Serotonin transporter (SERT) polymorphisms, personality and problem-solving in urban great tits

Understanding underlying genetic variation can elucidate how diversity in behavioral phenotypes evolves and is maintained. Genes in the serotonergic signaling pathway, including the serotonin transporter gene (SERT), are candidates for affecting animal personality, cognition and fitness. In a model species, the great tit (Parus major), we reevaluated previous findings suggesting relationships between SERT polymorphisms, neophobia, exploratory behavior and fitness parameters, and performed a first test of the relationship between single nucleotide polymorphisms (SNPs) in SERT and problem-solving in birds. We found some evidence for associations between SERT SNPs and neophobia, exploratory behavior and laying date. Furthermore, several SNPs were associated with behavioral patterns and success rates during obstacle removal problem-solving tests performed at nest boxes. In females, minor allele homozygotes (AA) for nonsynonymous SNP226 in exon 1 made fewer incorrect attempts and were more likely to problem-solve. In both sexes, there was some evidence that minor allele homozygotes (CC) for SNP84 in exon 9 were more likely to problem-solve. Only one SNP-behavior relationship was statistically significant after correcting for multiple comparisons, but several were associated with substantial effect sizes. Our study provides a foundation for future research on the genetic basis of behavioral and cognitive variation in wild animal populations.

A high-fat diet changes astrocytic metabolism to enhance synaptic plasticity and promote exploratory behavior

A high-fat diet (HFD) is generally considered to negatively influence the body, the brain, and cognitive abilities. On the other hand, fat and fatty acids are essential for nourishing and constructing brain tissue. Astrocytes are central for lipolysis and fatty acids metabolism. Here we show that exposure of young mice to one month of HFD elevates lipid content and increases the relative amount of reduced cytochromes in astrocytes but not in neurons. Metabolic changes were paralleled with an enlargement of astrocytic territorial domains due to an increased outgrowth of branches and leaflets. Astrocyte remodeling was associated with an increase in expression of ezrin and with no changes in glial fibrillary acidic protein (GFAP), glutamate transporter-1 (GLT-1), and glutamine synthetase (GS). Such physiological (non-reactive) enlargement of astrocytes in the brain active milieu promoted glutamate clearance and long-term potentiation. These changes translated into improved exploratory behavior. Thus, dietary fat intake is not invariably harmful and might exert beneficial effects depending on the biological context.

Zebrafish Model for Studying Dexamethasone-Induced Muscle Atrophy and Preventive Effect of Maca (Lepidium meyenii)

Loss of myofibers during muscle atrophy affects functional capacity and quality of life. Dexamethasone, an inducer of rapid atrophy of skeletal myofibers, has been studied as a glucocorticoid receptor in muscle atrophy or motor neurodegeneration. In this study, we examined dexamethasone-induced muscle atrophy using zebrafish (Danio rerio), a vertebrate model, and assessed whether administration of Lepidium meyenii (maca) as a dietary supplement can prevent muscle atrophy. Changes in skeletal myofibers in zebrafish were evaluated after exposure to dexamethasone for different periods and at different concentrations. Under optimized conditions, zebrafish pre-fed with maca for 3 days were exposed to 0.01% dexamethasone for 1 h/day for 7 days. Thereafter, myofiber loss, damaged muscle contractile proteins, and abnormal exploratory behavior due to the structural and functional impairment of skeletal muscle associated with muscle atrophy were investigated using hematoxylin–eosin, immunofluorescence staining, and behavioral analyses. Our findings suggest that dexamethasone induces muscle atrophy in zebrafish, inhibiting exploratory behavior by inducing myofiber loss, inhibiting muscle contraction, and causing changes in endurance and velocity. Thus, the zebrafish model can be used to screen pharmaceutical agents and to study muscle atrophy. Furthermore, maca is a potential dietary supplement to prevent muscle atrophy, as it protects muscle fibers.

Level Design Patterns That Invoke Curiosity-Driven Exploration

Video games frequently feature 'open world' environments, designed to motivate exploration. Level design patterns are implemented to invoke curiosity and to guide player behavior. However, evidence of the efficacy of such patterns has remained theoretical. This study presents an empirical study of how level design patterns impact curiosity-driven exploration in a 3D open-world video game. 254 participants played a game in an empirical study using a between-subjects factorial design, testing 4 variables: presence or absence of patterns, goal or open-ended, nature and alien aesthetic, and assured or unassured compensation. Data collection consisted of in-game metrics and emotion word prompts as well as post-game questionnaires. Results show that design patterns invoke heightened exploration, but this effect is influenced by the presence of an explicit goal or monetary compensation. There appear to be many motivations behind exploratory behavior in games, with patterns raising expectations in players. A disposition for curiosity (i.e. 'trait curiosity') was not found to influence exploration. We interpret and discuss the impact of the conditions, individual patterns, and player motivations.

Inhibitory hippocampo–septal projection controls locomotion and exploratory behavior

Although the hippocampus is generally considered a cognitive center for spatial representation, learning and memory, increasing evidence supports its roles in regulation of locomotion. However, the neuronal mechanisms of hippocampal regulation of locomotion and exploratory behavior remain unclear. Here we found that the inhibitory hippocampo-septal projection bi–directionally controls locomotion speed of mice. Pharmacogenetic activation of these septum–projecting interneurons decreased locomotion and exploratory behavior. Similarly, activation of the hippocampus–originated inhibitory terminal in the medial septum reduced locomotion. On the other hand, inhibition of the hippocampus–originated inhibitory terminal increased locomotion. The locomotion-regulative roles were specific to the septal projecting interneurons as activation of hippocampal interneurons projecting to the retrosplenial cortex did not change animal locomotion. Therefore, this study reveals a specific long-range inhibitory output from the hippocampus in the regulation of animal locomotion.

Application of Principal Component Analysis of Sows' Behavioral Indicators of the Welfare Quality® Protocol to Determine Main Components of Behavior

Understanding behavior is important in terms of welfare assessments to be able to evaluate possible changes in behavior among different husbandry systems. The present study applied principal component analysis (PCA) to reveal relationships between behavioral indicators to identify the main components of sows' behavior promoting feasibility of welfare assessments by providing possibilities for variable reduction and aggregation. The indicators of the Welfare Quality® protocol's principle to assess behavior were repeatedly applied by two observers on 13 farms in Northern Germany. This included Qualitative Behavior Assessments (QBA) to evaluate animals' body language using 20 pre-defined adjectives, assessments of social and exploratory behavior, stereotypies, and human–animal relationship tests. Two separate PCA were performed with respect to the QBA: (1) adjectives were included as independent variables and (2) adjectives were pre-aggregated using the calculation rules of the Welfare Quality® protocol for fattening pigs since a calculation for sows does not yet exist. In both analyses, two components described sows' behavior. Most variance was explained by the solution with adjectives as independent variables (51.0%). Other behavioral elements not captured as indicators by the protocol may still be important for all-inclusive welfare assessments as the required variance of 70% was not achieved in the analyses. Component loadings were used to determine components' labels as (1) “satisfaction of exploratory behavior” and (2) “social resting”. Both components reflected characteristics of sows' natural behavior and can subsequently be used for variable reduction but also for development of component scores for aggregation. As defined for PCA, component 1 explained more variance than component 2. PCA is useful to determine the main components of sows' behavior, which can be used to enhance feasibility of welfare assessments.