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The basolateral amygdala (BLA) is thought to be essential for fear learning. However, extensive training can overcome the loss of conditional fear evident following lesions and inactivation of the BLA. Such results suggest the existence of a primary BLA-dependent and a compensatory BLA-independent neural circuit. We tested the hypothesis that the bed nuclei of the stria terminalis (BST) provides this compensatory plasticity. Using extensive context-fear conditioning, we demonstrate that combined BLA and BST lesions prevented fear acquisition and expression. Additionally, protein synthesis in the BST was critical only for consolidation of BLA-independent but not BLA-dependent fear. Moreover, fear acquired after BLA lesions resulted in greater activation of BST regions that receive hippocampal efferents. These results suggest that the BST is capable of functioning as a compensatory site in the acquisition and consolidation of context-fear memories. Unlocking such neural compensation holds promise for understanding situations when brain damage impairs normal function or failure to regulate compensatory sites leads to anxiety disorders. amygdala | basolateral amygdala | context | plasticity | bed nucleus of the stria terminalis doi/ 10.10731pnas.1005754107

At both empirical and theoretical levels, multiple functional roles of contextual information upon memory performance have been proposed without a clear dissociation of these roles. Some theories have assumed that contexts are functionally similar to cues, whereas other views emphasize the retrieval facilitating properties of contextual information. In Experiment 1, we observed that one critical parameter, the spacing of trials, could determine whether the context would function as a conditioned stimulus or as a retrieval cue for memories trained in different phases. Experiments 2 and 3 doubly dissociated these functions by selectively disrupting one role but not the other, and vice versa. Overall, these observations identify one determinant of different functions of contextual information and pose a major challenge to theories of learning that assume exclusively one or the other function of the context. Moreover, these data emphasize the importance of parametric variations on behavioral control, which has critical implications for studies designed to understand the role of the hippocampus in processing of contextual attributes. Keywords: Pavlovian fear conditioning, contextual information, occasion setter, double dissociation, trial spacing DOI: 10.1037/a0017298

Three lick suppression experiments with rats investigated backward blocking in first-order conditioning. As has been suggested in prior studies, the experiments demonstrated that backward blocking is difficult to obtain in conventional first-order conditioning situations. However, the authors demonstrate here that backward blocking is observed in first-order conditioning if the target cue's behavioral control is weak at the time of elemental training of the blocking cue. The target cue's behavioral control was weakened through forward blocking of the target cue by a third cue (Experiment 1), conducting compound and elemental training with backward temporal relationships to the unconditioned stimulus (Experiment 2), and extinguishing the target cue following compound training (Experiment 3). The results of these experiments suggest that weak control of behavior by the blocked cue at the time of elemental training of the blocking cue is a critical determinant of whether blocking can be observed. Prior failures to detect backward blocking in first-order conditioning are seemingly due to a difficulty in decreasing the response-eliciting potential of a cue by indirect means such as associative inflation of a competing cue. Keywords: backward blocking, retrospective revaluation, cue competition, Pavlovian conditioning, biological significance DOI: 10.1037/a0016773

Underwater vibratory sources simultaneously present acoustic and hydrodynamic disturbances. Because vibratory dipole sources are poor sonic projectors, most researchers have assumed that such sources are of greatest relevance to the lateral line system. Both hydroacoustic principles and empirical studies have shown that dipole sources are also a potent stimulus to the inner ear. Responses to vibratory sources in mottled sculpin (Cottus bairdi) were assessed using unconditioned orienting, differential and nondifferential conditioning. Orienting responses are dominated by lateral line inputs and eliminated by lateral line inactivation. Simple conditioning depends on inputs from other systems and was not affected by lateral line inactivation. Differential conditioning alters behavioral control, and sculpin could be conditioned to ignore substrate-borne vibrations and respond only to hydroacoustic stimulation of the ear. The lateral line and inner ear of mottled sculpin do not necessarily exhibit range fractionation, as both systems operate over a similar distance (within 1.5 body lengths) and respond to many of the same sources. Vibratory dipole sources generate compound stimuli that simultaneously activate multiple octavolateralis systems, and sculpin make use of the channels differentially under different behavioral tasks. Keywords: auditory, lateral line, octavolateralis, multisensory DOI: 10.1037/a0016747

