Scientists Investigate Correlation Between Personality and Cognitive Ability in Wild ZebraFish

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Samarpita Sen

Danio rerio (the zebrafish), a tropical fish from the minnow family often used as a popular model organism

  The correlation between cognition and personality in an individual is still a murky one, and holds the key to many important questions in evolutionary biology. This article briefly discusses some of the latest findings concerning this correlation by using the zebrafish as a model organism.



  A study led by a community ecologist group on wild Zebrafish (Danio rerio) at the Indian Institute of Science, Education and Research (IISER), Kolkata, has revealed that individual differences within the population of this tiny freshwater fish, in specific personality traits such as boldness and navigation capabilities, affects their learning potential and memory retention.

  Multiple studies have explored personality traits and cognitive behaviours like learning and problem-solving in zebrafish separately, but not much was known about the correlation between the two traits.

  Interestingly, studies which have comprehensively investigated the associations between the Big Five personality domains (Openness, Extraversion, Agreeableness, Emotional Stability and Conscientiousness) have been performed on humans before [1,2]. They point towards a positive link between cognitive ability and Openness and Emotional Stability and a negative association between cognitive ability and Conscientiousness.

  Though such correlations can be expected to occur in the most cognitively developed animals of all - humans and some other non-human mammals as well, reviewed in [5,6], studies exploring such associations in lower organisms are very few in number.

  “Our study investigates the underlying pattern, if any exists, between personality and cognitive ability and, if so, whether that relationship persists for all individuals within this zebrafish population. We also tested our fish in the presence and absence of a predator to examine how they were affected by the appearance of a threat and, if some fish were less affected than others, signifying an inherent difference in personality.”, said Anuradha Bhat, the principal investigator of this study, recently published in Frontiers in Behavioral Neuroscience[3].

  The zebrafish population exhibited clear effects of personality traits on learning and memory retention with bolder fish being quicker to explore and exhibiting better navigation skills in a spatial task. They also had better rates of learning and showed greater improvement in their performance at the end of the training as compared to their shy group members. Surprisingly memory retention was found to be poorer in bold fish which can be attributed to “their greater exploration tendencies and hence their less likelihood to remain in the same area for long periods of time and therefore lacking the need for improved memory” as pointed out by Danita K. Daniel, the lead author of the study from IISERK.

  Another interesting aspect of this study is the effect of sex on personality traits as well as learning and memory. While females were found to be bolder than males, they turned out to be less explorative. Males though were initially shy, showed a greater tendency to explore, thereby reflecting the different strategies of the sexes in their natural habitat, with the males being farther ranging and exhibiting higher memory retention and the females remaining in restricted locations and exhibiting less memory retention. However, these sex-dependent differences are largely dependent on ecological factors and more often than not happens to be habitat and context-specific.

  Inherent differences in personality caused bolder individuals to be less affected by predator presence and the females being comparatively bolder than males in different contexts seemed to attach less importance to the predator. They even go to the extent of performing far more predator inspections than their shy opposite gender.

  The study establishes that a correlation exists between personality traits and cognitive abilities like learning and memory, but Dr. Bhat points out that they are yet unsure about the “directionality” of this correlation. “It might be that fish that perform better at learning might be cognitively superior to the fish that perform poorly, and this allows them to take more risks, which results in them being bold. This could also lead to them being more adept at weighing the danger posed by a confined predator, and hence, they are less likely to show a difference in behaviour when under threat ”, says Dr. Bhat. The authors believe that bolder proactive individuals are likely to take more risks to explore novel environments which might lead to greater reproductive success than timid individuals that are unwilling to take risks and are generally shy. However, there are contradictory results in other fish species stating the reverse [4]. These studies propose that it is the shy or reactive individuals which show sensitivity to changes and hence perform better in a new environment, while bolder fish show routine formation and are unable to adapt rapidly.

  Svante Winberg, Professor of Behavioral Endocrinology at Uppsala University, Sweden, a scientist independent of this study, remarks that “It might be not just personality traits. There can be other factors like physiological and life history traits that may also be involved in the fish responses to changing environment thereby regulating their adaptability”. The authors are also of the opinion that further studies are absolutely necessary to dissect this complex interplay of personality and response to environmental changes.

  The scientists are still trying to uncover the underlying causes: Which parts of the brain specifically govern personality of an individual and why at all there is a correlation between personality and cognition in the first place.

  “This study just established the groundwork for understanding this relationship between personality and cognitive traits. It would be really interesting if we can observe whether this relationship persists across different populations of this species and also whether it is modified by the local environment. A lot of work still needs to be done in this respect”, Daniel concluded.

  We hope all these endeavours will collectively act as stepping stones to elucidate in detail the link between cognition and personality, that appears to be conserved across species in different animal systems, in spite of them being separated by millions of years of evolution.

  Aggravating this is the fact that unaffordable healthcare is a widely prevalent issue in many places; worries about this unaffordability manifesting itself in the coronavirus vaccine as well have been voiced by many.12

Bibliography

  1. Rammstedt et al, The association between personality and cognitive ability: Going beyond simple effects, Journal of Research in Personality 62 (2016) 39–44
  2. Rammstedt et al, Relationships between Personality and Cognitive Ability: A Facet-Level Analysis, J. Intell. 2018, 6, 28;
  3. Daniel et al, Bolder and Brighter? Exploring Correlations Between Personality and Cognitive Abilities Among Individuals Within a Population of Wild Zebrafish, Danio rerio, Frontiers in Behavioral Neuroscience, August 2020 | Volume 14 | Article 138
  4. Jolles, J. W. et al. (2019). Personality, plasticity and predictability in sticklebacks: bold fish are less plastic and more predictable than shy fish. Anim. Behav. 154, 193–202
  5. Thornton A, Lukas D, 2012. Individual variation in cognitive performance: developmental and evolutionary perspectives. Philos Trans Royal Soc Lond B Biol Sci 367:2773–2783.
  6. Lucon-Xiccato T, Bisazza A, 2017. Individual differences in cognition among teleost fishes. Behav Process 141:184–195

BS-MS Final Year Student, Department of Biological Sciences, IISER Kolkata. As a part of the lab "The Traffickers" , I study cellular copper import through a unique blend of experiments and simulation stuff.

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