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BACKGROUND: Manganese (Mn) is essential to healthy neurodevelopment, but both Mn deficiency and over-exposure have been linked to prefrontal cortex (PFC) impairments, the brain region that regulates cognitive and neurobehavioral processes responsible for spatial memory, learning, motivation, and time perception. These processes facilitated by attention, inhibitory control, working memory, and cognitive flexibility are often sexually dimorphic and complex, driven by multiple interconnected neurologic and cognitive domains. OBJECTIVE: We investigated the role of child sex as an effect modifier of the association between prenatal Mn exposure and performance in an operant testing battery (OTB) that assessed multiple cognitive and behavioral functional domains. METHODS: Children (N = 575) aged 6-8 years completed five OTB tasks. Blood and urinary Mn measurements were collected from mothers in the 2nd and 3rd trimesters. Multiple regression models estimated the association between Mn biomarkers at each trimester with OTB performance while adjusting for socio-demographic covariates. Covariate-adjusted weighted quantile sum (WQS) regression models were used to estimate the association of a Mn multi-media biomarker (MMB) mixture with OTB performance. Interaction terms were used to estimate modification effect by child sex. RESULTS: Higher blood Mn exposure was associated with better response rates (more motivation) on the progressive ratio task and higher overall accuracy on the delayed matching-to-sample task. In the WQS models, the MMB mixture was associated with better response rates (more motivation) on the progressive ratio task. Additionally, for the linear and WQS models, we observed a modification effect by child sex in the progressive ratio and delayed matching-to-sample tasks. Higher prenatal Mn biomarker levels were associated with improved task performance for girls and reduced performance in boys. CONCLUSION: Higher prenatal blood Mn concentrations and the MMB mixture predicted improved performance on two of five operant tasks. Higher prenatal Mn concentrations regulated executive functions in children in a sexually dimorphic manner. Higher prenatal Mn exposure is associated with improved performance on spatial memory and motivation tasks in girls, suggesting that Mn's nutritional role is sexually dimorphic, and should be considered when making dietary and/or environmental intervention recommendations.

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Background: Temporomandibular joint (TMJ)-associated inflammation contributes to the pain reported by patients with temporomandibular disorders (TMD). It is common for patients diagnosed with TMD to report pain in the masticatory muscles and temporomandibular joints, headache, and jaw movement disturbances. Although TMD can have different origins, including trauma and malocclusion disorder, anxiety/depression substantially impacts the development and maintenance of TMD. In general, rodent studies on orofacial pain mechanisms involve the use of tests originally developed for other body regions, which were adapted to the orofacial area. To overcome limitations and expand knowledge in orofacial pain, our group validated and characterized an operant assessment paradigm in rats with both hot and cold stimuli as well mechanical stimuli. Nevertheless, persistent inflammation of the TMJ has not been evaluated with this operant orofacial pain assessment device (OPAD). Methods: We characterized the thermal orofacial sensitivity for cold, neutral, and hot stimuli during the development of TMD using the OPAD behavior test. In addition, we evaluated the role of transient receptor potential vanilloid 1 (TRPV1) expressing nociceptors in rats with persistent TMJ inflammation. The experiments were performed in male and female rats with TMJ inflammation induced by carrageenan (CARR). Additionally, resiniferatoxin (RTX) was administered into the TMJs prior CARR to lesion TRPV1-expressing neurons to evaluate the role of TRPV1-expressing neurons. Results: We evidenced an increase in the number of facial contacts and changes in the number of reward licks per stimulus on neutral (37°C) and cold (21°C) temperatures. However, at the hot temperature (42°C), the inflammation did not induce changes in the OPAD test. The prior administration of RTX in the TMJ prevented the allodynia and thermal hyperalgesia induced by CARR. Conclusion: We showed that TRPV-expressing neurons are involved in the sensitivity to carrageenan-induced pain in male and female rats evaluated in the OPAD.