One way to minimize excitation acquired by the conditioned stimulus (CS) is to introduce intertrial presentations of the unconditioned stimulus (US). However, even in the presence of frequent intertrial USs. Experiments 1a and 1b found that rats anticipated the customary arrival time of a food pellet US when it occurred before (embedded)--versus coincident with (delay)--the termination of a white noise CS. Delay conditioning emerged in Experiment 2 in the absence of intertrial USs; hence, the detrimental effects of intertrial USs depended on the CS-US relationship, delay versus embedded, and not the duration of CS-US interval. Experiments 3a, 3b, and 4 found that random USs located in the early portion of the intertrial interval increased the control acquired by contextual stimuli at the expense of temporal stimuli occasioned near CS termination. Our results suggest that delay relationships leave the CS especially vulnerable to the deleterious effects of intertrial USs. Keywords: delay conditioning, scalar timing, contingency, contiguity, real-time models DOI: 10.1037/a0016922

The hippocampus and cerebellum are critically involved in trace eyeblink classical conditioning (EBCC). The mechanisms underlying the hippocampal-cerebellar interaction during this task are not well-understood, although hippocampal theta (3-7 Hz) oscillations are known to reflect a favorable state for EBCC. Two groups of rabbits received trace EBCC in which a brain-computer interface administered trials in either the explicit presence or absence of naturally occurring hippocampal theta. A high percentage of robust theta led to a striking enhancement of learning accompanied by rhythmic theta-band (6-7 Hz) oscillations in the interpositus nucleus (IPN) and cerebellar cortex that were time-locked both to hippocampal rhythms and sensory stimuli during training. Rhythmic oscillations were absent in the cerebellum of the non-theta group. These data strongly suggest a beneficial impact of theta-based coordination of hippocampus and cerebellum and, importantly, demonstrate that hippocampal theta oscillations can be used to index, and perhaps modulate, the functional properties of the cerebellum. brain-computer interface | eyeblink classical conditioning | local field potentials | interpositus nucleus | cerebellar cortex doi/ 10.1073/pnas.0908403106

The past 50 years have seen an accumulation of evidence suggesting that associative learning depends on high-level cognitive processes that give rise to propositional knowledge. Yet, many learning theorists maintain a belief in a learning mechanism in which links between mental representations are formed automatically. We characterize and highlight the differences between the propositional and link approaches, and review the relevant empirical evidence. We conclude that learning is the consequence of propositional reasoning processes that cooperate with the unconscious processes involved in memory retrieval and perception. We argue that this new conceptual framework allows many of the important recent advances in associative learning research to be retained, but recast in a model that provides a firmer foundation for both immediate application and future research. Keywords: association; associative link; automatic; awareness; conditioning; controlled; dual-system; human associative learning; propositional

In six experiments, we investigated the influence of featural differences between targets and distractors on the detection and identification of dissimilar and repeated targets in conditions that typically produce an attentional blink and repetition blindness (when a target is repeated). Rapid serial visual presentation streams were presented that contained letter targets and distractors that were either letters or digits. The targets and the distractors were either the same color or a different color and were presented either in the same font or in a different font. Dual-target performance on nonrepeat trials was strongly enhanced when the targets were colored. In addition, when subjects used either the color or the font cues to select the targets, there was benefit of repetition on dual-target report, instead of repetition blindness. The results suggest that featural differences between targets and distractors play an important role in registering stimuli as distinct objects.

Three experiments examined inhibitory learning in rats, using Pavlovian and differential inhibitory eyeblink conditioning procedures. Experiment 1 was designed to compare summation and retardation effects following Pavlovian conditioned inhibition (A+/XA-) or differential inhibition (A+/X-) training using auditory and visual conditioned stimuli (CSs). After ten 100-trial sessions of training, both Pavlovian conditioned inhibition and differential inhibition produced a retardation effect. However, a summation effect was obtained only for rats given Pavlovian conditioned inhibition training. Experiment 2 showed that increasing differential inhibition training to twenty 100-trial sessions produced summation and retardation effects. In Experiment 3, rats were trained with either ten or twenty 100-trial sessions of intramodal inhibitory training with two tone CSs (2 kHz vs. 8 kHz). Summation and retardation effects were obtained after only 20 sessions of differential conditioning. The findings indicate that extensive training is needed to establish conditioned inhibition with intermodal or intramodal differential conditioning.

