Changes in dopamine transporter binding in nucleus accumbens following chronic self-administration cocaine: heroin combinations

Concurrent use of cocaine and heroin (speedball) has been shown to exert synergistic effects on dopamine neurotransmission in the nucleus accumbens (NAc), as observed by significant increases in extracellular dopamine levels and compensatory elevations in the maximal reuptake rate of dopamine. The present studies were undertaken to determine whether chronic self-administration of cocaine, heroin or a combination of cocaine:heroin led to compensatory changes in the abundance and/or affinity of high- and low-affinity DAT binding sites. Saturation binding of the cocaine analog [(125) I] 3β-(4-iodophenyl)tropan-2β-carboxylic acid methyl ester ([(125) I]RTI-55) in rat NAc membranes resulted in binding curves that were best fit to two-site binding models, allowing calculation of dissociation constant (Kd ) and binding density (Bmax ) values corresponding to high- and low-affinity DAT binding sites. Scatchard analysis of the saturation binding curves clearly demonstrate the presence of high- and low- affinity binding sites in the NAc, with low-affinity sites comprising 85 to 94% of the binding sites. DAT binding analyses revealed that self-administration of cocaine and a cocaine:heroin combination increased the affinity of the low-affinity site for the cocaine congener RTI-55 compared to saline. These results indicate that the alterations observed following chronic speedball self-administration are likely due to the cocaine component alone; thus further studies are necessary to elaborate upon the synergistic effect of cocaine:heroin combinations on the dopamine system in the NAc.

Sex chromosome complement influences operant responding for a palatable food in mice

The procurement and consumption of palatable, calorie-dense foods is influenced by the nutritional and hedonic value of foods. Although many factors can influence the control over behavior by foods rich in sugar and fat, emerging evidence indicates that biological sex may play a particularly crucial role in the types of foods individuals seek out, as well as the level of motivation individuals will exert to obtain those foods. However, a systematic investigation of food-seeking and consumption that disentangles the effects of the major sex-biasing factors, including sex chromosome complement and organizational and activational effects of sex hormones, has yet to be conducted. Using the four core genotypes mouse model system, we separated and quantified the effects of sex chromosome complement and gonadal sex on consumption of and motivation to obtain a highly palatable solution [sweetened condensed milk (SCM)]. Gonadectomized mice with an XY sex chromosome complement, compared with those with two X chromosomes, independent of gonadal sex, appeared to be more sensitive to the reward value of the SCM solution and were more motivated to expend effort to obtain it, as evidenced by their dramatically greater expended effort in an instrumental task with progressively larger response-to-reward ratios. Gonadal sex independently affected free consumption of the solution but not motivation to obtain it. These data indicate that gonadal and chromosomal sex effects independently influence reward-related behaviors, contributing to sexually dimorphic patterns of behavior related to the pursuit and consumption of rewards.

Operant conditioning of synaptic and spiking activity patterns in single hippocampal neurons

Learning is a process of plastic adaptation through which a neural circuit generates a more preferable outcome; however, at a microscopic level, little is known about how synaptic activity is patterned into a desired configuration. Here, we report that animals can generate a specific form of synaptic activity in a given neuron in the hippocampus. In awake, head-restricted mice, we applied electrical stimulation to the lateral hypothalamus, a reward-associated brain region, when whole-cell patch-clamped CA1 neurons exhibited spontaneous synaptic activity that met preset criteria. Within 15 min, the mice learned to generate frequently the excitatory synaptic input pattern that satisfied the criteria. This reinforcement learning of synaptic activity was not observed for inhibitory input patterns. When a burst unit activity pattern was conditioned in paired and nonpaired paradigms, the frequency of burst-spiking events increased and decreased, respectively. The burst reinforcement occurred in the conditioned neuron but not in other adjacent neurons; however, ripple field oscillations were concomitantly reinforced. Neural conditioning depended on activation of NMDA receptors and dopamine D1 receptors. Acutely stressed mice and depression model mice that were subjected to forced swimming failed to exhibit the neural conditioning. This learning deficit was rescued by repetitive treatment with fluoxetine, an antidepressant. Therefore, internally motivated animals are capable of routing an ongoing action potential series into a specific neural pathway of the hippocampal network.

