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Keywords = food reward/reinforcement

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14 pages, 259 KiB  
Review
Importance of Nutrition Care During the Addiction Recovery Process
by Alfonso Balmori and María Paz de la Puente
Psychoactives 2025, 4(3), 19; https://doi.org/10.3390/psychoactives4030019 - 20 Jun 2025
Viewed by 511
Abstract
Food can help release and promote neurotransmitters. As a result, the food’s effect in this regard is of great interest to individuals who have experienced dysregulation of the brain reward circuit due to addiction to drugs or other substances. This is one of [...] Read more.
Food can help release and promote neurotransmitters. As a result, the food’s effect in this regard is of great interest to individuals who have experienced dysregulation of the brain reward circuit due to addiction to drugs or other substances. This is one of the chief reasons why dietary choices can influence the success of drug addiction programs. While the general importance of nutrition was known previously—although it has been applied on few occasions—this review provides new knowledge that has emerged in recent years, which reinforces earlier findings regarding food’s importance in overcoming addiction. In the last 15 years, there has been great progress in the understanding of the human intestinal microbiota, its importance for health, and its connections with the brain. However, since this area of nutrition is such a new field of study, it has rarely been applied to or considered in treatment programs. At the same time, it is important to avoid a diet based on ultra-processed foods, which deteriorate the microbiome and consequently harm the restoration of the natural reward system. Although ongoing research will undoubtedly provide a wealth of information in the coming years, the knowledge currently available is enough to confirm the importance of diet in a person’s addiction recovery process. For this reason, it is important for patients and programs to follow a diet that regulates the brain’s natural neurotransmitters through the microbiota and restores the natural functioning of the reward circuit, helping to overcome cravings. Full article
21 pages, 1911 KiB  
Article
Optimizing Water Use in Maize Irrigation with Reinforcement Learning
by Muhammad Alkaff, Abdullah Basuhail and Yuslena Sari
Mathematics 2025, 13(4), 595; https://doi.org/10.3390/math13040595 - 11 Feb 2025
Cited by 1 | Viewed by 1614
Abstract
As global populations grow and environmental constraints intensify, improving agricultural water management is essential for sustainable food production. Traditional irrigation methods often lack adaptability, leading to inefficient water use. Reinforcement learning (RL) offers a promising solution for developing dynamic irrigation strategies that balance [...] Read more.
As global populations grow and environmental constraints intensify, improving agricultural water management is essential for sustainable food production. Traditional irrigation methods often lack adaptability, leading to inefficient water use. Reinforcement learning (RL) offers a promising solution for developing dynamic irrigation strategies that balance productivity and resource conservation. However, agricultural RL tasks are characterized by sparse actions—irrigation only when necessary—and delayed rewards realized at the end of the growing season. This study integrates RL with AquaCrop-OSPy simulations in the Gymnasium framework to develop adaptive irrigation policies for maize. We introduce a reward mechanism that penalizes incremental water usage while rewarding end-of-season yields, encouraging resource-efficient decisions. Using the Proximal Policy Optimization (PPO) algorithm, our RL-driven approach outperforms fixed-threshold irrigation strategies, reducing water use by 29% and increasing profitability by 9%. It achieves a water use efficiency of 76.76 kg/ha/mm, a 40% improvement over optimized soil moisture threshold methods. These findings highlight RL’s potential to address the challenges of sparse actions and delayed rewards in agricultural management, delivering significant environmental and economic benefits. Full article
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19 pages, 320 KiB  
Review
Food Addiction
by Haley Krupa, Ashley N. Gearhardt, Anne Lewandowski and Nicole M. Avena
Brain Sci. 2024, 14(10), 952; https://doi.org/10.3390/brainsci14100952 - 24 Sep 2024
Cited by 6 | Viewed by 4989
Abstract
In this review, we aim to draw a connection between drug addiction and overconsumption of highly palatable food (OHPF) by discussing common behaviors and neurochemical pathways shared by these two states. OHPF can stimulate reward pathways in the brain that parallel those triggered [...] Read more.
