Mere Exposure: A Gateway to the Subliminal

In the mere-repeated-exposure paradigm, an individual is repeatedly exposed to a particular stimulus object, and the researcher records the individual's emerging preference for that object. Vast literature on the mere-repeated-exposure effect shows it to be a robust phenomenon that cannot be explained by an appeal to recognition memory or perceptual fluency. The effect has been demonstrated across cultures, species, and diverse stimulus domains. It has been obtained even when the stimuli exposed are not accessible to the participants' awareness, and even prenatally. The repeated-exposure paradigm can be regarded as a form of classical conditioning if we assume that the absence of aversive events constitutes the unconditioned stimulus. Empirical research shows that a benign experience of repetition can in and of itself enhance positive affect, and that such affect can become attached not only to stimuli that have been exposed but also to similar stimuli that have not been previously exposed, and to totally distinct stimuli as well. Implications for affect as a fundamental and independent process are discussed in the light of neuroanatomical evidence.     

Projection of the Magnocellular Red Nucleus to the Region of the Accessory Abducens Nucleus in the Rabbit

The projection of the magnocellular red nucleus (RNm) to the region of the accessory abducens nucleus (AABD) was traced in rabbit using the bidirectional tracer wheat germ agglutinin-horseradish peroxidase (WGA-HRP). In one set of animals, recordings of antidromic responses from RNm neurons elicited by electrical stimulation of the rubrospinal tract were used to localize injections of WGA-HRP for orthograde labeling of RNm terminals. In a different set of animals, horseradish peroxidase was injected into the retractor bulbi muscle to retrogradely label motoneurons of the AABD. The positions of RNm fibers and terminals were examined and compared to the locations and distribution of AABD cell bodies and labeled dendrites. Analyses revealed that along the entire rostrocaudal extent of the AABD, RNm efferents terminate primarily lateral to, or in the lateral aspects of, labeled motoneurons. For the rostral AABD, RNm efferents terminate only lateral to the nucleus. Although the terminals are not positioned to contact cell bodies of the AABD, they could overlap with dendrites that extend in the lateral direction. RNm efferents terminate more extensively within the posterior AABD, overlapping within both dendritic and cell body regions of the nucleus. Even in this posterior region, however, RNm efferents were distributed primarily over the lateral half of the nucleus. These data show that RNm can monosynaptically influence the AABD, through primarily its lateral and posterior aspects. Our findings also show that a major target of RNm efferents is the reticular cell population located lateral to the AABD, suggesting that the RNm also may affect AABD motoneuronal output indirectly through its projection to reticular cells.     

Effects of Early Hippocampal Lesions on Trace, Delay, and Long-Delay Eyeblink Conditioning in Developing Rats

The effects of bilateral hippocampal aspiration lesions on later acquisition of eyeblink conditioning were examined in developing Long-Evans rat pups. Lesions on postnatal day (PND) 10 were followed by evaluation of trace eyeblink conditioning (Experiment 1) and delay eyeblink conditioning (Experiment 2) on PND 25. Pairings of a tone conditioned stimulus (CS) and periocular shock unconditioned stimulus (US, 100 ms) were presented in one of three conditioning paradigms: trace (380 ms CS, 500 ms trace interval, 880 ms interstimulus interval [ISI]), standard delay (380 ms CS, 280 ms ISI), or long delay (980 ms CS, 880 ms ISI). The results of two experiments indicated that hippocampal lesions impaired trace eyeblink conditioning more than either type of delay conditioning. In light of our previous work on the ontogeny of trace, delay, and long-delay eyeblink conditioning (Ivkovich, Paczkowski, & Stanton, 2000) showing that trace and long-delay eyeblink conditioning had similar ontogenetic profiles, the current data suggest that during ontogeny hippocampal maturation may be more important for the short-term memory component than for the long-ISI component of trace eyeblink conditioning. The late development of conditioning over long ISIs may depend on a separate process such as protracted development of cerebellar cortex.     

作为认知渗透现象的安慰剂镇痛作用

安慰剂镇痛作用在医学领域已经得到了广泛的认可,医学界提出条件反射理论和期望理论来解释安慰剂镇痛作用,然而这两种理论无法在学界达成统一。对安慰剂镇痛作用的机制以及认知渗透现象进行比较,通过对认知渗透现象的定义和性质的分析,提出安慰剂镇痛作用是一种认知渗透现象,并提出认知渗透理论可以从哲学的视角为安慰剂镇痛提供系统的理论框架,进而为医学工作者在医学活动和临床实践中的深度研究提供系统的研究思路和理论框架。

     

Augmentation: Synergistic Conditioning in Taste-Aversion Learning

Recent work in taste-aversion learning has revealed a new phenomenon in classical conditioning. When a preconditioned gustatory cue (taste or odor) is conditioned in compound with a second gustatory cue, conditioning to the second cue is augmented. This enhanced conditioning of the second cue is noteworthy because studies with other forms of classical conditioning have shown blocked conditioning to the second cue. This new phenomenon has been termed augmentation , and it has implications for the study of taste and odor interactions, formal models of learning, and clinical interventions with cancer patients.     