Reward and reinforcement activity in the nucleus accumbens during learning

The nucleus accumbens core (NAcc) has been implicated in learning associations between sensory cues and profitable motor responses. However, the precise mechanisms that underlie these functions remain unclear. We recorded single-neuron activity from the NAcc of primates trained to perform a visual-motor associative learning task. During learning, we found two distinct classes of NAcc neurons. The first class demonstrated progressive increases in firing rates at the go-cue, feedback/tone and reward epochs of the task, as novel associations were learned. This suggests that these neurons may play a role in the exploitation of rewarding behaviors. In contrast, the second class exhibited attenuated firing rates, but only at the reward epoch of the task. These findings suggest that some NAcc neurons play a role in reward-based reinforcement during learning.

Firing pattern characteristics of tonically active neurons in rat striatum: context dependent or species divergent?

Tonically active neurons (TANs)--presumably, striatal cholinergic interneurons--exert a strong influence on striatal information processing. Primate studies often describe a characteristic TAN response comprising suppressed activity followed by rebound firing that occasionally is preceded by a brief activation. By contrast, studies in behaving rats report pronounced excitation during movement. These differences in firing patterns may be due to variations in behavioral conditions or could stem from the fact that TANs in rodents use different neuronal mechanisms. If similar/different task conditions yield similar/different activity patterns, then the two species may share neuronal mechanisms; however, if similar task conditions yield different activity patterns, then the two species use different neuronal mechanisms. To evaluate these possibilities, we recorded TAN activity in the ventral and dorsolateral striatal regions in rats performing a simple instrumental task similar in concept to one used in primate studies. We demonstrate that TAN activity is substantially influenced by event context; yet, under identical task conditions, primate and rat TANs display similar activity patterns, whereas under different conditions they do not. Our results suggest that the observed differences in firing patterns likely reflect dissimilarities in task attributes rather than species-dependent neuronal mechanisms and call for re-evaluation of the excitatory response in primate research.

Nicotine and methamphetamine disrupt habituation of sensory reinforcer effectiveness in male rats

The reinforcing effectiveness of a sensory stimulus such as light-onset rapidly habituates (Lloyd, Gancarz, Ashrafioun, Kausch, & Richards, 2012). According to memory-based theories, habituation occurs if a memory exists for perceived stimulation, and dishabituation occurs if a memory does not exist and the stimulation is "unexpected." According to Redgrave and Gurney (2006), unexpected response-contingent sensory stimuli increase phasic firing of dopamine neurons, providing a sensory error signal that reflects the difference between perceived and expected stimuli. Together, memory-based theories of habituation and the sensory error signal hypothesis predict a disruption (slowing) of habituation rate by novel response-contingent sensory stimulation or by artificial increases in dopamine neurotransmission by stimulant drugs. To test these predictions, we examined the effects of stimulant drugs on both the operant level of responding (snout-poking) and operant responding for a sensory reinforcer (light-onset) presented according to a fixed ratio 1 schedule. Robust within-session decreases in responding indicating habituation were observed. The effects of stimulant drugs (saline, n = 10; nicotine, 0.40 mg/kg, n = 10; and methamphetamine, 0.75 mg/kg, n = 9) on habituation in rats were determined. Nicotine was found to decrease habituation rate and did not affect response rate, while methamphetamine decreased habituation rate and increased response rate. In addition, introduction of a novel visual stimulus reinforcer decreased habituation rate and increased responding. These findings show that habituation of reinforcer effectiveness modulates operant responding for sensory reinforcers, and that stimulant drugs may disrupt normally occurring habituation of reinforcer effectiveness by increasing dopamine neurotransmission.

