Unpaired shocks during extinction weaken the contextual renewal of a conditioned discrimination

Extinction is generally more fragile than conditioning, as illustrated by the contextual renewal effect. The traditional extinction procedure entails isolated presentations of the conditioned stimulus. Extinction may be boosted by adding isolated presentations of the unconditioned stimulus, as this should augment breaking the contingency between the two stimuli. In a human conditioning experiment with on-line expectancy ratings and electrodermal responding as dependent variables, 32 participants were differentially conditioned to two neutral figures using electric shock. After a change of context, one group received normal extinction treatment whereas another group received explicitly unpaired presentations of the figures and shock. At test, the two figures were presented in the original context again. For both measures, only the group that received normal extinction showed renewal of the conditioned discrimination. These results suggest that unpaired shocks during extinction strengthen the extinction learning.     

Predator odor avoidance as a rodent model of anxiety: learning-mediated consequences beyond the initial exposure

Prey animals such as rats display innate defensive responses when exposed to the odor of a predator, providing a valuable means of studying the neurobiology of anxiety. While the unconditioned behavioral and neural responses to a single predator odor exposure have been well documented, the paradigm can also be used to study learning-dependent adaptations that occur following repeated exposure to a stressor or associated stimuli. In developing preclinical models for human anxiety disorders this is advantageous, as anxiety disorders seldom involve a single acute experience of anxiety, but rather are chronic and/or recurring illnesses. Part 1 of this review summarizes current research on the three most commonly used predator-related odors: cat odor, ferret odor, and trimethylthiazoline (a component of fox odor). Part 2 reviews the learning-based behavioral and neural adaptations that underlie predator odor-induced context conditioning, one-trial tolerance, sensitization, habituation and dishabituation.     

Visual perceptual learning by operant conditioning training follows rules of contingency

Visual perceptual learning (VPL) can occur as a result of a repetitive stimulus-reward pairing in the absence of any task. This suggests that rules that guide Conditioning, such as stimulus-reward contingency (e.g., that stimulus predicts the likelihood of reward), may also guide the formation of VPL. To address this question, we trained subjects with an operant conditioning task in which there were contingencies between the response to one of three orientations and the presence of reward. Results showed that VPL only occurred for positive contingencies, but not for neutral or negative contingencies. These results suggest that the formation of VPL is influenced by similar rules that guide the process of Conditioning.     

情绪词对新异刺激喜好度变化的调节机制

通过三个实验探讨了情绪词的情绪信息对新异刺激喜好度变化的调节机制。实验采用评价条件化(Evaluative Conditioning)范式, 将新异刺激(相当于条件刺激, CS)与情绪词(相当于无条件刺激, US)配对呈现, 最后测量被试对新异刺激的喜好程度。三个实验通过设置表面故事, 控制新异刺激与情绪词间的配对关系, 并改变任务的加工深度, 揭示了情绪词调节新异刺激喜好度变化的机制。研究结果表明, 情绪词对新异刺激喜好度的调节不依赖于对刺激间偶联关系的意识以及被试的任务状态, 是一种自下而上的自动化的联想学习过程。     

Transgenic inhibition of neuronal calcineurin activity in the forebrain facilitates fear conditioning, but inhibits the extinction of contextual fear memories

It is unclear whether protein phosphatases, which counteract the actions of protein kinases, play a beneficial role in the formation and extinction of previously acquired fear memories. In this study, we investigated the role of the calcium/calmodulin dependent phosphatase 2B, also known as calcineurin (CaN) in the formation of contextual fear memory and extinction of previously acquired contextual fear. We used a temporally regulated transgenic approach, that allowed us to selectively inhibit neuronal CaN activity in the forebrain either during conditioning or only during extinction training leaving the conditioning undisturbed. Reducing CaN activity through the expression of a CaN inhibitor facilitated contextual fear conditioning, while it impaired the extinction of previously formed contextual fear memory. These findings give the first genetic evidence that neuronal CaN plays an opposite role in the formation of contextual fear memories and the extinction of previously formed contextual fear memories.     

Seductive eyes: attractiveness and direct gaze increase desire for associated objects

Recent research in neuroscience shows that observing attractive faces with direct gaze is more rewarding than observing attractive faces with averted gaze. On the basis of this research, it was hypothesized that object evaluations can be enhanced by associating them with attractive faces displaying direct gaze. In a conditioning paradigm, novel objects were associated with either attractive or unattractive female faces, either displaying direct or averted gaze. An affective priming task showed more positive automatic evaluations of objects that were paired with attractive faces with direct gaze than attractive faces with averted gaze and unattractive faces, irrespective of gaze direction. Participants' self-reported desire for the objects matched the affective priming data. The results are discussed against the background of recent findings on affective consequences of gaze cueing.