Auditory fear memory is thought to be maintained by fear conditioning-induced potentiation of synaptic efficacy, which involves enhanced expression of surface AMPA receptor (AMPAR) at excitatory synapses in the lateral amygdala (LA). Depotentiation, reversal of conditioning-induced potentiation, has been proposed as a cellular mechanism for fear extinction; however, a direct link between depotentiation and extinction has not yet been tested. To address this issue, we applied both ex vivo and in vivo approaches to rats in which fear memory had been consolidated. A unique form of depotentiation reversed conditioning-induced potentiation at thalamic input synapses onto the LA (T-LA synapses) ex vivo. Extinction returned the enhanced T-LA synaptic efficacy observed in conditioned rats to baseline and occluded the depotentiation. Consistently, extinction reversed conditioning-induced enhancement of surface expression of AMPAR subunits in LA synaptosomal preparations. A GluR2-derived peptide that blocks regulated AMPAR endocytosis inhibited depotentiation, and microinjection of a cell-permeable form of the peptide into the LA attenuated extinction. Our results are consistent with the use of depotentiation to weaken potentiated synaptic inputs onto the LA during extinction and provide strong evidence that AMPAR removal at excitatory synapses in the LA underlies extinction. lateral amygdala | fear conditioning | AMPA receptor | endocytosis

ABSTRACT. The authors examined 13 skilled, 13 recreational, and 11 novice players' awareness of the advance visual information that they used to judge tennis serve direction. Participants viewed video clips [...]

Honeybees (Apis mellifera) were classically conditioned with odor as conditioned stimulus (CS), sucrose as unconditioned stimulus (US), and proboscis extension as response. The purpose of Experiment 1 (Ns = 26 and 27) was to look for facilitation of forward conditioning by CS-US overlap, but rapid conditioning without overlap left little room for improvement. In 2 further experiments, CS and US were simultaneous, and response to odor alone was measured in subsequent tests. In Experiment 2, a Simultaneous group (N = 25) responded more to the training odor than did an Unpaired control group (N = 25). In Experiment 3, a differentially conditioned Simultaneous group (N = 29) responded more to an odor paired with sucrose in training (S+) than to an odor presented alone (S-). The implications of the results for the problem of the role of amount of reward in honeybee learning are considered.

Successful bidirectional selective breeding of Drosophila melanogaster for excitatory conditionabili is reported, using the reliable measures of individual differences first described by Holliday & Hirsch, 1984, 1986a, 1986b) to test 1,324 animals. Bidirectional selective breeding for good and poor conditioning has produced, respectively, one population in which the percentage of animals showing good conditioning has increased over 25 generations from 19% to 77% and another in which it has decreased over 23 generations to 0%-4%. No increase in a measure of sensitization induced by an unconditioned stimulus (the central excitatory state) accompanied the increase in the percentage of good conditioners in the population selected for good conditioning whose level of conditioned responding exceeds that of the sensitization measure.

Implicit self-esteem is the automatic, nonconscious aspect of self-esteem. This study demonstrated that implicit self-esteem can be increased using a computer game that repeatedly pairs self-relevant information with smiling faces. These findings, which are consistent with principles of classical conditioning, establish the associative and interpersonal nature of implicit self-esteem and demonstrate the potential benefit of applying basic learning principles in this domain.

The cue-duration effect (i.e., longer cues result in less conditioned responding than shorter cues) was examined as a function of whether cues were trained alone or in compound. Compound (AX) or elemental (X) cues of either long or short duration were paired with the unconditioned stimulus. In testing with X alone, the cue-duration effect was observed with elementally trained cues, but not with compound cues. Instead, stronger responding resulted from training with long compound cues relative to short compound cues (i.e., a reversed cue-duration effect). Moreover, an overshadowing effect (i.e., decreased responding due to compound conditioning) was observed when conditioning was conducted with a short cue, but compound conditioning resulted in enhanced responding when it was conducted with a long cue (i.e., reversed overshadowing). These findings are consistent with other recent demonstrations that some laws of learning that apply to elementally trained cues do not similarly apply to cues trained in compound.

Research indicates that cue exposure treament is a beneficial treament for the prevention of addicive behavior relapse if retrieval cues are incorporaed into the treatment protocol.