In this review, we aim to draw a connection between drug addiction and overconsumption of highly palatable food (OHPF) by discussing common behaviors and neurochemical pathways shared by these two states. OHPF can stimulate reward pathways in the brain that parallel those triggered by drug use, increasing the risk of dependency. Behavioral similarities between food and drug addiction can be addressed by tracking their stages: loss of control when eating (bingeing), withdrawal, craving, sensitization, and cross-sensitization. The brain adapts to addiction by way of the mesolimbic dopamine system, endogenous opioids and receptors, acetylcholine and dopamine balance, and adaptations of serotonin in neuroanatomy. Studies from the current literature are reviewed to determine how various neurological chemicals contribute to the reinforcement of drug addiction and OHPF. Finally, protocols for treating food addiction are discussed, including both clinical and pharmacological modalities. There is consistent evidence that OHPF changes brain chemistry and leads to addiction in similar ways to drugs. However, more long-term research is needed on food addiction, binge eating, and their neurobiological effects. Full article
19 pages, 3094 KiB  
Article
Diet-Induced Obesity Induces Transcriptomic Changes in Neuroimmunometabolic-Related Genes in the Striatum and Olfactory Bulb
by Rosario B. Jaime-Lara, Claudia Colina-Prisco, Marcel De Jesus Vega, Sarah Williams, Ted Usdin, Bridget Matikainen-Ankney, Alayna Kinkead, Brianna Brooks, Yupeng Wang, Alexis T. Franks, Alexxai Kravitz and Paule V. Joseph
Int. J. Mol. Sci. 2024, 25(17), 9330; https://doi.org/10.3390/ijms25179330 - 28 Aug 2024
Cited by 1 | Viewed by 1635
Abstract
The incidence of obesity has markedly increased globally over the last several decades and is believed to be associated with the easier availability of energy-dense foods, including high-fat foods. The reinforcing hedonic properties of high-fat foods, including olfactory cues, activate reward centers in [...] Read more.
The incidence of obesity has markedly increased globally over the last several decades and is believed to be associated with the easier availability of energy-dense foods, including high-fat foods. The reinforcing hedonic properties of high-fat foods, including olfactory cues, activate reward centers in the brain, motivating eating behavior. Thus, there is a growing interest in the understanding of the genetic changes that occur in the brain that are associated with obesity and eating behavior. This growing interest has paralleled advances in genomic methods that enable transcriptomic-wide analyses. Here, we examined the transcriptomic-level differences in the olfactory bulb and striatum, regions of the brain associated with olfaction and hedonic food-seeking, respectively, in high-fat-diet (HFD)-fed obese mice. To isolate the dietary effects from obesity, we also examined transcriptomic changes in normal-chow-fed and limited-HFD-fed groups, with the latter being pair-fed with an HFD isocaloric to the consumption of the normal-chow-fed mice. Using RNA sequencing, we identified 274 differentially expressed genes (DEGs) in the striatum and 11 in the olfactory bulb of ad libitum HFD-fed mice compared to the chow-fed group, and thirty-eight DEGs in the striatum between the ad libitum HFD and limited-HFD-fed groups. The DEGs in both tissues were associated with inflammation and immune-related pathways, including oxidative stress and immune function, and with mitochondrial dysfunction and reward pathways in the striatum. These results shed light on potential obesity-associated genes in these regions of the brain. Full article
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18 pages, 371 KiB  
Review
Ultra-Processed Foods and Mental Health: Where Do Eating Disorders Fit into the Puzzle?
by David A. Wiss and Erica M. LaFata
Nutrients 2024, 16(12), 1955; https://doi.org/10.3390/nu16121955 - 19 Jun 2024
Cited by 9 | Viewed by 11373
Abstract
Ultra-processed foods (UPFs) like pastries, packaged snacks, fast foods, and sweetened beverages have become dominant in the modern food supply and are strongly associated with numerous public health concerns. While the physical health consequences of UPF intake have been well documented (e.g., increased [...] Read more.
