Probability of shock in the presence and absence of CS in fear conditioning.
01 Aug 1968-Journal of Comparative and Physiological Psychology (J Comp Physiol Psychol)-Vol. 66, Iss: 1, pp 1-5
TL;DR: 2 experiments indicate that CS-US contingency is an important determinant of fear conditioning and that presentation of US in the absence of CS interferes with fear conditioning.
Abstract: 2 experiments indicate that CS-US contingency is an important determinant of fear conditioning and that presentation of US in the absence of CS interferes with fear conditioning. In Experiment 1, equal probability of a shock US in the presence and absence of a tone CS produced no CER suppression to CS; the same probability of US given only during CS produced substantial conditioning. In Experiment 2, which explored 4 different probabilities of US in the presence and absence of CS, amount of conditioning was higher the greater the probability of US during CS and was lower the greater the probability of US in the absence of CS; when the 2 probabilities were equal, no conditioning resulted. Two conceptions of Pavlovian conditioning have been distinguished by Rescorla (1967). The first, and more traditional, notion emphasizes the role of the number of pairings of CS and US in the formation of a CR. The second notion suggests that it is the contingency between CS and US which is important. The notion of contingency differs from that of pairing in that it includes not only what events are paired but also what events are not paired. As used here, contingency refers to the relative probability of occurrence of US in the presence of CS as contrasted with its probability in the absence of CS. The contingency notion suggests that, in fact, conditioning only occurs when these probabilities differ; when the probability of US is higher during CS than at other times, excitatory conditioning occurs; when the probability is lower, inhibitory conditioning results. Notice that the probability of a US can be the same in the absence and presence of CS and yet there can be a fair number of CS-US pairings. It is this that makes it possible to assess the relative importance of pairing and contingency in the development of a CR. Several experiments have pointed to the usefulness of the contingency notion. Rescorla (1966) reported a Pavlovian 1This research was supported by Grants MH13415-01 from the National Institute of Mental Health and GB-6493 from the National Science Foundation, as well as by funds from Yale University.
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TL;DR: A review of the common pathways and mechanisms in invertebrate fear-associated behavioral changes can be found in this paper , where a predator-prey relationship is used to study learned fear in a naturalistic context.
Abstract: Learning to identify and predict threats is a basic skill that allows animals to avoid harm. Studies in invertebrates like Aplysia californica, Drosophila melanogaster, and Caenorhabditis elegans have revealed that the basic mechanisms of learning and memory are conserved. We will summarize these studies and highlight the common pathways and mechanisms in invertebrate fear-associated behavioral changes. Fear conditioning studies utilizing electric shock in Aplysia and Drosophila have demonstrated that serotonin or dopamine are typically involved in relaying aversive stimuli, leading to changes in intracellular calcium levels and increased presynaptic neurotransmitter release and short-term changes in behavior. Long-term changes in behavior typically require multiple, spaced trials, and involve changes in gene expression. C. elegans studies have demonstrated these basic aversive learning principles as well; however, fear conditioning has yet to be explicitly demonstrated in this model due to stimulus choice. Because predator–prey relationships can be used to study learned fear in a naturalistic context, this review also summarizes what is known about predator-induced behaviors in these three organisms, and their potential applications for future investigations into fear conditioning.
1 citations
01 Jan 2009
TL;DR: The results of the first experiment demonstrate for the first time that rapid dopamine release in the NAc is dramatically altered during stimulus-reward learning and revealed that cue-evoked increases in NAc dopamine concentration did not signal reward prediction alone, but reflected the importance of the predictive cue.
Abstract: JEREMY DAY: Cellular and Chemical Dynamics within the Nucleus Accumbens during Reward-related Learning and Decision Making (Under the direction of Regina M. Carelli) The ability to form and maintain associations between environmental cues, actions, and rewarding stimuli is an elementary yet fundamental aspect of learned behavior. Moreover, in order for organisms to optimize behavioral allocation after learning has occurred, such associations must be able to guide decision making processes as animals weigh the benefits and costs of potential actions. Multiple lines of research have identified that reward-related learning and decision making are mediated by a distributed network of brain nuclei that includes the nucleus accumbens (NAc) and its innervation from dopamine neurons located in the midbrain. However, the precise neural processing that underlies this function is unclear. The first set of experiments detailed in this dissertation took advantage of technological advances to characterize patterns of NAc dopamine release in real time, during behavioral performance. The results of the first experiment demonstrate for the first time that rapid dopamine release in the NAc is dramatically altered during stimulus-reward learning. Before learning, reward delivery produced robust increases in NAc dopamine concentration. After learning, these increases had completely transferred to the predictive cue and were no longer present when rewards were delivered. Further experiments revealed that cue-evoked increases in NAc dopamine concentration did not signal reward prediction alone, but reflected the
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Cites background from "Probability of shock in the presenc..."