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Two free operant conditioning experiments with rats examined the impact of conducting a large amount of extinction training on situations that enhance the ABC renewal effect (ABC super renewal). In Experiment 1, ABC renewal was strengthened by conducting acquisition in multiple contexts. All rats were trained to press a lever for food. One group was trained in one context, while the other two groups were trained in three contexts. Then, all rats received extinction in context B. For two groups this phase lasted 4 sessions, whereas it lasted 36 sessions for the other group. In Experiment 2, ABC renewal was strengthened by using a large number of acquisition sessions. Rats were trained to perform an operant response to obtain food in context A. One group received a moderate amount of training, while the rest of the rats received a larger number of acquisition sessions. Responses underwent extinction in context B. Two groups received 4 sessions, while 36 extinction sessions were used for the remaining group. In both experiments, rats were tested in context B (extinction context) and C (renewal context). Greater ABC renewal occurred both when acquisition training was conducted in multiple contexts (Experiment 1) and by increasing the amount of acquisition training (Experiment 2). Nevertheless, we found that conducting a large number of extinction sessions reduced ABC super renewal in Experiment 1 only.

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Conditioned drug cues can evoke brief drug-like responses. In this report we show that using brief test sessions, contextual cues can induce conditioned hyperlocomotion and ERK responses equivalent to morphine induced responses. To assess acute unconditioned effects, rats that received morphine (MOR-1) or vehicle (VEH-1) were immediately placed onto an arena for a 5-min locomotion recording session after which ERK was measured in the ventral tegmental area (VTA) and nucleus accumbens (NAc). There were no differences in locomotion between the groups. However, the MOR-1 group had strong ERK activation in VTA and NAc. To assess MOR-conditioned effects, a chronic phase was carried out according to a Pavlovian conditioning protocol. There were two MOR paired groups (MORP), one MOR unpaired (MOR-UP) group and two VEH groups. The treatments were administered over 5 daily five minute test sessions. The final conditioning test was on day 6, in which one of the MOR-P groups and one of the VEH groups received VEH (MOR-P/VEH-6 and VEH/VEH-6, respectively). The other MOR-P group and VEH group received MOR (MOR-P/MOR; VEH/MOR-6, respectively). The MOR-UP group received VEH (MOR-UP/VEH-6). Rats received the treatments immediately prior to a 5-minute arena test, and after the session ERK was measured. No morphine induced locomotor stimulation was observed on day 1 but on days 2 to 5, hyperlocomotion in both MOR-P groups occurred. On test day 6, the MOR-P/VEH-6 and the MOR-P/MOR-6 groups had comparable locomotor stimulant responses and similar ERK activity in the VTA and NAc. The MOR-UP group did not differ from the VEH group. We suggest that ERK activation evoked by acute morphine served as a Pavlovian unconditioned stimulus to enable the contextual cues to acquire morphine conditioned stimulus properties and increase the incentive value of the contextual cues.

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We used an operant conditioning paradigm to test the motivation of non-pregnant dairy heifers to access shade during the summer and autumn months (January to June) in southern Brazil. Dairy heifers (n = 18) were trained to push a weighted gate to access either an experimental area containing both a shaded (simple tree shade and shade cloth) and unshaded area (WITH SHADE) or an experimental area with no shade (BARREN). The latency to push the weighted gate, and the maximum weight pushed by each heifer, were recorded in both the summer and the autumn. Temperature and humidity were recorded continuously for the duration of the study and were used to calculate the heat index. The maximum weight pushed to enter the WITH SHADE area was greater in summer than in autumn, and was inversely related to the latency to push the weighted gate. Heifers refused to work for access to the BARREN environment. As expected, both the maximum ambient temperatures and heat index were higher in summer than in autumn, and also higher in the non-shaded areas than under the shade in both seasons. Heifers of higher social rank displaced other heifers more often, and spent more time in the shaded areas, particularly in the area with trees plus a shade cloth, than the intermediate and subordinate heifers. We conclude that shade is an important and valued resource for heifers reared on pasture-based systems in sub-tropical environments, particularly during the hot summer months.