Sustaining a "culture of silence" in the neonatal intensive care unit during nonemergency situations: a grounded theory on ensuring adherence to behavioral modification to reduce noise levels

The aim of this study was to generate a substantive theory explaining how the staff in a resource-limited neonatal intensive care unit (NICU) of a developing nation manage to ensure adherence to behavioral modification components of a noise reduction protocol (NsRP) during nonemergency situations. The study was conducted after implementation of an NsRP in a level III NICU of south India. The normal routine of the NICU is highly dynamic because of various categories of staff conducting clinical rounds followed by care-giving activities. This is unpredictably interspersed with very noisy emergency management of neonates who suddenly fall sick. In-depth interviews were conducted with 36 staff members of the NICU (20 staff nurses, six nursing aides, and 10 physicians). Group discussions were conducted with 20 staff nurses and six nursing aides. Data analysis was done in line with the reformulated grounded theory approach, which was based on inductive examination of textual information. The results of the analysis showed that the main concern was to ensure adherence to behavioral modification components of the NsRP. This was addressed by using strategies to “sustain a culture of silence in NICU during nonemergency situations” (core category). The main strategies employed were building awareness momentum, causing awareness percolation, developing a sense of ownership, expansion of caring practices, evolution of adherence, and displaying performance indicators. The “culture of silence” reconditions the existing staff and conditions new staff members joining the NICU. During emergency situations, a “noisy culture” prevailed because of pragmatic neglect of behavioral modification when life support overrode all other concerns. In addition to this, the process of operant conditioning should be formally conducted once every 18 months. The results of this study may be adapted to create similar strategies and establish context specific NsRPs in NICUs with resource constraints.

A pacifier-activated music player with mother's voice improves oral feeding in preterm infants

OBJECTIVES

We conducted a randomized trial to test the hypothesis that mother's voice played through a pacifier-activated music player (PAM) during nonnutritive sucking would improve the development of sucking ability and promote more effective oral feeding in preterm infants.

METHODS

Preterm infants between 34 0/7 and 35 6/7 weeks' postmenstrual age, including those with brain injury, who were taking at least half their feedings enterally and less than half orally, were randomly assigned to receive 5 daily 15-minute sessions of either PAM with mother's recorded voice or no PAM, along with routine nonnutritive sucking and maternal care in both groups. Assignment was masked to the clinical team.

RESULTS

Ninety-four infants (46 and 48 in the PAM intervention and control groups, respectively) completed the study. The intervention group had significantly increased oral feeding rate (2.0 vs. 0.9 mL/min, P < .001), oral volume intake (91.1 vs. 48.1 mL/kg/d, P = .001), oral feeds/day (6.5 vs. 4.0, P < .001), and faster time-to-full oral feedings (31 vs. 38 d, P = .04) compared with controls. Weight gain and cortisol levels during the 5-day protocol were not different between groups. Average hospital stays were 20% shorter in the PAM group, but the difference was not significant (P = .07).

CONCLUSIONS

A PAM using mother's voice improves oral feeding skills in preterm infants without adverse effects on hormonal stress or growth.

Dogs' Body Language Relevant to Learning Achievement

Simple Summary

For humans and dogs to live together amiably, dog training is required, and a lack of obedience training is significantly related to the prevalence of certain behavioral problems. To train efficiently, it is important that the trainer/owner ascertains the learning level of the dog. Understanding the dog’s body language helps humans understand the animal’s emotions. This study evaluated the posture of certain dog body parts during operant conditioning. Our findings suggest that certain postures were related to the dog’s learning level during operant conditioning. Being aware of these postures could be helpful to understand canine emotion during learning.

