| 1. |
- Abbey-Lee, Robin N., et al.
(author)
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The Influence of Rearing on Behavior, Brain Monoamines, and Gene Expression in Three-Spined Sticklebacks
- 2018
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In: Brain, behavior, and evolution. - Basel : S. Karger AG. - 0006-8977 .- 1421-9743. ; 91:4, s. 201-213
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Journal article (peer-reviewed)abstract
- The causes of individual variation in behavior are often not well understood, and potential underlying mechanisms include both intrinsic and extrinsic factors, such as early environmental, physiological, and genetic differences. In an exploratory laboratory study, we raised three-spined sticklebacks (Gasterosteus aculeatus) under 4 different environmental conditions (simulated predator environment, complex environment, variable social environment, and control). We investigated how these manipulations related to behavior, brain physiology, and gene expression later in life, with focus on brain dopamine and serotonin levels, turnover rates, and gene expression. The different rearing environments influenced behavior and gene expression, but did not alter monoamine levels or metabolites. Specifically, compared to control fish, fish exposed to a simulated predator environment tended to be less aggressive, more exploratory, and more neophobic; and fish raised in both complex and variable social environments tended to be less neophobic. Exposure to a simulated predator environment tended to lower expression of dopamine receptor DRD4A, a complex environment increased expression of dopamine receptor DRD1B, while a variable social environment tended to increase serotonin receptor 5-HTR2B and serotonin transporter SLC6A4A expression. Despite both behavior and gene expression varying with early environment, there was no evidence that gene expression mediated the relationship between early environment and behavior. Our results confirm that environmental conditions early in life can affect phenotypic variation. However, the mechanistic pathway of the monoaminergic systems translating early environmental variation into observed behavioral responses was not detected.
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| 2. |
- Sorato, Enrico, et al.
(author)
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Heritabilities and co-variation among cognitive traits in red junglefowl
- 2018
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In: Philosophical Transactions of the Royal Society of London. Biological Sciences. - London, United Kingdom : The Royal Society Publishing. - 0962-8436 .- 1471-2970. ; 373:1756
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Journal article (peer-reviewed)abstract
- Natural selection can act on between-individual variation in cognitive abilities, yet evolutionary responses depend on the presence of underlying genetic variation. It is, therefore, crucial to determine the relative extent of genetic versus environmental control of these among-individual differences in cognitive traits to understand their causes and evolutionary potential. We investigated heritability of associative learning performance and of a cognitive judgement bias (optimism), as well as their covariation, in a captive pedigree-bred population of red junglefowl (Gallus gallus, n > 300 chicks over 5 years). We analysed performance in discriminative and reversal learning (two facets of associative learning), and cognitive judgement bias, by conducting animal models to disentangle genetic from environmental contributions. We demonstrate moderate heritability for reversal learning, and weak to no heritability for optimism and discriminative learning, respectively. The two facets of associative learning were weakly negatively correlated, consistent with hypothesized trade-offs underpinning individual cognitive styles. Reversal, but not discriminative learning performance, was associated with judgement bias; less optimistic individuals reversed a previously learnt association faster. Together these results indicate that genetic and environmental contributions differ among traits. While modular models of cognitive abilities predict a lack of common genetic control for different cognitive traits, further investigation is required to fully ascertain the degree of covariation between a broader range of cognitive traits and the extent of any shared genetic control.
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| 3. |
- Zidar, Josefina, 1982-, et al.