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The development of sensitization is one of the hallmarks of addictive drugs such as morphine. We administered morphine (10 mg/kg; MOR) to induce locomotor sensitization and ERK activation in the VTA and NAc. In the first experiment, four groups of rats received five daily 30 min sessions in an open-field, and locomotion was measured. For the first four sessions, one group received MOR pre-test (MOR-P); a second group received vehicle pre-test (MOR-UP) and MOR 30 min post-test; the remaining 2 groups received vehicle (VEH) pre-test. On the fifth session, the MOR-P, MOR-UP, and one VEH group received MOR pre-test and the remaining VEH group received VEH. Sensitization emerged in the first 5 min and progressed over to the second and third 5 min blocks only in the MOR-P group. For the second experiment, 4 groups received MOR and 4 groups VEH, and were then returned to their home cage and after 5, 15, 30 or 60 min post-injection, were euthanized for ERK measurements in VTA and NAc. ERK activation increased and peaked at 5 min post injection in the MOR group and then declined to VEH levels by 30 min. Another two groups received either MOR or VEH immediately before a 5 min arena test and ERK was measured immediately post-test. MOR had no effect on locomotion but increased ERK in the VTA and NAc. The peak ERK activation in VTA reflected activation of reward systems by morphine that reinforced locomotor behavior and with repeated treatments, induced a sensitization effect.

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BACKGROUND: Ethanol exposure at early ontogeny promotes further predisposition to consume the drug. Operant conditioning allows motivational alcohol properties to be assessed. To date, the operant conditioning approach used during infancy consisted in paired subjects being trained to learn an operant response, using simultaneously a yoked partner, which received reinforcer solution as a result of a paired animal instrumental response (OYS). NEW METHOD: In our study, we attempted to evaluate ethanol reinforcing effects during PDs 15-18 in an operant conditioning schedule with a stimulus discrimination procedure (OSD), as an alternative control learning. This new proposal includes a single subject, who has to choose between an S+ nose-poke hole, which delivers the reinforcer into the mouth, or an S- nose-poke hole with no reinforcement effect. RESULTS: The OSD results seemed to be more reliable than those obtained using the OYS procedure, since some data appeared to be more robust when using a yoked nose-poke hole than when employing a yoked subject, such as in control learning. Consequently, OSD has the following advantages compared to the OYS procedure: a) the operant response learned is controlled by the overall behavior of the same subject, resulting in a relatively clearer data; b) a yoked animal is not necessary, thereby reducing the number of rats used in the operant conditioning procedure. COMPARISON WITH EXISTING METHODS AND CONCLUSIONS: A novel technique of operant conditioning adapted to infancy was developed by training animals to emit a particular response to gain access to alcohol solution as a reinforcer.

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According to the psychological literature, implicit motives allow for the characterization of behavior, subsequent success, and long-term development. Contrary to personality traits, implicit motives are often deemed to be rather stable personality characteristics. Normally, implicit motives are obtained by Operant Motives, unconscious intrinsic desires measured by the Operant Motive Test (OMT). The OMT test requires participants to write freely descriptions associated with a set of provided images and questions. In this work, we explore different recent machine learning techniques and various text representation techniques for facing the problem of the OMT classification task. We focused on advanced language representations (e.g, BERT, XLM, and DistilBERT) and deep Supervised Autoencoders for solving the OMT task. We performed an exhaustive analysis and compared their performance against fully connected neural networks and traditional support vector classifiers. Our comparative study highlights the importance of BERT which outperforms the traditional machine learning techniques by a relative improvement of 7.9%. In addition, we performed an analysis of how the BERT attention mechanism is being modified. Our findings indicate that the writing style features acquire higher importance at the moment of accurately identifying the different OMT categories. This is the first time that a study to determine the performance of different transformer-based architectures in the OMT task is performed. Similarly, our work propose, for the first time, using deep supervised autoencoders in the OMT classification task. Our experiments demonstrate that transformer-based methods exhibit the best empirical results, obtaining a relative improvement of 7.9% over the competitive baseline suggested as part of the GermEval 2020 challenge. Additionally, we show that features associated with the writing style are more important than content-based words. Some of these findings show strong connections to previously reported behavioral research on the implicit psychometrics theory.