Abstract

The facial expressions and body postures of dogs can give helpful information about their moods and emotional states. People can more effectively obedience train their dogs if we can identify the mannerisms associated with learning in dogs. The aim of this study was to clarify the dog’s body language during operant conditioning to predict achievement in the test that followed by measuring the duration of behaviors. Forty-six untrained dogs (17 males and 26 females) of various breeds were used. Each session consisted of 5 minutes of training with a treat reward followed by 3 minutes of rest and finally an operant conditioning test that consisted of 20 “hand motion” cues. The operant tests were conducted a total of nine times over three consecutive days, and the success numbers were counted. The duration of the dog’s behavior, focusing on the dog’s eyes, mouth, ears, tail and tail-wagging, was recorded during the operant conditioning sessions before the test. Particular behaviors, including wide-eyes, closed mouth, erect ears, and forward and high tail carriage, without wagging or with short and quick wagging, related to high achievement results. It is concluded that dogs' body language during operant conditioning was related to their success rate.

Effects of management strategies on glucocorticoids and behavior in Indian rhinoceros (Rhinoceros unicornis): translocation and operant conditioning

The ex situ Indian rhino population experienced a decrease in genetic diversity indicating that the breeding program could possibly benefit from novel reproductive management strategies to ensure population sustainability. We sought to determine how management tools used for reproductive management, specifically translocation and operant conditioning, impact physiological and behavioral measures of welfare in Indian rhinos. First, an adrenocorticotropic hormone challenge performed in an adult male resulted in a 38-fold increase in urinary and a 3.5-fold increase in fecal glucocorticoid metabolites (FGM). Mean and peak FGM differed among three females, but all demonstrated elevated (P < 0.0001) concentrations for variable durations after translocation that lasted up to 9 weeks. Lastly, behavioral and adrenal responses of two females to operant conditioning to stand during transrectal ultrasound exams were monitored and rhinos differed in their mean and peak FGM concentrations. However, FGM were not different before versus during training or on pasture versus in the barn. One female exhibited more stereotypic behavior during training in the barn than on pasture (P < 0.05); although, stereotypies (1.73% of time) were relatively uncommon overall. In summary, individual variation exists in FGM both at baseline levels and in response to a stressor. In addition, while a transient rise in glucocorticoid activity post-translocation indicated that Indian rhinos have a physiological response to changes in their environment, minor alterations in daily routines using operant conditioning only resulted in minimal changes in behaviors and FGM.

Volitional enhancement of firing synchrony and oscillation by neuronal operant conditioning: interaction with neurorehabilitation and brain-machine interface

In this review, we focus on neuronal operant conditioning in which increments in neuronal activities are directly rewarded without behaviors. We discuss the potential of this approach to elucidate neuronal plasticity for enhancing specific brain functions and its interaction with the progress in neurorehabilitation and brain-machine interfaces. The key to-be-conditioned activities that this paper emphasizes are synchronous and oscillatory firings of multiple neurons that reflect activities of cell assemblies. First, we introduce certain well-known studies on neuronal operant conditioning in which conditioned enhancements of neuronal firing were reported in animals and humans. These studies demonstrated the feasibility of volitional control over neuronal activity. Second, we refer to the recent studies on operant conditioning of synchrony and oscillation of neuronal activities. In particular, we introduce a recent study showing volitional enhancement of oscillatory activity in monkey motor cortex and our study showing selective enhancement of firing synchrony of neighboring neurons in rat hippocampus. Third, we discuss the reasons for emphasizing firing synchrony and oscillation in neuronal operant conditioning, the main reason being that they reflect the activities of cell assemblies, which have been suggested to be basic neuronal codes representing information in the brain. Finally, we discuss the interaction of neuronal operant conditioning with neurorehabilitation and brain-machine interface (BMI). We argue that synchrony and oscillation of neuronal firing are the key activities required for developing both reliable neurorehabilitation and high-performance BMI. Further, we conclude that research of neuronal operant conditioning, neurorehabilitation, BMI, and system neuroscience will produce findings applicable to these interrelated fields, and neuronal synchrony and oscillation can be a common important bridge among all of them.