(author)
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Environmental complexity buffers against stress-induced negative judgement bias in female chickens
- 2018
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In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8
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Journal article (peer-reviewed)abstract
- Cognitive processes are often biased by emotions. In humans, affective disorders are accompanied by pessimistic judgement, while optimistic judgement is linked to emotional stability. Similar to humans, animals tend to interpret ambiguous stimuli negatively after experiencing stressful events, although the long-lasting impact on judgement bias has rarely been investigated. We measure judgement bias in female chicks (Gallus gallus domesticus) after exposure to cold stress, and before and after exposure to additional unpredictable stressors. Additionally, we explore if brain monoamines can explain differences in judgement bias. Chicks exposed to cold stress did not differ in judgement bias compared to controls, but showed sensitivity to additional stressors by having higher motivation for social reinstatement. Environmental complexity reduced stress-induced negative judgement bias, by maintaining an optimistic bias in individuals housed in complex conditions even after stress exposure. Moreover, judgement bias was related to dopamine turnover rate in mesencephalon, with higher activity in individuals that had a more optimistic response. These results demonstrate that environmental complexity can buffer against negative effects of additive stress and that dopamine relates to judgement bias in chicks. These results reveal that both internal and external factors can mediate emotionally biased judgement in animals, thus showing similarities to findings in humans.
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| 4. |
- Zidar, Josefina, 1982-
(author)
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The relationship between personality and cognition in the fowl, Gallus gallus
- 2017
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Doctoral thesis (other academic/artistic)abstract
- To cope with a changing environment, animals have traditionally been considered to behave adaptively to each situation faced. Yet, individual behavioural responses can both differ widely within populations, and show between-individual consistency (i.e. describing variation in animal personality). In this thesis, I focus on individual differences in animal personality and cognition (i.e. how animals perceive, process, store and act on environmental stimuli), and explore the possibility that they are interlinked. I use domestic- and red junglefowl (Gallus gallus ssp.), a species that is cognitively, behaviourally and socially complex, to explore these aspects of behaviour, through a series of studies.Animal personality and coping styles are frequently used terms to describe within- and between-individual differences in behaviour, which are consistent over time and across various situations. The terms are often used as synonyms, even though they differ in some respects. In paper I, I show that animal personality and coping styles can be measured in red junglefowl, and that behavioural flexibility might be an important aspect for both. Further, I show that the terms should not be used as synonyms since they describe different aspects of behavioural variation.In paper II, I observe large individual variation in both personality traits and learning speed in both chicks and adult red junglefowl. Interestingly, learning performance does not correlate across tasks, contrasting what has been found in humans and rodents. Thus, individuals that learn rapidly in one task are not necessarily fast learners in another task. I observe a relationship between personality and cognition that is task- and age-dependent, in which exploration relates to learning speed, but in opposite directions for chicks compared to adult females. In paper III, I show that red junglefowl chicks that are more behaviourally flexible have a stronger preference for new generalised stimuli, than less behaviourally flexible chicks. Behavioural flexibility was associated with fearfulness, indicating variation in reactive-proactive coping styles. In paper IV, I show that early cognitive stimulation to some extent can affect adult personality, thus showing a causal relationship between personality and cognition. Not all personality traits were affected, which might depend on the type of cognitive stimulation chicks were exposed to.Important cognitive processes like perception and decision-making, can contain biases. One such bias is called judgment bias, which describes how individuals interpret ambiguous stimuli on a scale from positive to negative (optimism to pessimism). In paper V, I show that alteration of emotional state can influence such biases. Here, unpredictable stress influence judgment bias negatively, when individuals are housed in simpler, but not in complex environments, suggesting that there is an effect of additive stress that lead to reduced optimism. Complexity instead seems to buffer against negative effects of stress, since individuals in complex environments remained optimistic after stress exposure. Furthermore, increased dopamine activity was associated with optimism in chicks. In paper VI, I find that aspects of personality associate with how chicks judge ambiguity. Highly active individuals are more likely to approach cues than less active individuals, and when approaching, individuals that are slow to approach ambiguous cues are more vigilant when assayed in personality assays. Vigilant individuals might be more worried and reactive, which suggest that emotional traits can influence responses in a judgment bias task.Taken together, I show consistent behavioural differences among individuals describing personality and coping styles, and variation in cognition. I show that these traits are related, and that there is an interplay between them, in which cognition can influence personality, and vice versa. I further show that judgment may be affected by the individual’s current affective state and personality. Thus, I show a complex relationship between personality and cognition that in combination with environmental effects can help explain behavioural variation.
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