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Emotional disturbances emerge following alcohol withdrawal. The anxiolytic effect of alcohol may be one important motivation for its consumption in conditions where alcohol intake is anxiety reducing. Besides, early alcohol experience will predict future alcohol-related problems at some point in their lives. Rats classified according to their anxiety-like behavior phenotype show a higher preference for alcohol. Yet, despite preclinical studies have identified the behavioral and physiological effects of alcohol withdrawal, little has been shown on relapse to alcohol after a period of abstinence following intermittent long-term alcohol consumption in low-(LA) and high-anxiety (HA) phenotype rats. This study attempts to assess the role of emotional reactivity of early-aged LA and HA rats on later alcohol preference, through an operant response procedure. For this, a sweetened liquid fading procedure associated with a long-term and intermittent voluntary alcohol drinking was used, with the animals being tested on different withdrawal periods. Alcohol withdrawal symptoms were recorded, and blood alcohol levels were assessed at two intervals to examine the influence of anxiety phenotype on blood alcohol clearance. Data from HA control and HA withdrawn rats show that emotionality selectively influences alcohol preference. Blood alcohol decay was faster in HA than in LA alcohol pretreated rats. HA rats showed an ascending curve of alcohol intake, exhibiting a high level of alcohol drinking on withdrawal and withdrawal symptoms. Moreover, HA alcohol experienced rats show a high frequency of lever-pressing response during extinction, associated with a facilitation of bar-pressing recovery trials, an indication of alcohol-seeking behavior.

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A major frontier in neuroscience is to find neural correlates of perception, learning, decision making, and a variety of other types of behavior. In the last decades, modern devices allow simultaneous recordings of different operant responses and the electrical activity of large neuronal populations. However, the commercially available instruments for studying operant conditioning are expensive, and the design of low-cost chambers has emerged as an appealing alternative to resource-limited laboratories engaged in animal behavior. In this article, we provide a full description of a platform that records the operant behavior and synchronizes it with the electrophysiological activity. The programming of this platform is open source, flexible, and adaptable to a wide range of operant conditioning tasks. We also show results of operant conditioning experiments with freely moving rats with simultaneous electrophysiological recordings.

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The debate in the literature on the science-practice interface suggests a diversity of opinions on how to link science and practice to improve conservation. Understanding this diversity is key to addressing unequal power relations, avoiding the consideration of only dominant views, and identifying strategies to link science and practice. In turn, linking science and practice should promote conservation decisions that are socially robust and scientifically informed. To identify and describe the viewpoints of scientists and decision makers on how the science-practice interface should work in order to improve conservation decisions, we interviewed Brazilian scientists (ecologists and conservation scientists, n = 11) and decision makers (n = 11). We used Q methodology and asked participants to rank their agreement with 48 statements on how the science-practice interface should work in order to improve conservation decisions. We used principal component analysis to identify shared viewpoints. The predominant viewpoint, shared by scientists and decision makers, was characterized by valuing the integration of scientific and strategic knowledge to address environmental problems. The second viewpoint, held mostly by decision makers, was distinguished by assigning great importance to science in the decision-making process and calling for problem-relevant research. The third viewpoint, shared only by scientists, was characterized by an unwillingness to collaborate and a perception of scientists as producers of knowledge that may help decision makers. Most participants agreed organizations should promote collaboration and that actors and knowledge from both science and practice are relevant. Disagreements concerned specific roles assigned to actors, willingness to collaborate, and organizational and institutional arrangements considered effective to link science and practice. Our results suggest there is ample room for collaborations and that impediments lie mainly in existing organizations and formal institutional arrangements rather than in negative attitudes between scientists and decision makers.