Habituation of reinforcer effectiveness

In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral- and neural-based explanations of reinforcement. We argue that HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009; Rankin etal., 2009). We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow) normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect “accelerated-HRE.” Consideration of HRE is important for the development of effective reinforcement-based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

Locomotor impact of beneficial or nonbeneficial H-reflex conditioning after spinal cord injury

When new motor learning changes neurons and synapses in the spinal cord, it may affect previously learned behaviors that depend on the same spinal neurons and synapses. To explore these effects, we used operant conditioning to strengthen or weaken the right soleus H-reflex pathway in rats in which a right spinal cord contusion had impaired locomotion. When up-conditioning increased the H-reflex, locomotion improved. Steps became longer, and step-cycle asymmetry (i.e., limping) disappeared. In contrast, when down-conditioning decreased the H-reflex, locomotion did not worsen. Steps did not become shorter, and asymmetry did not increase. Electromyographic and kinematic analyses explained how H-reflex increase improved locomotion and why H-reflex decrease did not further impair it. Although the impact of up-conditioning or down-conditioning on the H-reflex pathway was still present during locomotion, only up-conditioning affected the soleus locomotor burst. Additionally, compensatory plasticity apparently prevented the weaker H-reflex pathway caused by down-conditioning from weakening the locomotor burst and further impairing locomotion. The results support the hypothesis that the state of the spinal cord is a "negotiated equilibrium" that serves all the behaviors that depend on it. When new learning changes the spinal cord, old behaviors undergo concurrent relearning that preserves or improves their key features. Thus, if an old behavior has been impaired by trauma or disease, spinal reflex conditioning, by changing a specific pathway and triggering a new negotiation, may enable recovery beyond that achieved simply by practicing the old behavior. Spinal reflex conditioning protocols might complement other neurorehabilitation methods and enhance recovery.

Food rewards modulate the activity of song neurons in Bengalese finches

Vocal learning, a critical component of speech acquisition, is a rare trait in animals. Songbirds are a well-established animal model in vocal learning research; male birds acquire novel vocal patterns and have a well-developed 'song system' in the brain. Although this system is unique to songbirds, anatomical and physiological studies have reported similarities between the song system and the thalamo-cortico-basal ganglia circuit that is conserved among reptiles, birds, and mammals. Here, we focused on the similarity of the neural response between these two systems while animals were engaging in operant tasks. Neurons in the basal ganglia of vertebrates are activated in response to food rewards and reward predictions in behavioral tasks. A striatal nucleus in the avian song system, Area X, is necessary for vocal learning and is considered specialized for singing. We found that the spiking activity of singing-related Area X neurons was modulated by food rewards and reward signals in an operant task. As previous studies showed that Area X is not critical for general cognitive tasks, the role of Area X in general learning might be limited and vestigial. However, our results provide a new viewpoint to investigate the independence of the vocal learning system from neural systems involved in other cognitive tasks.

Effects of a novel CB1 agonist on visual attention in male rats: role of strategy and expectancy in task accuracy

The effects of cannabinoid CB1 agonists (including Δ9-tetrahydrocannabinol, the main psychoactive component of marijuana) on attention are uncertain, with reports of impairments, no effects, and occasionally performance enhancements. To better understand these effects, we sought to uncover a role of changing online (within-session) strategy as a possible mediator of the effects of the novel, potent CB1 agonist AM 4054, on a model of sustained attention in male Sprague-Dawley rats. In this operant, two-choice reaction time (RT) task, AM 4054 decreased accuracy in an asymmetric manner; that is, performance was spared on one lever but impaired on the other. Furthermore, this pattern was enhanced by the outcome of the previous trial such that AM 4054 strengthened a win-stay strategy on the "preferred" lever and a lose-shift strategy on the "nonpreferred" lever. This pattern is often found in tests of expectancy; therefore, in a second experiment AM 4054 enhanced expectancy that we engendered by altering the probability of the two stimulus cues. Accuracy was impaired in reporting the less frequent cue, but only after two or more presentations of the more frequent cue. Taking the results of the experiments together, AM 4054 engendered expectancy by increasing the role of previous trial location and outcome on performance of future trials, diminishing stimulus control (and therefore, accuracy). This novel effect of CB1 receptor agonism may contribute to the deleterious effects of cannabinoids on attention.