An attentional-associative model (Schmajuk et al. 1996), previously evaluated against multiple sets of classical conditioning data, is applied to causal learning. In agreement with Mitchell et al.'s suggestion, according to the model associative learning can be a conscious, controlled process. However, whereas our model correctly predicts blocking following or preceding subadditive training, the propositional approach cannot account for those results.

The extent to which human learning should be thought of in terms of elementary, automatic versus controlled, cognitive processes is unresolved after nearly a century of often fierce debate. Mitchell et al. provide a persuasive review of evidence against automatic, unconscious links. Indeed, unconscious processes seem to play a negligible role in any form of learning, not just in Pavlovian conditioning. But a modern connectionist framework, in which 'cognitive' phenomena are emergent properties, is likely to offer a fuller account of human learning than the propositional framework Mitchell et al. propose.

Studies of conditioning in simple systems are best interpreted in terms of the formation of excitatory links. The mechanisms responsible for such conditioning contribute to the associative learning effects shown by more complex systems. Ira dual-system approach is to be avoided, the best hope lies in developing standard associative theory to deal with phenomena said to show propositional learning.

Additional support is presented for the necessity of awareness of the CS-US relation in human autonomic conditioning, However, possible limitations and exceptions regarding this general rule are discussed. Limitations include the lack of relationship between conditioned response (CR) strength and degree of awareness, and an important exception may be the finding of conditioning with backwardly masked CSs of a biologically prepared nature.

We discuss findings on evaluative conditioning (EC) that are problematic for the 'conscious reasoning/propositional knowledge' account of learning, namely, dissociations between conscious beliefs and acquired (dis)liking. We next argue that, both for EC and for Pavlovian learning in general, conditioned responding cannot rationally be inferred from propositional knowledge type 'CS refers to/signals US,' and that, therefore, performance cannot be explained.

Memories that trigger fear can last for years. In some cases they can be overwhelming, for example in post-traumatic stress disorder. A team at New York University, led by psychologist [...]

The propositional nature of human associative learning is strongly supported by studies of trace eyeblink and fear conditioning, in which awareness of the contingency of a conditioned stimulus upon an unconditioned stimulus is a prerequisite for successful learning. Studies of animal lesion and human imaging suggest that tile hippocampus is critical for establishing functional connections between awareness and trace conditioning.

Research involving classical conditioning (CC) usually follows two distinct approaches, exteroceptive and interoceptive (Razran, 1971). Exteroceptive CC research has been the most abundant and employs external stimuli of which the subject is consciously aware. Interoceptive CC involves a conditioned stimulus (CS) which stimulates internal organs producing conditioned responses (CR) and occurs at a lower level than conscious awareness. Ideational conditioning is neither interoceptive nor exteroceptive as the CS exists only as a thought in the mind of the individual. An experiment similar to Mehmet's (1986) involving two groups of undergraduates in psychology was performed. In Phase 1 each subject was presented 32 slides depicting simple arithmetic problems (8 addition, 8 subtraction, 8 division, and 8 multiplication) of the form '2x4 = ?'. Of these 16 resulted in the answer '8' and half of each computational type resulted in this answer also. When arithmetic problems equalling '8' were shown, they were paired with an aversive stimulus, a loud 115-dB tone at 1000 Hz, yielding electrodermal responses. Group 1 (n = 14) was conditioned using ideational stimuli (i.e., the thought of '8' as the CS) in which the digit '8' was never physically shown. Group 2 (n = 12) was conditioned using exteroceptive stimuli as the CS, in which the digit '8' was physically shown. In Phase 2, subjects were shown a further 32 slides, eight of which resulted in the answer '8', eight which showed properties of 'eightness,' e.g., an octagon or the word 'EIGHT,' and a further 16 control non'8' slides. Phase 2 was conducted without the use of aversive stimulus. Electrodermal activity was measured throughout the experiment as an index of conditioning to overcome problems of reporting bias in subjects. Both Group 1 (t = 4.49) and Group 2 (t = 4.19) showed significant conditioning (p = .01). Both groups not only demonstrated conditioning to '8' but also concepts of '8' (generalizations), e.g., an octagon. These findings indicate unequivocally that relations and processes of the mind are amendable to classical conditioning and that they be considered as a step to bridging the congnitive-behaviourist divide.