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O papel da complexidade social durante o desenvolvimento no cérebro do peixe-zebra adulto
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Abstract(s)
Crescer em diferentes ambientes sociais durante o desenvolvimento influencia as habilidades cognitivas posteriores de um indivíduo, podendo também alterar a sua estrutura cerebral. De modo a explorar esta relação, foram escolhidos os peixes-zebra como modelo social – conhecidos por serem animais altamente sociais que estabelecem relações sociais estruturadas com os seus conspecíficos. Diferentes complexidades sociais – tamanho do grupo e estabilidade – que um indivíduo experiencia durante o desenvolvimento, foram estudadas. A estrutura cerebral de peixes adultos, particularmente a quantificação do número de neurónios e não-neurónios, foram analisados de modo a perceber se existe variações entre os diferentes grupos sociais, e de que forma é que estes números se distribuem nas diferentes regiões cerebrais. Observou-se que indivíduos que cresceram num grupo pequeno (com 6 elementos) estável (a viver sempre com os mesmos elementos) tiveram uma densidade neuronal global superior relativamente ao grupo grande (com 12 elementos) instável (a viver num grupo cujo os conspecíficos são substiuídos todas as semanas), ao grupo pequeno instável e ao grupo grande estável. A densidade neuronal na região do diencéfalo foi significativamente superior nos grupos estáveis, em comparação com os instáveis. Estes resultados sugerem que viver em grupos pequenos e estáveis pode ser cognitivamente mais desafiante e que o diencéfalo pode ter um papel crucial na regulação do comportamento social. Estes resultados constituem uma evidência de que o ambiente social que um indivíduo experiencia durante o desenvolvimento provoca diferenças na sua estrutura cerebral e indica que diferentes programas de desenvolvimento são adoptados em diferentes situações ambientais.
Living in different social environments throughout development lead to vastly distinct posterior cognitive abilities, and it may also change brain structure. To explore this relationship, zebrafishes, which are highly social animals that live in structured social relationships, were used as the social model in this thesis. Here, different social complexities – group size and stability – that individuals experience in early age were tested. Brain structures in adulthood, particularly the quantification of their neuronal and non-neuronal numbers, were checked to comprehend if there is a variation between treatments, and to understand how these numbers are spread throughout the several regions of the brain. Individuals who grew in a small (with 6 individuals) stable (living always with same conspecifics) group had a higher global density of neurons in comparison to the large (with 12 individuals) unstable (living in a group in which conspecifics change on a weekly basis) group, the small unstable and large stable group. The diencephalic neuronal density was also shown to be significantly higher in stable groups, in comparison with those individuals that grew in unstable groups. These main results suggest that living in small and stable groups could turn out to be cognitively challenging and the diencephalon might have a crucial importance in social behaviour regulation. Ultimately, this gives evidence to the fact that different social developmental environments play a relevant role in establishing differences in brain structure and indicate that different developmental programs are employed in different environment situations.
Living in different social environments throughout development lead to vastly distinct posterior cognitive abilities, and it may also change brain structure. To explore this relationship, zebrafishes, which are highly social animals that live in structured social relationships, were used as the social model in this thesis. Here, different social complexities – group size and stability – that individuals experience in early age were tested. Brain structures in adulthood, particularly the quantification of their neuronal and non-neuronal numbers, were checked to comprehend if there is a variation between treatments, and to understand how these numbers are spread throughout the several regions of the brain. Individuals who grew in a small (with 6 individuals) stable (living always with same conspecifics) group had a higher global density of neurons in comparison to the large (with 12 individuals) unstable (living in a group in which conspecifics change on a weekly basis) group, the small unstable and large stable group. The diencephalic neuronal density was also shown to be significantly higher in stable groups, in comparison with those individuals that grew in unstable groups. These main results suggest that living in small and stable groups could turn out to be cognitively challenging and the diencephalon might have a crucial importance in social behaviour regulation. Ultimately, this gives evidence to the fact that different social developmental environments play a relevant role in establishing differences in brain structure and indicate that different developmental programs are employed in different environment situations.
Description
Dissertação de Mestrado apresentada no ISPA – Instituto Universitário para obtenção de grau de Mestre na especialidade de Neurociências Cognitivas e Comportamentais
Keywords
Desenvolvimento Complexidade social Neurónios Diencéfalo Fraccionador isotrópico Development Social Complexity Neurons Diencephalon Isotropic Fractionator