Real-time fMRI neurofeedback: progress and challenges

In February of 2012, the first international conference on real time functional magnetic resonance imaging (rtfMRI) neurofeedback was held at the Swiss Federal Institute of Technology Zurich (ETHZ), Switzerland. This review summarizes progress in the field, introduces current debates, elucidates open questions, and offers viewpoints derived from the conference. The review offers perspectives on study design, scientific and clinical applications, rtfMRI learning mechanisms and future outlook.

Songbirds and humans apply different strategies in a sound sequence discrimination task

The abilities of animals and humans to extract rules from sound sequences have previously been compared using observation of spontaneous responses and conditioning techniques. However, the results were inconsistently interpreted across studies possibly due to methodological and/or species differences. Therefore, we examined the strategies for discrimination of sound sequences in Bengalese finches and humans using the same protocol. Birds were trained on a GO/NOGO task to discriminate between two categories of sound stimulus generated based on an "AAB" or "ABB" rule. The sound elements used were taken from a variety of male (M) and female (F) calls, such that the sequences could be represented as MMF and MFF. In test sessions, FFM and FMM sequences, which were never presented in the training sessions but conformed to the rule, were presented as probe stimuli. The results suggested two discriminative strategies were being applied: (1) memorizing sound patterns of either GO or NOGO stimuli and generating the appropriate responses for only those sounds; and (2) using the repeated element as a cue. There was no evidence that the birds successfully extracted the abstract rule (i.e., AAB and ABB); MMF-GO subjects did not produce a GO response for FFM and vice versa. Next we examined whether those strategies were also applicable for human participants on the same task. The results and questionnaires revealed that participants extracted the abstract rule, and most of them employed it to discriminate the sequences. This strategy was never observed in bird subjects, although some participants used strategies similar to the birds when responding to the probe stimuli. Our results showed that the human participants applied the abstract rule in the task even without instruction but Bengalese finches did not, thereby reconfirming that humans have to extract abstract rules from sound sequences that is distinct from non-human animals.

Craving to quit: psychological models and neurobiological mechanisms of mindfulness training as treatment for addictions

Humans suffer heavily from substance use disorders and other addictions. Despite much effort that has been put into understanding the mechanisms of the addictive process, treatment strategies have remained suboptimal over the past several decades. Mindfulness training, which is based on ancient Buddhist models of human suffering, has recently shown preliminary efficacy in treating addictions. These early models show remarkable similarity to current models of the addictive process, especially in their overlap with operant conditioning (positive and negative reinforcement). Further, they may provide explanatory power for the mechanisms of mindfulness training, including its effects on core addictive elements, such as craving, and the underlying neurobiological processes that may be active therein. In this review, using smoking as an example, we will highlight similarities between ancient and modern views of the addictive process, review studies of mindfulness training for addictions and their effects on craving and other components of this process, and discuss recent neuroimaging findings that may inform our understanding of the neural mechanisms of mindfulness training.

Stimulus specificity and dishabituation of operant responding in humans

Habituation has recently been addressed within the operant conditioning paradigm. While the literature on this topic is growing, the examination of dishabituation, a fundamental characteristic of habituation, remains limited. This study expanded research on habituation of operant responding in non-human animals to research involving humans. Specifically, dishabituation and stimulus specificity were examined under a variety of conditions involving changes in the reinforcer type, reinforcement schedule, reinforcer amount, and selected properties of the antecedent stimuli for a computerized task with 46 undergraduate students. An additional 3 participants were exposed to a control condition. Evaluation of within session patterns of responding indicates that the introduction of stimulus changes into the operant context reliably produced dishabituation of operant responding in humans.

