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Research Project
SOCIAL MODULATION OF ADULT NEUROGENESIS IN FISH
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Social interactions elicit rapid shifts in functional connectivity in the social decision-making network of zebrafish
Publication . Teles, Magda; Almeida, Olinda; Lopes, João Sollari; Oliveira, Rui Filipe
According to the social decision-making (SDM) network hypothesis, SDM is encoded in a network of forebrain and midbrain structures in a distributed and dynamic fashion, such that the expression of a given social behaviour is better reflected by the overall profile of activation across the different loci rather than by the activity of a single node. This proposal has the implicit assumption that SDM relies on integration across brain regions, rather than on regional specialization. Here we tested the occurrence of functional localization and of functional connectivity in the SDM network. For this purpose we used zebrafish to map different social behaviour states into patterns of neuronal activity, as indicated by the expression of the immediate early genes c-fos and egr-1, across the SDM network. The results did not support functional localization, as some loci had similar patterns of activity associated with different social behaviour states, and showed socially driven changes in functional connectivity. Thus, this study provides functional support to the SDM network hypothesis and suggests that the neural context in which a given node of the network is operating (i.e. the state of its interconnected areas) is central to its functional relevance.
Androgen response to social competition in a shoaling fish
Publication . Teles, Magda; Oliveira, Rui Filipe
Androgens respond to social challenges and this response has been interpreted as a way for males to adjust androgen-dependent behavior to social context. However, the androgen responsiveness to social challenges varies across species and a conceptual framework has been developed to explain this variation according to differences in the mating system and parental care type, which determines the regimen of challenges males are exposed to, and concomitantly the scope (defined as the difference between the physiological maximum and the baseline levels) of response to a social challenge. However, this framework has been focused on territorial species and no clear predictions have been made to gregarious species (e.g. shoaling fish), which although tolerating same-sex individuals may also exhibit intra-sexual competition. In this paper we extend the scope of this conceptual framework to shoaling fish by studying the endocrine response of zebrafish (Danio rerio) to social challenges. Male zebrafish exposed to real opponent agonistic interactions exhibited an increase in androgen levels (11-ketotestosterone both in Winners and Losers and testosterone in Losers). This response was absent in Mirror-fighters, that expressed similar levels of aggressive behavior to those of winners, suggesting that this response is not a mere reflex of heightened aggressive motivation. Cortisol levels were also measured and indicated an activation of the hypothalamic-pituitary-interrenal axis in Winners of real opponent fighters, but not Losers or in Mirror-fighters. These results confirm that gregarious species also exhibit an endocrine response to an acute social challenge.
Neurogenomic mechanisms of social plasticity
Publication . Cardoso, Sara D.; Teles, Magda; Oliveira, Rui Filipe
Group-living animals must adjust the expression of their social
behaviour to changes in their social environment and to transitions
between life-history stages, and this social plasticity can be seen as
an adaptive trait that can be under positive selection when changes
in the environment outpace the rate of genetic evolutionary change.
Here, we propose a conceptual framework for understanding the
neuromolecular mechanisms of social plasticity. According to this
framework, social plasticity is achieved by rewiring or by
biochemically switching nodes of a neural network underlying social
behaviour in response to perceived social information. Therefore, at
the molecular level, it depends on the social regulation of gene
expression, so that different genomic and epigenetic states of this
brain network correspond to different behavioural states, and the
switches between states are orchestrated by signalling pathways that
interface the social environment and the genotype. Different types of
social plasticity can be recognized based on the observed patterns
of inter- versus intra-individual occurrence, time scale and
reversibility. It is proposed that these different types of social plasticity
rely on different proximate mechanisms at the physiological, neural
and genomic level.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
PIDDAC
Funding Award Number
SFRH/BD/44848/2008