Formas de Pensar Compartidas en Brasil sobre la Interrelación Ciencia-Práctica en la Ecología y la Conservación Resumen El debate en la literatura sobre la interrelación ciencia-práctica sugiere una diversidad de opiniones sobre cómo conectar a la ciencia con la práctica para mejorar la conservación. La comprensión de esta diversidad es clave para tratar con las relaciones desiguales de poder, evitar la considerar únicamente de los puntos de vista dominantes, e identificar las estrategias para vincular a la ciencia con la práctica. En cambio, la vinculación entre la ciencia y la práctica debería promover las decisiones de conservación que son socialmente fuertes y científicamente informadas. Entrevistamos a científicos (ecólogos y conservadores, n = 11) y tomadores de decisiones (n = 11) en Brasil para identificar y describir los puntos de vista de los científicos y de quienes toman las decisiones sobre cómo la interrelación ciencia-práctica debería trabajar con tal de mejorar las decisiones de conservación. Usamos la metodología Q y les pedimos a los participantes que clasificaran su acuerdo con 48 declaraciones sobre cómo la interrelación ciencia-práctica debería trabajar para mejorar las decisiones de conservación. Utilizamos un análisis de componentes principales para identificar los puntos de vista compartidos. El punto de vista predominante, compartido entre los científicos y quienes toman las decisiones, se caracterizó por el valor que le dio a la integración del conocimiento científico y el estratégico para tratar los problemas ambientales. El segundo punto de vista, compartido por la mayoría de quienes toman las decisiones, se distinguió por asignarle una gran importancia a la ciencia en cuanto al proceso de toma de decisiones y a la petición de investigación relevante para los problemas. El tercer punto de vista, compartido sólo entre los científicos, se caracterizó por el rechazo a colaborar y por la percepción de los científicos como productores de conocimiento que puede ayudar a quienes toman las decisiones. La mayoría de los participantes estuvo de acuerdo en que las organizaciones deberían promover la colaboración y en que los actores y el conocimiento científico y práctico son relevantes. Los desacuerdos estuvieron relacionados con los roles específicos asignados a los actores, el deseo de colaborar, y los arreglos institucionales y de organización considerados como efectivos para vincular a la ciencia con la práctica. Nuestros resultados sugieren que existe suficiente espacio para las colaboraciones y que los impedimentos se deben principalmente a las organizaciones existentes y a los arreglos institucionales formales en lugar de a las actitudes negativas entre los científicos y quienes toman las decisiones.

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Introdução: O fator social interfere na realização de um transplante hepático, podendo contraindicá-lo momentaneamente. Para a análise e intervenção na realidade social do sujeito/paciente, o assistente social utiliza um instrumental que, devido ao seu valor, necessita de implementações, dado o movimento social. Objetivo: Adaptar o instrumental de avaliação social utilizado na Unidade de Transplante de Fígado. Método: Estudo quanti-qualitativo, pesquisa de campo com amostra intencional (assistentes sociais de Unidade de Transplante, com experiência no uso de instrumental de avaliação), análise de dados na perspectiva dialética e observação participante. Resultados: Todos os assistentes sociais utilizavam e três apontaram sugestões de melhorias, sendo os itens meios de comunicação e renda familiar os de maior destaque para alterações. As sugestões específicas para determinada unidade e as que alterariam o score do sistema de avaliação não foram implementadas. A partir da observação participante, outras alterações e informações foram incluídas para melhorar e ampliar o instrumental de acordo com a necessidade observada no cotidiano profissional. Conclusão: As alterações realizadas na adaptação favorecem a abordagem das variáveis sociais no momento da avaliação e contribui para o registro das intervenções sociais. Além disso, avança na visão totalitária do sujeito e da realidade social.