Ultra-processed foods (UPFs) like pastries, packaged snacks, fast foods, and sweetened beverages have become dominant in the modern food supply and are strongly associated with numerous public health concerns. While the physical health consequences of UPF intake have been well documented (e.g., increased risks of cardiometabolic conditions), less empirical discussion has emphasized the mental health consequences of chronic UPF consumption. Notably, the unique characteristics of UPFs (e.g., artificially high levels of reinforcing ingredients) influence biological processes (e.g., dopamine signaling) in a manner that may contribute to poorer psychological functioning for some individuals. Importantly, gold-standard behavioral lifestyle interventions and treatments specifically for disordered eating do not acknowledge the direct role that UPFs may play in sensitizing reward-related neural functioning, disrupting metabolic responses, and motivating subsequent UPF cravings and intake. The lack of consideration for the influences of UPFs on mental health is particularly problematic given the growing scientific support for the addictive properties of these foods and the utility of ultra-processed food addiction (UPFA) as a novel clinical phenotype endorsed by 14–20% of individuals across international samples. The overarching aim of the present review is to summarize the science of how UPFs may affect mental health, emphasizing contributing biological mechanisms. Specifically, the authors will (1) describe how corporate-sponsored research and financial agendas have contributed to contention and debate about the role of UPFs in health; (2) define UPFs and their nutritional characteristics; (3) review observed associations between UPF intake and mental health conditions, especially with depression; (4) outline the evidence for UPFA; and (5) describe nuanced treatment considerations for comorbid UPFA and eating disorders. Full article
(This article belongs to the Special Issue Nutritional Intervention in Mental Health)
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13 pages, 2858 KiB  
Article
Deciphering the Role of the Nucleus Accumbens Shell Area on Spatial Memory Deficits Induced by Neuropathic Pain in Rats
by Mariana Cerqueira-Nunes, Clara Monteiro, Vasco Galhardo and Helder Cardoso-Cruz
Appl. Biosci. 2024, 3(2), 283-295; https://doi.org/10.3390/applbiosci3020019 - 12 Jun 2024
Cited by 1 | Viewed by 1773
Abstract
The nucleus accumbens shell (NAcSh) is a major structure associated with distinct aspects of reward and mnemonic information encoding, relying on spatial data to define optimal behavioral strategies. Chronic pain-derived striatal plasticity is considered one underpinning cause of working memory (WM) impairments. However, [...] Read more.
The nucleus accumbens shell (NAcSh) is a major structure associated with distinct aspects of reward and mnemonic information encoding, relying on spatial data to define optimal behavioral strategies. Chronic pain-derived striatal plasticity is considered one underpinning cause of working memory (WM) impairments. However, it is unclear how the NAcSh is involved in these spatial deficits. To address this, we evaluated the impact of unilateral local NAcSh electrical lesions during the execution of a food-reinforced eight-shaped spatial alternation WM task. Behavioral performance was assessed in rats after the onset of the neuropathic pain model—spared nerve injury (SNI). Our findings indicate that the induction of SNI and/or NAcSh lesions did not significantly impact the animals’ performance accuracy or motor activity during the execution of the behavioral task, but altered their response latency patterns. In addition, these manipulations did not induce significant antinociceptive effects. Collectively, these results suggest that the NAcSh may participate in specific aspects of spatial information integration and processing under neuropathic pain conditions. Full article
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15 pages, 2290 KiB  
Article
Potential Food Inclination of Crab-Eating Macaques in Laboratory Environments: Enhancing Positive Reinforcement Training and Health Optimization
by Ji Woon Kim, Yoon Beom Lee, Yeon Su Hong, Hoesu Jung and Gwang-Hoon Lee
Animals 2024, 14(7), 1123; https://doi.org/10.3390/ani14071123 - 7 Apr 2024
Viewed by 2216
Abstract
Positive reinforcement and training for health optimization are pivotal for successful studies with monkeys. Potential food inclination is important for studies on crab-eating macaques in laboratory environments, but evaluations remain scarce. We explored crab-eating macaques’ potential food inclination to establish a reward system [...] Read more.