Contextual fear conditioning predicts subsequent avoidance behaviour in a virtual reality environment

Avoidance behaviour is a crucial component of fear and is importantly involved in the maintenance of anxiety disorders. Presumably, fear conditioning leads to avoidance of the feared object or context. A virtual reality contextual fear conditioning paradigm was used to investigate the association between explicit conditioning effects and subsequent avoidance behaviour. Mild electric shocks were administered in one context (anxiety context), but never in a second context (safety context). Subsequent avoidance behaviour was assessed by asking participants to choose two out of three contexts (a neutral context was added) to visit again. Participants avoided the anxiety context, but did not prefer the safety over the neutral context. Participants with substantial conditioning effects, as reflected in differential valence, arousal and anxiety ratings, avoided the anxiety context but not the safety context. In sum, we demonstrated an association between context conditioning effects on an explicit level and later avoidance behaviour.     

Exposure to a novel context after extinction causes a renewal of extinguished conditioned responses: Implications for the treatment of fear

Renewal gives an experimental model for the relapse of fear symptoms following exposure therapy. While renewal of extinguished fear in humans has been observed following a return to the original context in which fear was acquired (ABA design), it has been more difficult to show upon presentation of a novel context (ABC design). The present experiment used a particularly strong context manipulation in a fear conditioning procedure. Context was manipulated by using large photographs of real environments taken from various angles and was present throughout the entire experiment. A renewal of cognitive expectancy was found in both ABA and ABC renewal designs, although it was larger in the former than in the latter. Response times in making the expectancy judgments increased when there was a change to a new context. The results demonstrate consistency in fear renewal effects between human and animal studies and suggest that relapse following exposure therapy via renewal remains a danger when people encounter a previously feared object in a novel context.     

Mechanics of the animate.

Behavior is treated as basic physics. Dimensions are identified and their transformations from physical specification to axes in behavioral space are suggested. Responses are treated as action patterns arrayed along a continuum of activation energy. Behavior is seen as movement along a trajectory through this behavior space. Incentives or reinforcers are attractors in behavior space, at the centers of basins of lowered potential. Trajectories impinging on such basins may be captured; repeated capture will warp the trajectory toward a geodesic, a process called conditioning. Conditioning is enhanced by contiguity, the proximity between the measured behavior and the incentive at the end of the trajectory, and by contingency, the depth of the trajectory below the average level of the potential energy landscape. Motivation is seen as the potential of an organism for motion under the forces impinging on it. Degree of motivation is characterized by the depth of the potential field, with low motivation corresponding to a flat field and a flat gradient of activation energy. Drives are the forces of incentives propagated through behavior space. Different laws for the attenuation of drive with behavioral distance are discussed, as is the dynamics of action. The basic postulate of behavior mechanics is incentive-tracking in behavior space, the energy for which is provided by decreases in potential. The relation of temporal gradients to response differentiation and temporal discrimination is analyzed. Various two-body problems are sketched to illustrate the application of these ideas to association, choice, scalar timing, self-control, and freedom.     

Cognition and Emotion,Volume 24, 2010, List of Reviewers

The tendency for anxious individuals to selectively attend to threatening information is believed to cause and exacerbate anxious emotional responding in a self-perpetuating cycle. The present study sought to examine the relation between differential interoceptive conditioning (IC) using carbon dioxide inhalation as a panicogenic unconditioned stimulus (US) and the development of Stroop colour-naming interference to various non-word conditioned stimuli (CSs). Healthy university students (N = 27) underwent the assessment of colour-naming interference to reinforced CS+ and non-reinforced CS? non-words prior to and following differential fear conditioning. Participants showed greater magnitude electrodermal and verbal-evaluative responses to the CS+ over the CS? non-word following IC, and demonstrated the expected slower colour-naming latencies to the CS+ compared to the CS? non-word from baseline to post-conditioning. We discuss the relation between fear learning and the emergence of attentional bias for threat to further understand the maintenance of anxiety disorders.     

恐惧情绪对大鼠学习记忆的影响

通过对４组不同处理背景动物操作条件学习的实验研究,观察强噪音下恐惧情绪对动物学习、记忆的影响以及怎样通过系统脱敏来减少恐惧在其中的作用。结果发现：恐惧组大鼠的操作条件学习具有第一次联系（健盘与食物之间）成功所需时间短、旧技能遗忘快、重新学习次数多和学习成绩差等特征;恐惧组大鼠与学习无关的恐惧行为增多,严重干扰学习的控制加工过程,影响学习任务完成;强噪音脱敏组大鼠学习过程、学习成绩的各项指标与控制组无差异。