Introduction: The social factor interferes with the performance of a liver transplant and may contraindicate it momentarily. For the analysis and intervention in the social reality of the subject / patient, the social worker uses a tool that, due to its importance, needs implementations, due to the social movement. Objective: To adapt the social assessment tool used in the Liver Transplant Unit. Methods: Qualitative and quantitative approach study, field research with intentional sample (Transplant Unit social workers experienced in using assessment tools), data analysis was performed from a dialectical perspective and participant observation. Results: All social workers used it, and three pointed to suggestions for improvement, with media and household income being the most prominent items for change. Specific suggestions for a particular unit and those that would change the rating system score were not implemented. From participant observation, other changes and information were included to improve and expand the tool according to the need observed in the professional routine. Conclusion: Changes in adaptation favor the approach of social variables at the time of assessment and contribute to the registration of social interventions. Moreover, it advances in the totalitarian view of the subject and social reality.

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Impulsivity has traditionally been thought to involve various behavioral traits that can be measured using different laboratory protocols. Whereas some authors regard different measures of impulsivity as reflecting fundamentally distinct and unrelated behavioral tendencies (fragmentation approach), others regard those different indexes as analogue forms of the same behavioral tendency, only superficially different (unification approach). Unifying accounts range from mere intuitions to more sophisticated theoretical systems. Some of the more complete attempts at unifying are intriguing but have validity weaknesses. We propose a new unifying attempt based on theoretical points posed by other authors and supplemented by theory and research on associative learning. We then apply these assumptions to characterize the paradigms used to study impulsivity in laboratory settings and evaluate their scope as an attempt at unification. We argue that our approach possesses a good balance of parsimony and empirical and theoretical grounding, as well as a more encompassing scope, and is more suitable for experimental testing than previous theoretical frameworks. In addition, the proposed approach is capable of generating a new definition of impulsivity and outlines a hypothesis of how self-control can be developed. Finally, we examine the fragmentation approach from a different perspective, emphasizing the importance of finding similarities among seemingly different phenomena.

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Reinforcement omission effects (ROEs) are characterized by higher response rates after reinforcement omission than after reinforcement delivery. This pattern of behavior is interpreted in terms of motivational and attentional processes. Recent studies from our laboratory have shown that the amygdala, nucleus accumbens, and medial prefrontal cortex are involved in ROE modulation. Also, the literature has demonstrated a role of other areas such as substantia nigra pars compacta (SNc) and the ventral tegmental area (VTA) in processes related to surprising events, such as prediction error and presentation or omission of an event (exteroceptive stimulus and reinforcement). Since these structures send projections to areas related to ROE modulation such as the amygdala, nucleus accumbens, and prefrontal cortex, the objective of the present study was to determine whether the SNc and VTA also integrate the circuit involved in ROE modulation. Rats were trained on a fixed-interval 12 s with limited-hold 6 s signaled schedule of reinforcement (Pre-lesion training). After acquisition of stable performance, the rats received bilateral neurotoxic lesions of the SNc (Experiment 1) and VTA (Experiment 2). Following postoperative recovery, the rats were submitted to two refresher sessions (Post-lesion training). Subsequently, the training was changed from a 100 to a 50% schedule of reinforcement (Post-lesion testing). In both experiments, the results showed that there was no difference in performance between sham rats and rats with bilateral lesions of the SNc or the VTA.

