Seasonal variation in reversal learning reveals greater female cognitive flexibility in African striped mice

Learning and memory processes in behavioural addiction: A systematic review

Similar to addictive substances, addictive behaviours such as gambling and gaming are associated with maladaptive modulation of key brain areas and functional networks implicated in learning and memory. Therefore, this review sought to understand how different learning and memory processes relate to behavioural addictions and to unravel their underlying neural mechanisms. Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we systematically searched four databases - PsycINFO, PubMed, Scopus, and Web of Science using the agreed-upon search string. Findings suggest altered executive function-dependent learning processes and enhanced habit learning in behavioural addiction. Whereas the relationship between working memory and behavioural addiction is influenced by addiction type, working memory aspect, and task nature. Additionally, long-term memory is incoherent in individuals with addictive behaviours. Consistently, neurophysiological evidence indicates alterations in brain areas and networks implicated in learning and memory processes in behavioural addictions. Overall, the present review argues that, like substance use disorders, alteration in learning and memory processes may underlie the development and maintenance of behavioural addictions.

Risk-sensitive learning is a winning strategy for leading an urban invasion

In the unpredictable Anthropocene, a particularly pressing open question is how certain species invade urban environments. Sex-biased dispersal and learning arguably influence movement ecology, but their joint influence remains unexplored empirically, and might vary by space and time. We assayed reinforcement learning in wild-caught, temporarily captive core-, middle-, or edge-range great-tailed grackles-a bird species undergoing urban-tracking rapid range expansion, led by dispersing males. We show, across populations, both sexes initially perform similarly when learning stimulus-reward pairings, but, when reward contingencies reverse, male-versus female-grackles finish 'relearning' faster, making fewer choice-option switches. How do male grackles do this? Bayesian cognitive modelling revealed male grackles' choice behaviour is governed more strongly by the 'weight' of relative differences in recent foraging payoffs-i.e., they show more pronounced risk-sensitive learning. Confirming this mechanism, agent-based forward simulations of reinforcement learning-where we simulate 'birds' based on empirical estimates of our grackles' reinforcement learning-replicate our sex-difference behavioural data. Finally, evolutionary modelling revealed natural selection should favour risk-sensitive learning in hypothesised urban-like environments: stable but stochastic settings. Together, these results imply risk-sensitive learning is a winning strategy for urban-invasion leaders, underscoring the potential for life history and cognition to shape invasion success in human-modified environments.

Cognitive flexibility in urban yellow mongooses, Cynictis penicillata

Cognitive flexibility enables animals to alter their behaviour and respond appropriately to environmental changes. Such flexibility is important in urban settings where environmental changes occur rapidly and continually. We studied whether free-living, urban-dwelling yellow mongooses, Cynictis penicillata, in South Africa, are cognitively flexible in reversal learning and attention task experiments (n = 10). Reversal learning was conducted using two puzzle boxes that were distinct visually and spatially, each containing a preferred or non-preferred food type. Once mongooses learned which box contained the preferred food type, the food types were reversed. The mongooses successfully unlearned their previously learned response in favour of learning a new response, possibly through a win-stay, lose-shift strategy. Attention task experiments were conducted using one puzzle box surrounded by zero, one, two or three objects, introducing various levels of distraction while solving the task. The mongooses were distracted by two and three distractions but were able to solve the task despite the distractions by splitting their attention between the puzzle box task and remaining vigilant. However, those exposed to human residents more often were more vigilant. We provide the first evidence of cognitive flexibility in urban yellow mongooses, which enables them to modify their behaviour to urban environments.

Cognitive performance is linked to survival in free-living African striped mice

Cognition is shaped by evolution and is predicted to increase fitness. However, the link between cognition and fitness in free-living animals is unresolved. We studied the correlates of cognition and survival in a free-living rodent inhabiting an arid environment. We tested 143 striped mice (Rhabdomys pumilio) using a battery of cognitive tests, including: (i) an attention task, (ii) two problem-solving tasks, (iii) a learning and reversal learning task, and (iv) an inhibitory control task. We related cognitive performance with days of survival. Better problem-solving and inhibitory control performance were significant correlates of survival. Surviving males showed greater reversal learning which may be related to sex-specific behavioural and life-history characteristics. Specific cognitive traits and not a composite measure of general intelligence underpins fitness in this free-living rodent population, enhancing our understanding of the evolution of cognition in non-human animals.

The contribution of executive functions to sex differences in animal cognition

Cognitive sex differences have been reported in several vertebrate species, mostly in spatial abilities. Here, I review evidence of sex differences in a family of general cognitive functions that control behaviour and cognition, i.e., executive functions such as cognitive flexibility and inhibitory control. Most of this evidence derives from studies in teleost fish. However, analysis of literature from other fields (e.g., biomedicine, genetic, ecology) concerning mammals and birds reveals that more than 40% of species investigated exhibit sex differences in executive functions. Among species, the direction and magnitude of these sex differences vary greatly, even within the same family, suggesting sex-specific selection due to species' reproductive systems and reproductive roles of males and females. Evidence also suggests that sex differences in executive functions might provide males and females highly differentiated cognitive phenotypes. To understand the evolution of cognitive sex differences in vertebrates, future research should consider executive functions.

Variation in brain volume in nine populations and three taxa of the African striped mouse Rhabdomys

Brain size can vary between populations in different environments because of different selection pressures on behaviours, such as learning and memory, related to spatial, social and environmental differences. We investigated the variation in total and broad-scale regional brain size in the murid rodent genus Rhabdomys from different environments. We assessed taxon-, population- and sex-level differences in total and regional brain volume in three populations each of three taxa (arid-occurring R. pumilio and mesic-occurring R. dilectus chakae and R. d. dilectus) originating across southern Africa. We μCT-scanned crania obtained from museums in South Africa and used digital software to create endocasts and extract total endocranium and regional volumes: olfactory bulb, anterior cerebrum, posterior cerebrum, cerebellum volume, and petrosal volume. Total endocranial volume scaled with basal skull length and all region volumes scaled with total endocranial volume. We found taxon-, and population-level differences in total endocranial volume. Relative anterior and posterior cerebrum volume did not differ significantly between taxa or populations, but relative cerebellum volume was larger in arid populations than mesic populations. Relative olfactory bulb volume was larger in mesic R. dilectus than in the R. pumilio, but petrosal lobule volume was larger in R. pumilio populations than in R. dilectus. Males had larger total endocranial volumes than females. Drivers of larger total endocranial volumes in R. pumilio are not immediately clear from our results. Environmental seasonality of food availability, cognitive buffering and locomotion may all correlate with total endocranial volume size, whereas the influence of sociality cannot be excluded. The environment and degree of semi-arboreality are likely driving variation in cerebellum, olfactory bulb and petrosal lobule volumes. This article is protected by copyright. All rights reserved.