Positive reinforcement and training for health optimization are pivotal for successful studies with monkeys. Potential food inclination is important for studies on crab-eating macaques in laboratory environments, but evaluations remain scarce. We explored crab-eating macaques’ potential food inclination to establish a reward system for future behavioral assessments. Twelve male and three female monkeys underwent a food inclination assessment in which they were offered four food categories—fruits, vegetables, proteins, and nuts. The monkeys exhibited a higher inclination for plant-based foods, particularly fruits and vegetables, over animal-based proteins like chicken and tuna (p < 0.0001), with a notable inclination for nuts (eaten/provided = 100%). Additionally, the consistency of potential food inclination after repeated offerings was investigated, revealing a time-dependent increase in inclination for protein items. Food consumption ratios correlated positively with caloric intake (r = 0.59, p = 0.02), implying that individuals with a regular high caloric intake and increased body weight are more likely to accept food during positive reinforcement training. Our findings suggest fruits, vegetables, protein-rich foods, and nuts can help with health optimization. However, animal-based protein-rich foods initially had a low preference, which may increase over time. Our study can provide guidelines for positive reinforcement training and health optimization. Full article
(This article belongs to the Special Issue Care and Well-Being of Laboratory Animals)
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17 pages, 16909 KiB  
Article
Adaptive Locomotion Learning for Quadruped Robots by Combining DRL with a Cosine Oscillator Based Rhythm Controller
by Xiaoping Zhang, Yitong Wu, Huijiang Wang, Fumiya Iida and Li Wang
Appl. Sci. 2023, 13(19), 11045; https://doi.org/10.3390/app131911045 - 7 Oct 2023
Cited by 3 | Viewed by 3157
Abstract
Animals have evolved to adapt to complex and uncertain environments, acquiring locomotion skills for diverse surroundings. To endow a robot’s animal-like locomotion ability, in this paper, we propose a learning algorithm for quadruped robots based on deep reinforcement learning (DRL) and a rhythm [...] Read more.
Animals have evolved to adapt to complex and uncertain environments, acquiring locomotion skills for diverse surroundings. To endow a robot’s animal-like locomotion ability, in this paper, we propose a learning algorithm for quadruped robots based on deep reinforcement learning (DRL) and a rhythm controller that is based on a cosine oscillator. For a quadruped robot, two cosine oscillators are utilized at the hip joint and the knee joint of one leg, respectively, and, finally, eight oscillators form the controller to realize the quadruped robot’s locomotion rhythm during moving. The coupling between the cosine oscillators of the rhythm controller is realized by the phase difference, which is simpler and easier to realize when dealing with the complex coupling relationship between different joints. DRL is used to help learn the controller parameters and, in the reward function design, we address the challenge of terrain adaptation without relying on the complex camera-based vision processing but based on the proprioceptive information, where a state estimator is introduced to achieve the robot’s posture and help finally utilize the food-end coordinate. Experiments are carried out in CoppeliaSim, and all of the flat, uphill and downhill conditions are considered. The results show that the robot can successfully accomplish all the above skills and, at the same time, with the reward function designed, the robot’s pitch angle, yaw angle and roll angle are very small, which means that the robot is relatively stable during walking. Then, the robot is transplanted to a new scene; the results show that although the environment is previously unencountered, the robot can still fulfill the task, which demonstrates the effectiveness and robustness of this proposed method. Full article
(This article belongs to the Special Issue Intelligent Control and Robotics II)
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18 pages, 2835 KiB  
Article
Optimizing Controlled Environmental Agriculture for Strawberry Cultivation Using RL-Informer Model
by Yuze Lu, Mali Gong, Jing Li and Jianshe Ma
Agronomy 2023, 13(8), 2057; https://doi.org/10.3390/agronomy13082057 - 3 Aug 2023
Cited by 6 | Viewed by 3250
Abstract
Controlled Environmental Agriculture (CEA) has gained a lot of attention in recent years, mainly because of its ability to overcome extreme weather problems and ensure food safety. CEA can meet the full growth state monitoring of the crop period; however, the optimization of [...] Read more.
