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Concept: Reinforcement


Dopamine signaling is implicated in reinforcement learning, but the neural substrates targeted by dopamine are poorly understood. We bypassed dopamine signaling itself and tested how optogenetic activation of dopamine D1 or D2 receptor–expressing striatal projection neurons influenced reinforcement learning in mice. Stimulating D1 receptor–expressing neurons induced persistent reinforcement, whereas stimulating D2 receptor–expressing neurons induced transient punishment, indicating that activation of these circuits is sufficient to modify the probability of performing future actions.

Concepts: Reinforcement, Reinforcement learning, Dopamine, Neurotransmitter, Operant conditioning, Nervous system, Neuron, Dopamine receptor


The reward system is a collection of circuits that reinforce behaviors necessary for survival [1, 2]. Given the importance of reproduction for survival, actions that promote successful mating induce pleasurable feeling and are positively reinforced [3, 4]. This principle is conserved in Drosophila, where successful copulation is naturally rewarding to male flies, induces long-term appetitive memories [5], increases brain levels of neuropeptide F (NPF, the fly homolog of neuropeptide Y), and prevents ethanol, known otherwise as rewarding to flies [6, 7], from being rewarding [5]. It is not clear which of the multiple sensory and motor responses performed during mating induces perception of reward. Sexual interactions with female flies that do not reach copulation are not sufficient to reduce ethanol consumption [5], suggesting that only successful mating encounters are rewarding. Here, we uncoupled the initial steps of mating from its final steps and tested the ability of ejaculation to mimic the rewarding value of full copulation. We induced ejaculation by activating neurons that express the neuropeptide corazonin (CRZ) [8] and subsequently measured different aspects of reward. We show that activating Crz-expressing neurons is rewarding to male flies, as they choose to reside in a zone that triggers optogenetic stimulation of Crz neurons and display conditioned preference for an odor paired with the activation. Reminiscent of successful mating, repeated activation of Crz neurons increases npf levels and reduces ethanol consumption. Our results demonstrate that ejaculation stimulated by Crz/Crz-receptor signaling serves as an essential part of the mating reward mechanism in Drosophila. VIDEO ABSTRACT.

Concepts: Insect, Neuropeptide, Female, Induced demand, Male, Reproduction, Reinforcement, Sex


Noncontingent reinforcement (NCR) is the response-independent delivery of a reinforcer (Vollmer, Iwata, Zarcone, Smith, and Mazaleski in Journal of Applied Behavior Analysis 26: 9-21 1993). Two staff members (preservice education majors) implemented NCR procedures for two students with autism spectrum disorder (ASD) who exhibited problem behavior and attended an after-school program. The amount of training on NCR and procedural fidelity was measured for each staff member, and the effects of the treatment on problem behavior were evaluated. Results indicate NCR is a low-effort procedure that reduced problem behavior of two participants with ASD. • NCR can both reduce problem behaviors of clients who engage in difficult behaviors (Carr, Severtson, & Lepper, 2009). • NCR can be used for clients for whom extinction-induced behaviors are dangerous (Tucker, Sigafoos, and Bushell in Behavior Modification, 22: 529-547, 1998). • Nonbehavioral providers can implement NCR with high fidelity, making it a good procedure to use when collaborating with other professionals (teachers, SLP, parents, etc.; Matson, 2009). • NCR can be used when clinicians first begin working with a client until more detailed interventions are created.

Concepts: Experimental analysis of behavior, Autism, Reinforcement, Autism spectrum, Operant conditioning, Behavior, Behaviorism, Applied behavior analysis


The behavioral management of laboratory nonhuman primates in the United States has not been thoroughly characterized since 2003. This article presents the results of a survey behavioral management programs at 27 facilities and covering a total of 59,636 primates, 27,916 housed in indoor cages and 31,720 in group enclosures. The survey included questions regarding program structure, implementation, and methodology associated with social housing, positive reinforcement training, positive human interaction, exercise enclosures, and several categories of inanimate enrichment. The vast majority of laboratory primates are housed socially (83%). Since 2003, the proportion of indoor-housed primates reported to be housed singly has fallen considerably, from 59% to 35% in the facilities surveyed. The use of social housing remains significantly constrained by: 1) research protocol requirements, highlighting the value of closely involved IACUCs for harmonizing research and behavioral management; and 2) the unavailability of compatible social partners, underscoring the necessity of objective analysis of the methods used to foster and maintain compatibility. Positive reinforcement training appears to have expanded and is now used at all facilities responding to the survey. The use of enrichment devices has also increased in the participating facilities. For most behavioral management techniques, concerns over the possibility of negative consequences to animals are expressed most frequently for social housing and destructible enrichment, while skepticism regarding efficacy is limited almost exclusively to sensory enrichment. Behavioral management program staffing has expanded over time in the facilities surveyed, due not only to increased numbers of dedicated behavioral management technicians but also to greater involvement of animal care technicians, suggesting an increase in the integration of behavioral care into animal husbandry. Broad awareness of common practice may assist facilities with program evaluation and assessment of progress in the field can generate recommendations for continuing the advancement of primate behavioral management programs. Am. J. Primatol. © 2016 Wiley Periodicals, Inc.