Altitude acclimatization improves submaximal cognitive performance in mice and involves an imbalance of the cholinergic system

The aim of this work was to reveal a hypothetical improvement of cognitive abilities in animals acclimatized to altitude and performing under ground level conditions, when looking at submaximal performance, once seen that it was not possible when looking at maximal scores. We modified contrasted cognitive tasks (object recognition, operant conditioning, eight-arm radial maze, and classical conditioning of the eyeblink reflex), increasing their complexity in an attempt to find performance differences in acclimatized animals vs. untrained controls. In addition, we studied, through immunohistochemical quantification, the expression of choline acetyltransferase and acetyl cholinesterase, enzymes involved in the synthesis and degradation of acetylcholine, in the septal area, piriform and visual cortexes, and the hippocampal CA1 area of animals submitted to acute hypobaric hypoxia, or acclimatized to this simulated altitude, to find a relationship between the cholinergic system and a cognitive improvement due to altitude acclimatization. Results showed subtle improvements of the cognitive capabilities of acclimatized animals in all of the tasks when performed under ground-level conditions (although not before 24 h), in the three tasks used to test explicit memory (object recognition, operant conditioning in the Skinner box, and eight-arm radial maze) and (from the first conditioning session) in the classical conditioning task used to evaluate implicit memory. An imbalance of choline acetyltransferase/acetyl cholinesterase expression was found in acclimatized animals, mainly 24 h after the acclimatization period. In conclusion, altitude acclimatization improves cognitive capabilities, in a process parallel to an imbalance of the cholinergic system.

Conceptualising the Impact of Arousal and Affective State on Training Outcomes of Operant Conditioning

Simple Summary

This article discusses the impacts of arousal and emotional state on training animals using methods based on reward and punishment. Three-dimensional graphs are provided to offer a visual means to illustrate how arousal and emotional state may influence the effectiveness of reward and punishment depending on the behaviour being trained. Dogs and horses are used to illustrate this with reference to commonly trained behaviours in a predatory and a prey animal.

Abstract

Animal training relies heavily on an understanding of species-specific behaviour as it integrates with operant conditioning principles. Following on from recent studies showing that affective states and arousal levels may correlate with behavioural outcomes, we explore the contribution of both affective state and arousal in behavioural responses to operant conditioning. This paper provides a framework for assessing how affective state and arousal may influence the efficacy of operant training methods. It provides a series of three-dimensional conceptual graphs as exemplars to describing putative influences of both affective state and arousal on the likelihood of dogs and horses performing commonly desired behaviours. These graphs are referred to as response landscapes, and they highlight the flexibility available for improving training efficacy and the likely need for different approaches to suit animals in different affective states and at various levels of arousal. Knowledge gaps are discussed and suggestions made for bridging them.

Impairment in long-term memory formation and learning-dependent synaptic plasticity in mice lacking glycogen synthase in the brain

Glycogen is the only carbohydrate reserve of the brain, but its overall contribution to brain functions remains unclear. Although it has traditionally been considered as an emergency energetic reservoir, increasing evidence points to a role of glycogen in the normal activity of the brain. To address this long-standing question, we generated a brain-specific Glycogen Synthase knockout (GYS1(Nestin-KO)) mouse and studied the functional consequences of the lack of glycogen in the brain under alert behaving conditions. These animals showed a significant deficiency in the acquisition of an associative learning task and in the concomitant activity-dependent changes in hippocampal synaptic strength. Long-term potentiation (LTP) evoked in the hippocampal CA3-CA1 synapse was also decreased in behaving GYS1(Nestin-KO) mice. These results unequivocally show a key role of brain glycogen in the proper acquisition of new motor and cognitive abilities and in the underlying changes in synaptic strength.

