Acute and chronic effects of cocaine on the spontaneous behavior of pigeons

The present experiment examined the effects of acute and daily cocaine on spontaneous behavior patterns of pigeons. After determining the acute effects of a range of doses, 9 pigeons were divided into three groups that received one of three doses of cocaine daily, either 1.0, 3.0, or 10.0 mg/kg cocaine. Measures were taken of spontaneous locomotion, pecking, preening, and emesis. Under daily administration, cocaine induced consistent and substantial enhancements of its locomotor effects in all 9 pigeons, consistent with the phenomenon of locomotor sensitization. The maximum locomotor output did not differ according to the size of the daily dose. Locomotion was not elevated following tests of the saline vehicle, suggesting the effect was due to cocaine, not to a change in baseline or reactivity to the injection procedure. Cocaine dose‐dependently decreased preening when given acutely, and those effects were not altered by repeated cocaine administration. Pecking occurred at very low rates and was unresponsive to cocaine treatment. Cocaine‐induced emesis showed a dose‐dependent increase under initial tests with cocaine, and those effects were attenuated following daily exposure. In a final condition, cocaine was replaced with daily saline for 30 days to assess the persistence cocaine‐related increases in locomotion. Approximately half of the pigeons continued to show enhanced effects even after 30 days without cocaine, so although persistence was obtained, it showed marked intersubject variability. The data indicate that the effects of repeated cocaine administration on the behavior of pigeons shows parallels with many effects commonly reported with rodents (i.e., increased locomotion following repeated treatment, decrease in preening or grooming, persistence following drug withdrawal).     

Criticisms of the satiety hypothesis as an explanation for within-session decreases in responding

The authors of four papers recently reported that satiation provides a better explanation than habituation for within-session decreases in conditioned responding. Several arguments question this conclusion. First, the contribution of habituation to within-session changes in responding seems clearly established. Information that is consistent with habituation, but that is difficult to reconcile with satiation, is not adequately addressed. Second, the limited evidence offered in support of satiation is ambiguous because the results are just as compatible with habituation as with other satiety variables. Finally, the term satiation is used in an intuitive way that is sometimes contradicted by research about the termination of ingestion. Use of the technical term satiation in a way that differs from its conventional usage will only isolate operant psychology from other areas of psychological research.     

Brain asymmetry and autonomic conditioning: Sensitization control

In the present experiment we report effects of cerebral asymmetry, or laterality, during classical conditioning to facial emotional stimuli. Twenty-five female subjects were presented with slides of a happy face in one visual half-field (VHF), and simultaneously a slide of an angry face in the other VHF, followed by shock as the unconditioned stimulus (UCS). To control for effects of sensitization, a new stimulus, never associated with the UCS, was introduced in the extinction phase. Dependent measures were phasic heart rate responses (HR) and skin conductance responses (SCR). The HR results showed a significant right hemisphere effect for the CS-UCS association, that was not attributable to UCS sensitization. No significant effects were found for the SCRs. The basic HR finding was a right hemisphere superiority for learning of a conditioned association.     

Depression and stressful environments: identifying gaps in conceptualization and measurement

Background and Objectives: Stress is well known as a trigger of depressive reactions, fear, anxiety, and behavioral disorders. However, there are many gaps in the conceptualization and measurement of environmental stress. Results: Exciting developments in the neuroscience of stress have increasingly expanded our knowledge of mechanisms by which stress may affect emotional and behavioral adjustment. Ironically, environmental stress has often been a silent player in human studies of stress processes. There is a significant need for increased efforts to include environmental stress variables in models of internalizing and other disorders. Measurement and conceptualization issues are prominent, and this article makes the case for improved methods of measuring acute, chronic, and early life stress, and for additional conceptualization of the dynamically changing and bidirectional effects of stress on disorder over time. Conclusions: There is a critical need for greater focus on and better measurement of the environment and its impact on emotional and other disorders, with emphasis on developmentally informed hypotheses. Empirical findings and new perspectives may contribute enormously to our understanding of normal and abnormal outcomes, and also to the challenge of effective interventions to promote mental health and optimal functioning.     