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Even though innate behaviors are essential for assuring quick responses to expected stimuli, experience-dependent behavioral plasticity confers an advantage when unexpected conditions arise. As being rigidly responsive to too many stimuli can be biologically expensive, adapting preferences to time-dependent relevant environmental conditions provide a cheaper and wider behavioral reactivity. According to their specific life habits, animals prioritize different sensory modalities to maximize environment exploitation. Besides, when mediating learning processes, the salience of a stimulus usually plays a relevant role in determining the intensity of an association. Then, sensory prioritization might reflect an heterogeneity in the cognitive abilities of an individual. Here, we analyze in the kissing bug Rhodnius prolixus if stimuli from different sensory modalities generate different cognitive capacities under an operant aversive paradigm. In a 2-choice walking arena, by registering the spatial distribution of insects over an experimental arena, we evaluated firstly the innate responses of bugs confronted to mechanical (rough substrate), visual (green light), thermal (32°C heated plate), hygric (humidified substrate), gustatory (sodium chloride), and olfactory (isobutyric acid) stimuli. In further experimental series bugs were submitted to an aversive operant conditioning by pairing each stimulus with a negative reinforcement. Subsequent tests allowed us to analyze if the innate behaviors were modulated by such previous aversive experience. In our experimental setup mechanical and visual stimuli were neutral, the thermal cue was attractive, and the hygric, gustatory and olfactory ones were innately aversive. After the aversive conditioning, responses to the mechanical, the visual, the hygric and the gustatory stimuli were modulated while responses to the thermal and the olfactory stimuli remained rigid. We present evidences that the spatial learning capacities of R. prolixus are dependent on the sensory modality of the conditioned stimulus, regardless their innate valence (i.e., neutral, attractive, or aversive). These differences might be given by the biological relevance of the stimuli and/or by evolutionary aspects of the life traits of this hematophagous insect.

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Operant-conditioning boxes are widely used in animal training, allowing researchers to shape specific behaviors through reinforcements and/or punishments. Commercially available devices are expensive and run with proprietary software and hardware, hampering adaptations for the specific needs of an experiment. Therefore, many low-cost and open-source devices have recently been developed, but there are still few options for studying auditory behaviors. To overcome this problem, we developed a device based on a computer and an Arduino Mega 2560 board, named OBAT (Operant Box for Auditory Tasks), designed to present two different auditory stimuli to small primates. It has three modules: sound delivery, response bars, and reward system. We estimate that OBAT is at least 4-10 times cheaper than commercially available operant-conditioning boxes. Data from a behavioral pilot test ensured that the device can be used to train a marmoset in an auditory discrimination task. In addition, despite its low cost, accuracy tests showed that the OBAT operates with a high temporal precision. All schematics and software source code are available so that other groups can easily replicate the experiment or adapt the device to their own needs.

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Operant extinction is learning to supress a previously rewarded behavior. It is known to be strongly associated with the specific context in which it was acquired, which limits the therapeutic use of operant extinction in behavioral treatments, e.g., of addiction. We examined whether sleep influences contextual memory of operant extinction over time, using two different recall tests (Recent and Remote). Rats were trained in an operant conditioning task (lever press) in context A, then underwent extinction training in context B, followed by a 3-h retention period that contained either spontaneous morning sleep, morning sleep deprivation, or spontaneous evening wakefulness. A recall test was performed either immediately after the 3-h experimental retention period (Recent recall) or after 48 h (Remote), in the extinction context B and in a novel context C. The two main findings were: (i) at the Recent recall test, sleep in comparison with sleep deprivation and spontaneous wakefulness enhanced extinction memory but, only in the extinction context B; (ii) at the Remote recall, extinction performance after sleep was enhanced in both contexts B and C to an extent comparable to levels at Recent recall in context B. Interestingly, extinction performance at Remote recall was also improved in the sleep deprivation groups in both contexts, with no difference to performance in the sleep group. Our results suggest that 3 h of post-learning sleep transiently facilitate the context specificity of operant extinction at a Recent recall. However, the improvement and contextual generalization of operant extinction memory observed in the long-term, i.e., after 48 h, does not require immediate post-learning sleep.

