Erika Roman

The ventral hippocampus (vHipp) is increasingly recognized for its role in processing probabilistic threats and emotional salience, yet the circuit mechanisms underlying these computations remain unclear. Here, we investigated how oriens-lacunosum moleculare interneurons expressing the α2 subunit of the nicotinic acetylcholine receptor (OLMα2 cells) contribute to hippocampal function along the longitudinal axis. Combining cell-type specific optogenetics, behavioral assays, monosynaptic and transsynaptic viral tracing, we compared intermediate hippocampal (iHipp) and vHipp OLMα2 populations. We show that OLMα2 cells exert regionally distinct control over behavior. Manipulation of iHipp OLMα2 cells selectively influenced object-directed exploration and novel object processing without affecting anxiety-like behavior, whereas vHipp OLMα2 cells modulated arousal and emotionally driven avoidance without contributing to object memory. Circuit tracing revealed that this functional double dissociation is paralleled by distinct connectivity profiles: iHipp is preferentially embedded in sensory cortical networks, whereas vHipp is strongly connected to limbic structures, including the basolateral amygdala and nucleus accumbens. Notably, despite robust regional amygdala-hippocampal connectivity, OLMα2 interneurons themselves received sparse direct amygdala input, indicating that emotional modulation is mediated indirectly via hippocampal pyramidal cell pathways. In contrast, stimulation of basolateral amygdala projections to vHipp promoted approach behavior without inducing generalized aversion, further supporting pathway- and cell-type specific encoding of valence and salience. Together, our findings demonstrate that OLMα2 interneurons implement a longitudinally organized inhibitory framework in which conserved microcircuit motifs yield distinct behavioral outcomes, depending on their embedding within region specific input and output networks. This work identifies a mechanistic basis for functional specialization along the hippocampal axis and highlights interneuron positioning as a key determinant of hippocampal contributions to cognition and emotion.

Lack of physical activity (PA) is a rising health challenge in both humans and companion dogs. Therefore, One Health strategies to increase PA in both species have been suggested. The aim of this pilot study was to evaluate the effects of a joint outdoor exercise program with jogging and circuit training sessions for dog-dog owner pairs (n = 15) on PA, sedentary time and sleep-related behaviors. Furthermore, the study aimed to assess fulfilment of global recommendations on PA in dog owners, and to compare accelerometer-derived and self-reported activity levels. Body measurements were used as secondary outcomes. Results showed an increase of vigorous-intensity PA by 5 min per day ( P = 0.04) and a reduction of sedentary time by 41 min in dog owners ( P = 0.01). Accelerometer data showed a high degree of fulfilment of recommendations for physical activity in dog owners at baseline. Self-reported PA and sedentary time were underestimated compared to accelerometer-derived data. No major changes in activity patterns in dogs were detected, but there was a slight but significant reduction of median body condition score. Sleep-related data indicated satisfactory nighttime sleep patterns in both species, with no considerable effects of the program. Both dog owners and dogs spent the main part of the daytime period sedentary. The exercise program may be useful for increasing vigorous PA and reducing sedentary time in dog owners. The high levels of PA in dog owners are in line with previous findings, and the underestimation of self-reported moderate-intensity PA suggests a strong integration of dog walking into daily routines. However, the high levels of sedentary time underline the importance of assessing sedentary behavior in addition to PA in both species in future studies. The findings should be confirmed in randomized controlled studies with larger sample size and long-term follow-up.

