Using progressive ratio schedules to evaluate tokens as generalized conditioned reinforcers

The properties of operant reinforcers are dynamic and dependent on a number of variables, such as schedule and effort. There has been sparse research on the generalized conditioned properties of token reinforcement. We evaluated leisure items, edible items, and tokens using a progressive ratio schedule with three children with diagnoses of ASD and developmental delays. The highest break points occurred during the token reinforcement condition for two out of three participants, but response rates tended to be higher with edibles. We then evaluated the effects of presession access to edibles on the break points of edible items and tokens with two participants. Break points decreased only in the edible reinforcement condition, and the participants chose to work for leisure items rather than edibles when presession access to edibles was in place. These findings suggest that the tokens functioned as generalized conditioned reinforcers.     

Two-factor theory has strong empirical evidence of validity.

Traditional two-factor theory is supported by parallels in the clinical literature. Theoretical problems with two-factor theory are obviated by the role of safety signals, which serve as positive conditioned reinforcers and retard the extinction of conditioned fear.     

情绪应激体液免疫调节作用的影响因素

以给予经定时喂水训练大鼠空瓶刺激为情绪性心理直激源,研究了应激源给予的频率及抗原免疫前或后给予应激刺激等因素对此情绪应激体液免疫调节作用的影响：结果表明,特异性抗原OVA免疫前3次,每次30分钟的情绪应激刺激不影响大鼠的抗OVA抗体水平和脾脏指数;抗原免疫后,同样频率和持续时间的情绪应激能一定程度地降低体液免疫功能;而抗原免疫后14次,每次10分钟的情绪应激刺激则显著降低大鼠的抗OVA抗体水平和脾脏指数。该研究证实,抗原免疫后、反复多次的情绪应激刺激能显著抑制大鼠的原发性体液免疫功能。     

中枢白细胞介素-1在应激升压反应中的作用

分别在乌拉坦麻醉及清醒的雄性SD大鼠观察到：(1)脑室注射IL-113出现升压效应,(2)条件恐惧应激刺激、足电击及脑室注射IL-1β诱发的升压反应均被脑室注射0．5pg的白细胞介素-1拮抗剂IL-1ra明显衰减;(3)静脉注射0．5μgIL-1ra对足电击引起的升压反应无明显影响。以上结果提示中枢IL-1介导条件恐惧应激刺激、及足电击诱发的升压反应。     

Sleep and Immunity: Cytokine Pathways Linking Sleep and Health Outcomes

ABSTRACT— The functions of sleep are enigmatic but are beginning to be delineated. Sleep has been long thought to be important for health, and poor sleep is prospectively associated with worsened health outcomes. Yet the mechanisms accounting for this are only partially understood. In this review, we suggest that the immune system plays a role in the relationship between sleep and health and that sleep processes and immunity show bidirectional interactions, as evidenced in both animal and human studies. Immunological signaling molecules, termed cytokines, are important in coordinating brain–immune system communication, and particular cytokines such as tumor necrosis factor, interleukin-1, and interleukin-6 play a crucial role in sleep regulation. Elevated levels of these cytokines are also associated with a number of chronic diseases and may provide a pathway linking poor sleep with health outcomes.     

The effect of conditioned reinforcement rate on choice: a review

We review the nature of conditioned reinforcement, including evidence that conditioned reinforcers maintain choice behavior in concurrent schedules and that they elevate responding in the terminal links of concurrent‐chains schedules. A question has resurfaced recently: Do theories of choice in concurrent‐chains schedules need to include a term reflecting greater preference for higher rates of conditioned reinforcement? The review of several studies addressing this point suggests that such a term is inappropriate. Elevated rates of conditioned reinforcement (and responding) in the terminal links of concurrent‐chains schedules do not lead to greater preference in the initial link leading to the higher rate of conditioned reinforcement. If anything, the opposite preference is likely to occur. This result is not surprising, since the additional putative conditioned reinforcers in the terminal link are not correlated with a reduction in time to primary reinforcement nor with an increase in value.     

