Publicação
Searching without information:a quantitative analysis of Caenorhabditis elegans locomotion
| Resumo: | Animal movement accounts for an important and highly complex process that affects many ecological systems at different temporal and spatial scales. When sources of food are not accessible in the surroundings, animals move through the environment to increase their chances of locating them and by adjusting the balance between local and non-local searches. Despite of being such an important ecological process, the behavioral mechanisms of search are still not well understood. The focus of this thesis is to disentangle the behavioral mechanisms responsible for individual locomotion of Caenorhabditis elegans, while searching in a bare, homogeneous experimental setting. Considering the nature of behavioral intermittency, we use sound statistical tests and methods to characterize the spatiotemporal search patterns. Our results show that, in the absence of environmental factors, C. elegans search behavior is influenced both by past experiences (informed behavior) and by a stochastic basal (non-informed) motor output. Informed movement, which is related with previous experiences and current memory state, originates at the beginning of the experiment, a local search behavior distinguished by an intensive exploration with high number of reorientations and short crawls. The non-informed motor output is characterized by a constant temporal and spatial pattern (over the whole experiment) of reorientations and long crawls. This behavior could be thought as of a locomotion template for the organism since it is neither controlled by external cues nor by specific internal state metabolisms. The existence of these two search modes suggest that the generated movement patterns are influenced by an interplay between internal and external motor outputs that is dependent on the information gathered from the environment. These findings contribute greatly for our understanding of the behavioral mechanisms responsible for the generation of complex movement patterns. |
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| Autores principais: | Salvador, Liliana M. |
| Assunto: | Caenorhabditis elegans Análise do movimento Locomoção animal Ecologia animal Teses de doutoramento - 2012 |
| Ano: | 2012 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Animal movement accounts for an important and highly complex process that affects many ecological systems at different temporal and spatial scales. When sources of food are not accessible in the surroundings, animals move through the environment to increase their chances of locating them and by adjusting the balance between local and non-local searches. Despite of being such an important ecological process, the behavioral mechanisms of search are still not well understood. The focus of this thesis is to disentangle the behavioral mechanisms responsible for individual locomotion of Caenorhabditis elegans, while searching in a bare, homogeneous experimental setting. Considering the nature of behavioral intermittency, we use sound statistical tests and methods to characterize the spatiotemporal search patterns. Our results show that, in the absence of environmental factors, C. elegans search behavior is influenced both by past experiences (informed behavior) and by a stochastic basal (non-informed) motor output. Informed movement, which is related with previous experiences and current memory state, originates at the beginning of the experiment, a local search behavior distinguished by an intensive exploration with high number of reorientations and short crawls. The non-informed motor output is characterized by a constant temporal and spatial pattern (over the whole experiment) of reorientations and long crawls. This behavior could be thought as of a locomotion template for the organism since it is neither controlled by external cues nor by specific internal state metabolisms. The existence of these two search modes suggest that the generated movement patterns are influenced by an interplay between internal and external motor outputs that is dependent on the information gathered from the environment. These findings contribute greatly for our understanding of the behavioral mechanisms responsible for the generation of complex movement patterns. |
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