Concepts: Reinforcement, Surveying, Program, Evaluation, Animal, United States, Program management, Primate


Smoking tobacco remains one of the leading causes of preventable deaths in North America. Nicotine reinforces smoking behavior, in part, by enhancing the reinforcing properties of reward-related stimuli, or conditioned stimuli (CSs), associated with tobacco intake. To investigate how pharmaceutical interventions may affect this property of nicotine, we examined the effect of four US Food and Drug Administration (FDA) approved drugs on the ability of nicotine to enhance operant responding for a CS as a conditioned reinforcer. Thirsty rats were exposed to 13 Pavlovian sessions where a CS was paired with water delivery. Nicotine (0.4 mg/kg) injections were administered before each Pavlovian session. Then, in separate groups of rats, the effects of varenicline (1 mg/kg), bupropion (10 and 30 mg/kg), lorcaserin (0.6 mg/kg), and naltrexone (2 mg/kg), and their interaction with nicotine on responding for conditioned reinforcement were examined. Varenicline and lorcaserin each reduced nicotine-enhanced responding for conditioned reinforcement, whereas naltrexone had a modest effect of reducing response enhancements by nicotine. In contrast, bupropion enhanced the effect of nicotine on this measure. The results of these studies may inform how pharmaceutical interventions can affect smoking cessation attempts and relapse through diverse mechanisms, either substituting for, or interacting with, the reinforcement-enhancing properties of nicotine.

Concepts: Reward system, Punishment, Tobacco, Extinction, Smoking cessation, Nicotine, Operant conditioning, Reinforcement


Hernia repairs in contaminated fields are often reinforced with a bioprosthetic mesh. When choosing which of the multiple musculofascial abdominal wall planes provides the most durable repair, there is little guidance. We hypothesized that the retro-rectus plane would reduce recurrence rates versus intraperitoneal placement due to greater surface area contact of mesh with well-vascularized tissue.

Concepts: Hernias, Surface area, Reinforcement, Area, Pediatric surgery, Surgery, Hernia


Reward enhancement by nicotine has been suggested as an important phenomenon contributing toward tobacco abuse and dependence. Reinforcement value is a multifaceted construct not fully represented by any single measure of response strength. The present study evaluated the changes in the reinforcement value of a visual stimulus in 16 male Sprague-Dawley rats using the reinforcer demand technique proposed by Hursh and Silberberg. The different parameters of the model have been shown to represent differing facets of reinforcement value, including intensity, perseverance, and sensitivity to changes in response cost. Rats lever-pressed for 1-min presentations of a compound visual stimulus over blocks of 10 sessions across a range of response requirements (fixed ratio 1, 2, 4, 8, 14, 22, 32). Nicotine (0.4 mg/kg, base) or saline was administered 5 min before each session. Estimates from the demand model were calculated between nicotine and saline administration conditions within subjects and changes in reinforcement value were assessed as differences in Q0, Pmax, Omax, and essential value. Nicotine administration increased operant responding across the entire range of reinforcement schedules tested, and uniformly affected model parameter estimates in a manner suggesting increased reinforcement value of the visual stimulus.