RESISTANCE TO CHANGE AND FREQUENCY OF RESPONSE‐DEPENDENT STIMULI UNCORRELATED WITH REINFORCEMENT

Stimuli uncorrelated with reinforcement have been shown to enhance response rates and resistance to disruption; however, the effects of different rates of stimulus presentations have not been assessed. In two experiments, we assessed the effects of adding different rates of response‐dependent brief stimuli uncorrelated with primary reinforcement on relative response rates and resistance to change. In both experiments, pigeons responded on variable‐interval 60‐s schedules of food reinforcement in two components of a multiple schedule, and brief response‐dependent keylight‐color changes were added to one or both components. Although relative response rates were not systematically affected in either experiment, relative resistance to presession feeding and extinction were. In Experiment 1, adding stimuli on a variable‐interval schedule to one component of a multiple schedule either at a low rate (1 per min) for one group or at a high rate (4 per min) for another group similarly increased resistance to disruption in the components with added stimuli. When high and low rates of stimuli were presented across components (i.e., within subjects) in Experiment 2, however, relative resistance to disruption was greater in the component presenting stimuli at a lower rate. These results suggest that stimuli uncorrelated with food reinforcement do not strengthen responding in the same way as primary reinforcers.     

SOME EFFECTS OF PROCEDURAL VARIATIONS ON CHOICE RESPONDING IN CONCURRENT CHAINS

The present research used pigeons in a three‐key operant chamber and varied procedural features pertaining to both initial and terminal links of concurrent chains. The initial links randomly alternated on the side keys during a session, while the terminal links always appeared on the center key. Both equal and unequal initial‐link schedules were employed, with either differential or nondifferential terminal‐link stimuli across conditions. The research was designed to neutralize initial‐ and terminal‐link spatial cues in order to gain a clearer understanding of the roles of conditioned reinforcement and delayed primary reinforcement in choice. With both equal and unequal initial links and with differential terminal‐link stimuli, all pigeons reliably preferred the chain with the shorter terminal link. However, with equal initial links and nondifferential stimuli, all pigeons were indifferent. With unequal initial links and nondifferential stimuli, some pigeons were also indifferent, while others actually reversed and preferred the chain with the shorter initial link, even though it was followed by the longer terminal link. The decrease if not reversal of the previous preferences implies that preferences in concurrent chains are a function of the conditioned reinforcement afforded by terminal‐link stimuli, rather than delayed primary reinforcement.     

Comparing the reinforcing efficacy of tokens and primary reinforcers

Token economies are one of the most commonly used behavior-analytic interventions. Despite literature supporting the use of tokens as tools for behavior change, little is known about the efficacy of tokens compared to that of the items for which they are exchanged. Results of previous research comparing the reinforcing efficacy of tokens and primary reinforcers have shown that both produce similar effects on responding. However, published findings have been confounded given the inclusion of primary reinforcers in the token-reinforcer test conditions. In this study, we established novel tokens as reinforcers. We then conducted a conditioned-reinforcer assessment using a tandem control to ensure that the tokens functioned as reinforcers. We used progressive-ratio schedules to compare the reinforcing efficacy of the tokens to high- and low-preference edibles that were also used as backup reinforcers. For both participants, we found that high-preference primary reinforcers maintained higher response frequencies than did tokens.     

味觉厌恶性条件反射建立后脑内c-Fos的表达

以新异味觉刺激糖精水的摄入为条件刺激,以腹腔注射环磷酰胺(CY,免疫抑制剂)或氯化锂(LiCl)为非条件刺激,分别使大鼠建立味觉厌恶性条件反射.在条件刺激日,糖精水在学习组大鼠下列脑区中诱发出密集的Fos表达下丘脑、杏仁核、边缘皮质等,而非学习组在这些区域中却没有或只有少量表达.另外,在丘脑前背侧核、扣带回、下丘脑外侧核、穹隆下器、压部后颗粒皮质、视上核,CY组的Fos表达明显多于LiCl组;而在伏核、杏仁基底外侧核、腹外侧隔核,LiCl组的Fos表达明显多于CY组,这种差异可能是两种药物的不同药理性质所致.