Controlled Environmental Agriculture (CEA) has gained a lot of attention in recent years, mainly because of its ability to overcome extreme weather problems and ensure food safety. CEA can meet the full growth state monitoring of the crop period; however, the optimization of the growing environment is still limited by the algorithm defects. In this article, we present an optimization method of growing environment based on reinforcement learning, Q-learning and the time-series prediction model Informer. This approach is demonstrated for the first time as far as we know. By employing Informer, we predicted the growth of strawberries based on current environmental variables and plant status. The prediction results served as a reward to motivate Q-learning, guiding it to make optimal modifications to the environment in real-time. This approach aimed to achieve the optimal cultivation environment continuously. Two groups of validation experiments were conducted based on different cultivation objectives: “obtaining the most stolons” and “obtaining the highest fruit count”. Compared to the empirically planted groups, the experimental groups using the RL-Informer model achieved yield increases of 17.81% and 20.78%, respectively. These experiments highlight the outstanding performance of the proposed RL-Informer model in real-time prediction and modification of environmental variables. Full article
(This article belongs to the Section Precision and Digital Agriculture)
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27 pages, 4456 KiB  
Article
A Quantitative Assessment of Trainers-Dolphins’ Interactions in the Absence of Food Reward
by Sara Platto and Agathe Serres
Animals 2023, 13(10), 1651; https://doi.org/10.3390/ani13101651 - 16 May 2023
Cited by 5 | Viewed by 2428
Abstract
All the studies that have considered the motivation of the dolphins to interact with their trainers as a possible welfare indicator have been carried out in facilities where the trainer-dolphin interactions (TDIs) sessions were reinforced with food. Therefore, in these specific circumstances, it [...] Read more.
All the studies that have considered the motivation of the dolphins to interact with their trainers as a possible welfare indicator have been carried out in facilities where the trainer-dolphin interactions (TDIs) sessions were reinforced with food. Therefore, in these specific circumstances, it was difficult to separate the motivation of the dolphins interacting with the trainers from the food drive. The current study aims to assess the interaction between the trainers and the dolphins in the absence of food rewards. The research was carried out at The Dolphin Reef (Eilat, Israel), a facility where the interaction between the trainers and 14 bottlenose dolphins of different sex and age classes did not involve food rewards. A total of 531 TDIs were recorded, with dolphins participating in 94.5% of the sessions and an average of three dolphins per session. The dolphins participated in a higher number and more frequently in the TDIs when toys were provided by the trainers. Diel and seasonal differences were also observed, with the dolphins participating more during the morning sessions and the neutral season. The latency of response of the dolphins to the presence of the trainers on the platform or in the water, whether or not advertised by the trainers’ signal (“call” or “no-call”), was very short (usually less than 1 min), and the dolphins often anticipated the beginning of the sessions by arriving at the trainers’ location before or upon the caretakers’ arrival (96% of the time). Individual differences in the participation in the TDIs were also recorded, which might be linked to both the dolphin’s health/welfare status or their personality. The current study shows that the separation of the TDIs from the food reward allows for a better understanding of the willingness of dolphins under human care to interact with their trainers. In addition, the results presented in this paper show that such TDIs are an important part of these dolphins’ lives, which suggests that these interactions might be an additional tool to improve the animals’ social environment and monitor their welfare. Full article
(This article belongs to the Section Human-Animal Interactions, Animal Behaviour and Emotion)
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19 pages, 376 KiB  
Review
Could Alcohol Abuse and Dependence on Junk Foods Inducing Obesity and/or Illicit Drug Use Represent Danger to Liver in Young People with Altered Psychological/Relational Spheres or Emotional Problems?
by Giovanni Tarantino, Mauro Cataldi and Vincenzo Citro
Int. J. Mol. Sci. 2022, 23(18), 10406; https://doi.org/10.3390/ijms231810406 - 8 Sep 2022
Cited by 18 | Viewed by 6092
Abstract
Recent data show that young people, mainly due to the pressure of some risk factors or due to disrupted interpersonal relationships, utilise greater reward value and display greater sensitivity to the reinforcing properties of “pleasurable stimuli”, specifically in those situations in which an [...] Read more.