Concepts: Punishment, Experimental analysis of behavior, Matching law, Nicotine, Parameter, Operant conditioning, Reward system, Reinforcement


The classic nanocomposite approach aims at percolation of low fraction of exfoliated individual reinforcing nanoscale elements within a polymeric matrix. By contrast, many of the mechanically excellent biological nanocomposites involve self-assembled and space-filled structures of hard reinforcing and soft toughening domains, with high weight fraction of reinforcements. Here we inspect a new concept towards mimicking such structures by studying whether percolation of intercalated domains consisting of alternating rigid and reinforcing, and soft rubbery domains could allow a transition to a reinforced state. Towards that, we present the functionalization of rigid native cellulose nanocrystals (CNC) by esterification with a dense hydrocarbon chain brush containing cross-linkable double bonds. Composite films with 0-80 wt% of such modified CNCs (mCNC) within a poly(butadiene) (PBD) rubber matrix were prepared via cross-linking by UV-light initiated thiol-ene click reaction. Transmission electron microscopy showed structures at two length scales, where the mCNCs and PBD form domains having internal aligned self-assemblies of alternating hard mCNCs and soft PBD with periodicity of 40 nm, and where additional PBD connects such domains. Increasing the weight fraction of mCNCs causes an uncommon abrupt transition from PBD-dominated soft materials to significantly reinforced mCNC-dominated mechanical properties, suggesting that the intercalated self-assembled mCNC/PBD domains percolate in PBD upon passing 30-35 wt% of mCNCs. Maximum stress of 16 MPa at mCNC fraction 80 wt% was obtained. The mechanical properties of the composites show exceptional insensitivity to air humidity. The shown simple concept of percolative intercalated nanocomposites suggests searching for more general biomimetic compositions involving several deformation mechanisms for improved mechanical properties.

Concepts: Percolation threshold, Click chemistry, Electron, Reinforcement, Percolation


RATIONALE: The orexin (Orx)/hypocretin system has been implicated in reward-seeking, especially for highly salient food and drug rewards. We recently demonstrated that signaling at the OxR1 receptor is involved in sucrose reinforcement and reinstatement of sucrose-seeking elicited by sucrose-paired cues in food-restricted rats. Because sucrose reinforcement has both a hedonic and caloric component, it remains unknown what aspect of this reward drives its reinforcing value. OBJECTIVES: The present study examined the involvement of the Orx system in operant responding for saccharin, a noncaloric, hedonic (sweet) reward, and in cue-induced reinstatement of extinguished saccharin-seeking in ad libitum-fed vs food-restricted male subjects. METHODS: Male Sprague Dawley rats were fed ad libitum or food-restricted and trained to self-administer saccharin. We determined the effects of pretreatment with the OxR1 receptor antagonist SB-334867 (SB; 10-30 mg/kg) on fixed ratio (FR) saccharin self-administration and on cue-induced reinstatement of extinguished saccharin-seeking. RESULTS: SB decreased responding and number of reinforcers earned during FR responding for saccharin and decreased cue-induced reinstatement of extinguished saccharin-seeking. All of these effects were obtained similarly in food-restricted and ad libitum-fed rats. CONCLUSIONS: These results indicate that signaling at the OxR1 receptor is involved in saccharin reinforcement and reinstatement of saccharin-seeking elicited by saccharin-paired cues regardless of food restriction. These findings lead us to conclude that the Orx system contributes to the motivational effects of hedonic food rewards, independently of caloric value and homeostatic needs.

Concepts: Receptor antagonist, Receptor, Punishment, Laboratory rat, Operant conditioning, Reinforcement, Reward system


Prior work with chelonians has demonstrated their capacity for successful performance in cognitive tasks, including those requiring color discrimination. Here, we sought to expand on historical research and determine whether eastern box turtles (Terrapene carolina) are capable of not only making simple color discriminations but also whether they can demonstrate abstract concept formation evidenced by using a relational response rule in their discrimination performance. Two eastern box turtles were rapidly and successfully trained on a black-and-white two-choice discrimination task using painted paddles and food reinforcement. After mastery, a medium gray paddle was added as a choice stimulus and turtle “Flippy” was reinforced for selecting the darker of the 2 stimuli presented in each trial, and turtle “Mario” was reinforced for selecting the lighter of the paddles presented. Nonreinforced probe trials incorporating light and dark gray stimuli paired with all other color options were then added to each session to test the turtles' ability to use the relationship between choice stimuli to guide responding. The turtles successfully selected the paddles corresponding to their assigned relational response rule of “darker” or “lighter” at a level significantly above that predicted by chance. The turtles then demonstrated immediate generalization of their relational rule in testing with a novel array of blue paddles. Finally, the turtles continued to use their relational rule when presented with a novel array of green paddles in a traditional transposition task. Together, these findings support the capacity for higher order cognitive functioning in chelonians beyond that previously described. (PsycINFO Database Record © 2013 APA, all rights reserved).

Concepts: All rights reserved, Cognition, Terrapene, Reinforcement, The Turtles, Turtle, Turtles, Box turtle