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Prior studies indicate that neonates are very sensitive to ethanol's positive reinforcing effects and to its depressant effects upon breathing. Acetaldehyde (ACD) appears to play a major role in terms of modulating early reinforcing effects of the drug. Yet, there is no pre-existing literature relative to the incidence of this metabolite upon respiratory plasticity. The present study analyzed physiological and behavioral effects of early central administrations of ethanol, acetaldehyde or vehicle. Respiration rates (breaths/min) were registered at post-natal days (PDs) 2 and 4 (post-administration time: 5, 60, or 120 min). At PD5, all pups were placed in a context (plethysmograph) where they had previously experienced the effects of central administrations and breathing patterns were recorded. Following this test, pups were evaluated using and operant conditioning procedure where ethanol or saccharin served as positive reinforcers. Body temperatures were also registered prior to drug administrations as well as at the beginning and the end of each specific evaluation. Across days, breathing responses were high at the beginning of the evaluation session and progressively declined as a function of the passage of time. At PDs 2 and 4, shortly after central administration (5 min), ACD exerted a significant depression upon respiration frequencies. At PD5, non-intoxicated pups with a prior history of ACD central administrations, exhibited a marked increase in respiratory frequencies; a result that probably indicates a conditioned compensatory response. When operant testing procedures were conducted, prior ethanol or ACD central administrations were found to reduce the reinforcing effects of ethanol. This was not the case when saccharin was employed as a reinforcer. As a whole, the results indicate a significant role of central ACD upon respiratory plasticity of the neonate and upon ethanol's reinforcing effects; phenomena that affect the physiological integrity of the immature organism and its subsequent affinity for ethanol operationalized through self-administration procedures.

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The present study evaluated context-dependent learning under an operant conditioning procedure in infant rats. Preweanling rats were trained in context A during postnatal days (PDs) 16 and 17 to learn an appetitive operant conditioning task, employing milk chocolate as appetitive reinforcer. On PD18 the operant response was extinguished in context A, or in an alternative context B. The change from context A to B between acquisition and extinction did not affect the number of responses during extinction, but slightly modified the shape of the extinction curve. On PD19, a renewal test conducted in context A clearly showed ABA-renewal of the extinguished operant response. These results add to the body of evidence indicating that infants are able to acquire and retain contextual information, and support the notion that extinction during this ontogenetic period involves new learning.

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Impulsivity-related measures have been obtained using operantconditioning tasks. Although it has been suggested that impulsivity indices can also be obtained using the elevated plus-maze (EPM), an anxiety-related animal test, no studies have examined the relationship between anxiety-related variables in EPM and impulsivity-related indices obtained during operant conditioning. Correlations between EPM measures and performance in a 60-s fixed-interval schedule of reinforcement (FI 60-s) were established in this study. Seventeen female rats were exposed to the EPM before starting training in the FI 60-s schedule. A positive correlation was found between the percentage of time spent in the central area of the EPM and both the FI efficiency index and the inter-response times. In addition, these three measures were positively correlated within Factor 1 of a factor analysis. No correlations were observed between open-arms measures in EPM and operant performance. These results suggest that time in the central area of the EPM may be a useful index of impulsivity in rodents without a pre-determined trait of impulsivity.

Medidas relacionadas a impulsividad se han obtenido mediante tareas de condicionamiento operante. Aunque se ha sugerido que índices de impulsividad pueden ser también obtenidos usando el laberinto en cruz elevado (LCE), una prueba animal relacionada con ansiedad, ningún estudio ha examinado la relación entre las variables de ansiedad en el LCE e índices de impulsividad obtenidos durante condicionamiento operante. En este estudio se establecieron correlaciones entre medidas del LCE y el desempeño en un programa de reforzamiento de intervalo fijo 60-s (IF 60-s). Diecisiete ratas hembras fueron expuestas la LCE antes de iniciar el entrenamiento en el programa de IF 60-s. Se encontró una correlación positiva entre el porcentaje de tiempo de permanencia en el área central del LCE y tanto el índice de eficiencia como los tiempos entre respuestas en IF. Adicionalmente, estas tres medidas correlacionaron de forma positiva dentro del Factor 1 del análisis factorial. No se observaron correlaciones entre las medidas de los brazos abiertos del LCE y la ejecución operante. Los resultados sugieren que el tiempo en el área central del LCE podría ser un índice útil de impulsividad en roedores sin un perfil predeterminado de impulsividad.