p2 parece interferir na expressão da memória de p1; deixar p2 na teia enquanto busca por p1, aumenta as chances de p2 também ser roubada por ação dos cleptoparasitas. Zosis apresenta algumas peculiaridades, entre elas a ausência de veneno. Dessa forma, o tempo gasto durante a imobilização de p2 parece ser suficiente para causar o esquecimento de p1. Todas as espécies buscaram por p1 quando não houve oferta de p2, inclusive Zosis. O tempo de busca, na condição I, diminui da base de Araneoidea até as famílias mais derivadas. No grupo II, há uma aparente inversão do sinal filogenético e o tempo de busca aumenta na família mais derivada. A estrutura da teia tridimensional parece ser mais complexa e, por este motivo, exigiria um sistema de navegação espacial também mais complexo quando comparado às aranhas orbitelas. A construção da teia parece ter sido crucial para a captura e armazenamento de presas excedentes, e tal comportamento, juntamente com a diversificação das teias, favoreceu a variação e evolução da memória na Ordem Araneae / Memory is one of the most fascinating products of biological evolution, because it endows animals with the adaptive use a prior experiences to solve survival problems. Animals use mnemonic processes during foraging, selection of sexual partners, habitat selection, and feeding preference. Spiders are an interesting model for studies of memory, and there is evidence of their using of past experiences in optimizing foraging: the web allows the spiders to capture and store more than one food item. In literature, there are few comparative studies, and no one about the evolution of memory, making it difficult to identify the possible selective pressures on memory. The first objective here was to make a comparative study on the aspects of predatory memory in spiders of the group Orbiculariae. This group is monophyletic and its main synapomorphy is building an orbicular web. However, during evolution, the web pattern changed from a flat to a three-dimensional structure. Such changes may have caused differences in behavior and memory. For that reason, another goal was to trace the evolution of memory within the group. We used three experimental groups with seven species each. In natural conditions, there was an observation of the capture of two successive preys. In the experimental condition I, a first prey (p1) was offered to the spider and, subsequently, another prey (p2) was offered; during the locomotion of the spider towards p2, p1 was removed from the web. In condition II, instead of offering p2, the spider was attracted to the periphery (simulating the fall of p2). As the spider moved towards the source of vibration, p1 was removed. The evidence of memory is observed when, in the suppression of the prey, the spider performs a behavior called search behavior: the spider runs plucking on threads in the web hub/retreat. The search for stolen p1 was observed in all species studied, except for Zosis geniculata in group I. The presence of p2 appears to interfere with the expression of p1 memory, and also leaving p2 on the web while searching for p1, increases the chances of having p2 stolen by the action of kleptoparasites. Zosis presents some peculiarities, including the absence of poison glands, leading to a prolonged immobilization of p2, in a time lag that could then be sufficient forget p1. All species sought by p1 when there was no offer of p2, including Zosis. The search time, in condition I, decreases from the base of Araneoidea until the most derived families. In group II, there is an apparent reversal of the phylogenetic signal and the search time increases in the most derived family. The three-dimensional structure of the derived webs seems to be more complex and, therefore, it would require a spatial navigation system also more complex if compared to the flat orbweb. The construction of the web seems to have been crucial for prey capture and storage of surpluses, and such behavior, along with the diversification of the webs, favored the variation and evolution of memory in the Order Araneae