Recent data show that young people, mainly due to the pressure of some risk factors or due to disrupted interpersonal relationships, utilise greater reward value and display greater sensitivity to the reinforcing properties of “pleasurable stimuli”, specifically in those situations in which an enhanced dopamine release is present. Alcoholic beverages, foods rich in sugar and fat, and illicit drug use are pleasurable feelings associated with rewards. Research shows that there is a link between substance abuse and obesity in brain functioning. Still, alcohol excess is central in leading to obesity and obesity-related morbidities, such as hepatic steatosis, mainly when associated with illicit drug dependence and negative eating behaviours in young people. It is ascertained that long-term drinking causes mental damage, similarly to drug abuse, but also affects liver function. Indeed, beyond the pharmacokinetic interactions of alcohol with drugs, occurring in the liver due to the same metabolic enzymes, there are also pharmacodynamic interactions of both substances in the CNS. To complicate matters, an important noxious effect of junk foods consists of inducing obesity and obesity-related NAFLD. In this review, we focus on some key mechanisms underlying the impact of these addictions on the liver, as well as those on the CNS. Full article
15 pages, 1295 KiB  
Article
Using Classical and Operant Conditioning to Train a Shifting Behavior in Juvenile False Water Cobras (Hydrodynastes gigas)
by Michelle L. Williams, Lori A. Torrini, E. Joseph Nolan and Zachary J. Loughman
Animals 2022, 12(10), 1229; https://doi.org/10.3390/ani12101229 - 10 May 2022
Cited by 6 | Viewed by 9718
Abstract
All animals have the capacity to learn through operant conditioning and other types of learning, and as a result, zoos and other animal care facilities have shifted towards the use of positive reinforcement training to shape the behavior of animals under their care. [...] Read more.
All animals have the capacity to learn through operant conditioning and other types of learning, and as a result, zoos and other animal care facilities have shifted towards the use of positive reinforcement training to shape the behavior of animals under their care. Training offers animals the choice to participate in their own husbandry routines and veterinary procedures, while also providing mental stimulation. By adopting these practices, the welfare of animals in human care has improved, but it has not been applied equally across taxa. Snakes are frequently overlooked in the discussion of choice and control in a captive setting, likely due to the historical misinterpretation of their intelligence and behavioral needs. In this study, a shaping plan was developed for 28 juvenile false water cobras (Hydrodynastes gigas), a rear-fanged venomous species, from four clutches. Snakes were rewarded with food when completing behaviors related to the ultimate goal of following a target into a shift container. The purpose of this study is to incorporate the trained behaviors in routine husbandry practices, while preventing unnecessary stress in the snakes and risk to the keeper. Full article
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25 pages, 28236 KiB  
Article
Quantifying Reinforcement-Learning Agent’s Autonomy, Reliance on Memory and Internalisation of the Environment
by Anti Ingel, Abdullah Makkeh, Oriol Corcoll and Raul Vicente
Entropy 2022, 24(3), 401; https://doi.org/10.3390/e24030401 - 13 Mar 2022
Cited by 3 | Viewed by 2799
Abstract
Intuitively, the level of autonomy of an agent is related to the degree to which the agent’s goals and behaviour are decoupled from the immediate control by the environment. Here, we capitalise on a recent information-theoretic formulation of autonomy and introduce an algorithm [...] Read more.