Habituation To The Reinforcer May Contribute To Multiple-schedule Behavioral Contrast

Habituation to the reinforcer may contribute to multiple-schedule behavioral contrast. According to this argument, reducing reinforcers in one component of a multiple schedule reduces habituation to the reinforcer. Reducing habituation enhances the value, or effectiveness, of the remaining reinforcers, producing positive contrast. Enriching the reinforcers in one component increases habituation to that reinforcer. Increasing habituation decreases the effectiveness of the reinforcer, producing negative contrast. Such an idea is simple and parsimonious. It is not contradicted by any well-established finding in the contrast literature. It makes several tested and untested predictions that are unusual. However, habituation cannot explain all contrast. A complete explanation requires postulating that at least one additional mechanism, controlled by the conditions of reinforcement in the following component, also contributes to contrast.     

Intuitions in Conflict: Preference Reversals Due to Switch Between Sensitization and Diminishing Sensitivity

Sensitization occurs when the passage of time increases the intensity of the experience. Individuals have sensitization intuitions for some unpleasant experiences such as waiting and commuting. In contrast, diminishing sensitivity indicates that the impact of each additional unit of a stimulus decreases as the magnitude of the stimulus increases. In this article, we document a new preference reversal phenomenon due to switch between these two intuitions. When considering unpleasant experiences such as waiting and commuting in a judgment task that asks individuals to consider the impact of an additional unit of time to different baselines, we find that individuals respond in a way consistent with a sensitization intuition. However, when asked to make choices involving trade‐offs between longer unpleasant experiences and other attributes, participants respond in a way contrary to their sensitization intuitions and consistent with diminishing sensitivity. We reason that the automatic use of relative differences and diminishing sensitivity occurs because it facilitates trade‐offs considerations in a typical choice task. Our hypotheses are supported in a series of four studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Headache triggers: To avoid or not to avoid,that is the question

Abstract

Traditional clinical advice in the management of headaches is to avoid trigger factors. There is a danger, however, that avoidance of triggers results in a sensitisation process whereby tolerance for the triggers decreases, in a manner analogous to increments in anxiety arising from avoidance of anxiety-eliciting stimuli. Reported here are six single-case experiments in which the aim was to desensitise headache sufferers to an experimentally validated trigger, namely “visual disturbance”. The results demonstrated that repeated, prolonged exposure to a headache trigger led to desensitisation with participants experiencing less visual disturbance, less negative affect and less head pain in response to the trigger. These findings have theoretical significance as they speak to the issue of the aetiology of chronic headache, and practical significance as they suggest that a key aspect of current management may contribute to the disorder becoming worse rather than better.     

阈下语义启动效应影响因素述评

阈下语义启动效应是指阈下呈现的启动词能够对与之有语义联想关系的目标词的加工产生促进作用.阈下语义启动效应具有不稳定性且容易受到各种因素的影响.影响阈下语义启动效应的因素有外部因素和内部因素两大类,外部因素包括任务类型、实验材料和实验程序等因素,内部因素包括注意、任务设置、目的和期望.本文首先简单回顾阈下语义启动效应的研究历史,并介绍相应的研究范式及觉知状态的测量方法,然后重点对影响因素进行了总结和评述.未来的研究可以从优化研究范式、加强脑机制研究以及发展理论等几个方面进一步拓展.     

毒扁豆碱对吗啡导致的大鼠行为敏感化的抑制作用

药物滥用导致的行为敏感化被认为与成瘾过程密切相关。本实验探讨吗啡导致的大鼠行为敏感化与神经递质乙酰胆碱的关系。实验动物分为3组,分别进行生理盐水、吗啡（10.0mg/kg）、吗啡（10.0mg/kg）＋胆碱酯酶抑制剂毒扁豆碱（0.2mg/kg）前处理,36小时腹腔注射4次。前处理结束1周所有动物注射小剂量吗啡（4.0mg/kg）;使用生理盐水前处理的动物,第2周注射毒扁豆碱（0.2mg/kg）;使用吗啡前处理的动物,第2周注射小剂量吗啡＋毒扁豆碱（0.2mg/kg）,第3周再次注射小剂量吗啡。动物每次接受注射后立即记录其在两小时内的活动量(10分钟为一个记录单元)。结果表明,毒扁豆碱既能够抑制吗啡诱导的行为敏感化,也能够阻断小剂量吗啡对行为敏感化的“点燃”作用。由此推论,吗啡导致的行为敏感化与其抑制乙酰胆碱分泌有关。     

Drugs, Environment, Brain, and Behavior

Abstract— The effects of psychoactive drugs are not just a function of their pharmacological actions, but are due to complex interactions among pharmacological, psychological, and environmental factors. We discuss here how drug-environment interactions determine the likelihood that addictive drugs produce a persistent form of neurobehavioral plasticity (sensitization) thought to be involved in the pathophysiology of addiction and relapse.