Why is it so hard to pay attention, or is it? Mindfulness, the factors of awakening and reward-based learning

Though relatively new to Western psychological and spiritual cultures, mindfulness training is becoming more widespread in the general public and is beginning to show promise therapeutically for maladies ranging from generalized stress to specific addictions. However, difficulties remain both with individuals being able to learn core concepts and techniques, such as concentration meditation, and more broadly, with treatment interventions not being optimized to helping individuals learn these. In this manuscript, we examine possible contributing factors to these difficulties. We bring together what is known scientifically about basic learning processes such as operant conditioning with some inspirational suggestions drawn from the early Buddhist dialogues collected in the Theravada Buddhist cannon, in particular the description of seven psychological factors known as "the factors of awakening". Bringing together scientific and textual suggestions, we give an overview of how primary operant conditioning processes lead to stress, and importantly, how a minor shift in emphasis in providing mindfulness training may indeed co-opt these very processes for the reduction and cessation of stress and suffering. Finally, we provide suggestions as to how these can be tracked individually and clinically over time.

Sensory reinforcement as a predictor of cocaine and water self-administration in rats

RATIONALE

The ability of locomotor activity in a novel environment (Loco) and visual stimulus reinforcement (VSR) to predict acquisition of responding for cocaine and water reinforcers in the absence of explicit audiovisual signals was evaluated.

METHODS

In Experiment 1 (Exp 1), rats (n = 60) were tested for VSR, followed by Loco, and finally acquisition of responding for cocaine (0.3 mg/kg/inf). In Experiment 2 (Exp 2), rats (n = 32) were tested for VSR, followed by Loco, and finally acquisition of responding for water (0.01 mL/reinforcer).

RESULTS

There were three main findings. First, Loco and VSR were significantly associated (Exp 1: r = 0.49, p < 0.00; Exp 2: r = 0.35, p < 0.05). Second, neither Loco (r = .00, p = 0.998) nor VSR (r = -0.12, p = 0.352) predicted acquisition of cocaine SA. Third, in the subgroup of animals that acquired cocaine SA, VSR (r = 0.41, p < 0.01) but not Loco (r = 0.28, p = 0.10) was positively associated with operant responding for cocaine. Both Loco and VSR (Loco: r = 0.37, p < 0.04; VSR: r = 0.51, p < 0.00) were positively associated with operant responding for water reinforcers.

CONCLUSIONS

The results indicate that VSR is at least as good a predictor of cocaine reinforced responding as Loco. VSR was predictive of operant responding for both drug and water reinforcers, while Loco was found to be predictive of responding only for water reinforcers. In studies that present visual stimuli in association with drug delivery, Loco may be predicting acquisition of responding for VSR rather than drug.

Effects of novelty and methamphetamine on conditioned and sensory reinforcement

BACKGROUND

Light onset can be both a sensory reinforcer (SR) with intrinsic reinforcing properties, and a conditioned reinforcer (CR) which predicts a biologically important reinforcer. Stimulant drugs, such as methamphetamine (METH), may increase the reinforcing effectiveness of CRs by enhancing the predictive properties of the CR. In contrast, METH-induced increases in the reinforcing effectiveness of SRs, are mediated by the immediate sensory consequences of the light.

METHODS

The effects of novelty (on SRs) and METH (on both CRs and SRs) were tested. Experiment 1: rats were pre-exposed to 5 s light and water pairings presented according to a variable-time (VT) 2 min schedule or unpaired water and light presented according to independent, concurrent VT 2 min schedules. Experiment 2: rats were pre-exposed to 5 s light presented according to a VT 2 min schedule, or no stimuli. In both experiments, the pre-exposure phase was followed by a test phase in which 5 s light onset was made response-contingent on a variable-interval (VI) 2 min schedule and the effects of METH (0.5 mg/kg) were determined.

RESULTS

Novel light onset was a more effective reinforcer than familiar light onset. METH increased the absolute rate of responding without increasing the relative frequency of responding for both CRs and SRs.

CONCLUSION

Novelty plays a role in determining the reinforcing effectiveness of SRs. The results are consistent with the interpretation that METH-induced increases in reinforcer effectiveness of CRs and SRs may be mediated by immediate sensory consequences, rather than prediction.