Introduction: Decision-making requires individuals to perceive probabilities and risks associated with different options. The Iowa gambling task (IGT) is a widely used instrument that assesses decision-making under uncertainty and risk by varying monetary reinforcer/loss contingencies. The rat gambling task (rGT), based on the IGT, is a preclinical test using varying number of palatable reinforcers as wins and different duration of timeouts as punishment, mimicking losses. The rGT requires extensive operant training prior to the free choice sessions. The aim of the present study was to investigate if task acquisition and number of training days affected subsequent individual differences in decision-making strategies in the rGT, and if behavioral profiles impacted on task learning.Method: Training time and performance of 70 male Lister Hooded rats from previously published studies were herein used to investigate whether learning time affected later decision-making strategies in the free choice rGT. Behavioral profiles generated from a subset of animals were used to study the impact of underlying behavior on learning time.Results: There were differences in training days between fast, intermediate and slow learners. However, time required to acquire the rGT did not affect subsequent decision-making strategies in the free choice rGT. Finally, learning time was independent of underlying behavioral profiles.Discussion: In conclusion, neither decision-making strategies in the rGT nor behavioral profiles were correlated or differed between animals with different learning speed. This suggests that the large variation in training time between animals is unrelated to subsequent decision-making strategies during free choice rGT. Such information is valuable for researchers using the rGT.

Background: The glycinergic system plays an important inhibitory role in the mouse central nervous system, where glycine controls the excitability of spinal itch- and pain-mediating neurons. Impairments of the glycine receptors can cause motor and sensory deficits. Glycine exerts inhibition through interaction with ligand-gated ion channels composed of alpha and beta subunits. We have investigated the mRNA expression of the glycine receptor alpha 3 (Glra3) subunit in the nervous system as well as in several peripheral organs of female and male mice. Results: Single-cell RNA sequencing (scRNA-seq) data analysis on the Zeisel et al. (2018) dataset indicated widespread but low expression of Glra3 in vesicular glutamate transporter 2 (Vglut2, Slc17a6) positive and vesicular inhibitory amino acid transporter (Viaat, Slc32a1)positive neurons of the mouse central nervous system. Highest occurrence of Glra3 expression was identified in the cortex, amygdala, and striatal regions, as well as in the hypothalamus, brainstem and spinal cord. Bulk quantitative real-time-PCR (qRT-PCR) analysis demonstrated Glra3 expression in cortex, amygdala, striatum, hypothalamus, thalamus, pituitary gland, hippocampus, cerebellum, brainstem, and spinal cord. Additionally, male mice expressed higher levels of Glra3 in all investigated brain areas compared with female mice. Lastly, RNAscope spatially validated Glra3 expression in the areas indicated by the single-cell and bulk analyses. Moreover, RNAscope analysis confirmed co-localization of Glra3 with Slc17a6 or Slc32a1 in the central nervous system areas suggested from the single-cell data. Conclusions: Glra3 expression is low but widespread in the mouse central nervous system. Clear sex-dependent differences have been identified, indicating higher levels of Glra3 in several telencephalic and diencephalic areas, as well as in cerebellum and brainstem, in male mice compared with female mice.

Edible insects are worldwide promoted as an alternative protein, trace mineral and lipid source in animal feed and human food. The house cricket (Acheta domesticus) is already being reared at an industrial scale, yet current mass-rearing practices and facility design may still leave room for improvement. Behavioral tests have been suggested as an important assessment tool at the whole-organism level that can be used to find optimal housing conditions (e.g. density, diet, temperature). Here, we adapt the widely used open field test to the house cricket. We tested 16 male and 16 female house crickets four times under two different light intensities. Videos were analysed with Ethovision^™ tracking software and variables distance moved, velocity, and duration and frequency in zone were extracted. Results showed that house crickets, like vertebrate model species, spent most time close to the walls of the arena, and crossed the center zone with high velocity. Brighter illumination was associated with increased velocity, in particular in the center zone during the first test occasion, suggesting avoidance of this zone. Male crickets had higher locomotory activity than females. Consistency repeatabilities and intraclass correlation coefficients (ICCs) were moderate to high, and the correlation between subsequent occasions became stronger over the four occasions at day 1, 2, 3 and 7. The first test occasion differed from subsequent occasions, therefore repeated testing may be necessary when analysing experimental manipulations of small effect size. Overall, the results are promising for use of the open field test as a precise phenotyping tool.