Intuitively, the level of autonomy of an agent is related to the degree to which the agent’s goals and behaviour are decoupled from the immediate control by the environment. Here, we capitalise on a recent information-theoretic formulation of autonomy and introduce an algorithm for calculating autonomy in a limiting process of time step approaching infinity. We tackle the question of how the autonomy level of an agent changes during training. In particular, in this work, we use the partial information decomposition (PID) framework to monitor the levels of autonomy and environment internalisation of reinforcement-learning (RL) agents. We performed experiments on two environments: a grid world, in which the agent has to collect food, and a repeating-pattern environment, in which the agent has to learn to imitate a sequence of actions by memorising the sequence. PID also allows us to answer how much the agent relies on its internal memory (versus how much it relies on the observations) when transitioning to its next internal state. The experiments show that specific terms of PID strongly correlate with the obtained reward and with the agent’s behaviour against perturbations in the observations. Full article
(This article belongs to the Special Issue Towards a Quantitative Understanding of Agency)
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18 pages, 2574 KiB  
Article
Rat 50 kHz Trill Calls Are Tied to the Expectation of Social Interaction
by Candace J. Burke, Mariya Markovina, Sergio M. Pellis and David R. Euston
Brain Sci. 2021, 11(9), 1142; https://doi.org/10.3390/brainsci11091142 - 28 Aug 2021
Cited by 15 | Viewed by 3068
Abstract
Rats emit a variety of calls in the 40–80 kHz range (50 kHz calls). While these calls are generally associated with positive affect, it is unclear whether certain calls might be used selectively in certain contexts. To examine this, we looked at ultrasonic [...] Read more.
Rats emit a variety of calls in the 40–80 kHz range (50 kHz calls). While these calls are generally associated with positive affect, it is unclear whether certain calls might be used selectively in certain contexts. To examine this, we looked at ultrasonic calls in 30–40 day old male rats during the expectation of either play or food, both of which are reinforcing. Behavior and vocalizations were recorded while rats were in a test chamber awaiting the arrival of a play partner or food over seven days of testing. Control groups were included for the non-specific effects of food deprivation and social isolation. Play reward led to an increase in 50 kHz vocalizations, generally, with specific increases in trill and “trill with jump” calls not seen in other groups. Expectation of food reward did not lead to a significant increase in vocalizations of any type, perhaps due to the young age of our study group. Further, rats that were food deprived for the food expectation study showed markedly lower calls overall and had a different profile of call types compared to rats that were socially isolated. Taken together, the results suggest that trill-associated calls may be used selectively when rats are socially isolated and/or expecting a social encounter. Full article
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18 pages, 2488 KiB  
Article
Olfactory Learning Supports an Adaptive Sugar-Aversion Gustatory Phenotype in the German Cockroach
by Ayako Wada-Katsumata and Coby Schal
Insects 2021, 12(8), 724; https://doi.org/10.3390/insects12080724 - 13 Aug 2021
Cited by 2 | Viewed by 4585
Abstract
An association of food sources with odors prominently guides foraging behavior in animals. To understand the interaction of olfactory memory and food preferences, we used glucose-averse (GA) German cockroaches. Multiple populations of cockroaches evolved a gustatory polymorphism where glucose is perceived as a [...] Read more.
An association of food sources with odors prominently guides foraging behavior in animals. To understand the interaction of olfactory memory and food preferences, we used glucose-averse (GA) German cockroaches. Multiple populations of cockroaches evolved a gustatory polymorphism where glucose is perceived as a deterrent and enables GA cockroaches to avoid eating glucose-containing toxic baits. Comparative behavioral analysis using an operant conditioning paradigm revealed that learning and memory guide foraging decisions. Cockroaches learned to associate specific food odors with fructose (phagostimulant, reward) within only a 1 h conditioning session, and with caffeine (deterrent, punishment) after only three 1 h conditioning sessions. Glucose acted as reward in wild type (WT) cockroaches, but GA cockroaches learned to avoid an innately attractive odor that was associated with glucose. Olfactory memory was retained for at least 3 days after three 1 h conditioning sessions. Our results reveal that specific tastants can serve as potent reward or punishment in olfactory associative learning, which reinforces gustatory food preferences. Olfactory learning, therefore, reinforces behavioral resistance of GA cockroaches to sugar-containing toxic baits. Cockroaches may also generalize their olfactory learning to baits that contain the same or similar attractive odors even if they do not contain glucose. Full article
(This article belongs to the Collection Insect Sensory Biology)
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