Introduction: Gambling disorder (GD) is the first non-substance or behavioral addiction to be included in substance-related and addictive disorders in DSM-5. Since GD is a younger phenomenon relative to alcohol and substance use disorders, little is known about potential unique features in GD and to what extent characteristics are shared with alcohol and substance use disorders. The rat gambling task (rGT) is used to study decision-making in rats. This study aimed to identify individual differences in rGT strategies and explore the stability of these strategies over time. Moreover, motor impulsivity, sexual behavior, and voluntary alcohol intake were examined in rats with different rGT strategies. Finally, the response to naltrexone on performance in rats with different rGT strategies was investigated.Methods: Male Lister hooded rats (n = 40) underwent repeated testing in the rGT, repeated copulatory behavioral tests, and 7 weeks of voluntary alcohol intake through a modified intermittent two-bottle free-choice paradigm. Finally, rats were treated with naltrexone prior to testing in the rGT.Results: The results revealed individual choice strategies in the rGT that were stable over time, even after multiple interruptions and other behavioral testing. The rats with a risky choice strategy displayed higher motor impulsivity and voluntary alcohol intake than the other groups. No difference in sexual behavior was found between the different rGT groups. Finally, in all rats irrespectively of rGT strategy, treatment with naltrexone decreased the number of completed trials and premature responses, and increased omissions, which indicates an overall lowered motivation.Discussion: In conclusion, rats with risky rGT strategies had higher voluntary alcohol intake but not elevated sexual behavior, indicating shared underlying mechanisms between rGT strategies and alcohol intake but not natural rewards in terms of sexual behavior. Finally, naltrexone treatment resulted in an overall lowered motivation in the rGT.

Decision-making requires that individuals perceive the probabilities and risks associated with different options. Experimental human and animal laboratory testing provide complimentary insights on the psychobiological underpinnings of decision-making. The Iowa gambling task (IGT) is a widely used instrument that assesses decision-making under uncertainty and risk. In the task participants are faced with a choice conflict between cards with varying monetary reinforcer/loss contingencies. The rat gambling task (rGT) is a pre-clinical version using palatable reinforcers as wins and timeouts mimicking losses. However, interspecies studies elaborating on human and rat behavior in these tasks are lacking. This study explores decision-making strategies among young adults (N = 270) performing a computerized version of the IGT, and adult outbred male Lister Hooded rats (N = 72) performing the rGT. Both group and individual data were explored by normative scoring approaches and subgroup formations based on individual choices were investigated. Overall results showed that most humans and rats learned to favor the advantageous choices, but to a widely different extent. Human performance was characterized by both exploration and learning as the task progressed, while rats showed relatively consistent pronounced preferences for the advantageous choices throughout the task. Nevertheless, humans and rats showed similar variability in individual choice preferences during end performance. Procedural differences impacting on the performance in both tasks and their potential to study different aspects of decision-making are discussed. This is a first attempt to increase the understanding of similarities and differences regarding decision-making processes in the IGT and rGT from an explorative perspective.

Individuals with gambling disorder display deficits in decision‐making in the Iowa Gambling Task. The rat Gambling Task (rGT) is a rodent analogue that can be used to investigate the neurobiological mechanisms underlying gambling behaviour. The aim of this explorative study was to examine individual strategies in the rGT and investigate possible behavioural and neural correlates associated with gambling strategies. Thirty‐two adult male Lister hooded rats underwent behavioural testing in the multivariate concentric square field™ (MCSF) and the novel cage tests, were trained on and performed the rGT and subsequently underwent resting‐state functional magnetic resonance imaging (R‐fMRI). In the rGT, stable gambling strategies were found with subgroups of rats that preferred the suboptimal safest choice as well as the disadvantageous choice, that is, the riskiest gambling strategy. R‐fMRI results revealed associations between gambling strategies and brain regions central for reward networks. Moreover, rats with risky gambling strategies differed from those with strategic and intermediate strategies in brain functional connectivity. No differences in behavioural profiles, as assessed with the MCSF and novel cage tests, were observed between the gambling strategy groups. In conclusion, stable individual differences in gambling strategies were found. Intrinsic functional connectivity using R‐fMRI provides novel evidence to support the notion that individual differences in gambling strategies are associated with functional connectivity in brain regions important for reward networks.