...However, another critical variable in Pavlovian conditioning involves the contingency between the CS and the US, or the degree to which the CS predicts the US (Rescorla, 1968, 1969, 1988)....
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1 citations
Dissertation•
01 Jan 2011
TL;DR: The work done to enable DynamicWEB to adapt to both concept drift and object drift, both of which are characteristic of many application domains are described.
Abstract: This research was motivated by problems in network security, where an attacker often deliberately changes their identifying information and behaviour in order to camouflage their malicious behaviour. Addressing this problem has resulted in a new adaption to the unsupervised machine learning technique COBWEB.
In machine learning and data mining the aim is to extract patterns from data in order to discover a meaning underlying the processes that are taking place. In most cases, each object is observed once, and then the patterns that have been extracted can be used to classify newly-observed objects. Conceptual clustering aims to do this in such a way that the patterns that are learned are human readable. Concept drift algorithms allow concepts to change over time, although most undertake this in a supervised manner, which presents a challenge when looking for novel classes.
This research focuses on the classification of objects that change over time across multiple observations. The objects may change their own characteristics (labelled as object drift in this research) or maintain the same characteristics, but change their identifier. In addition to this, it is also possible for the concept that describes a group of objects to itself change (known as concept drift). In addition to the possible application within the security domain, the method was generalised and tested across a range of machine learning and data mining domains. In the process it was shown that the method was robust in the presence of concept drift, which occurs when a group of objects that define a given concept change their characteristics, resulting in the definition of that concept having changed over time.
The ideas of concept drift and object drift are not only relevant within the computer security field, but can be of significance in any knowledge domain. Therefore, any method presented to address this learning problem should be generalised enough to be applicable in many application areas.
The new method, entitled DynamicWEB, extends the existing conceptual clustering method COBWEB to allow for profiles to be added and removed from the concept hierarchy. An index structure was implemented using an AVL tree to facilitate fast scalable searching of the knowledge structure. As the target objects change over time the profiles of each target are updated within the structure, maintaining an up-to-date representation of the domain. The profiles contain derived attributes, which are formed across multiple observations of each object, with the aim of retaining knowledge of how the object has changed over time. As well as preserving context over time, Dynamic Web uses multiple trees and so, transforms the learner into an ensemble classifier.
In addition to testing the method on the security and network based datasets, a number of other datasets are also examined. A new dataset (a modified version of Quinlan’s weather dataset) is presented in order to illustrate how Dynamic Web operates in the presence of object drift. The method is also tested on several wellknown machine learning datasets, some of which exhibit concept drift. Along with these artificial datasets, a group of real-world datasets, including several sourced from the Australian Bureau of Statistics, were also examined, illustrating DynamicWEB’s ability to adapt to change.
This thesis describes the work done to enable DynamicWEB to adapt to both concept drift and object drift, both of which are characteristic of many application domains. DynamicWEB is also capable of profiling an object across multiple observations to allow for accurate prediction and inter-object relationship discovery.
1 citations
Cites methods from "Probability of shock in the presenc..."
...The evaluation method is based upon research conducted in the field of psychology examining rats(much like the basis of COBWEB discussed in Chapter 4), and the way they react to viewing novel stimulus and unpleasant stimulus, and the variations between the two (Rescorla 1968)....
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References
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TL;DR: This "truly random" control procedure leads to a new conception of Pavlovian conditioning postulating that the contingency between CS and US, rather than the pairing of CS andUS, is the important event in conditioning.
Abstract: The traditional control procedures for Pavlovian conditioning are examined and each is found wanting. Some procedures introduce nonassociative factors not present in the experimental procedure while others transform the excitatory, experimental CS-US contingency into an inhibitory contingency. An alternative control procedure is suggested in which there is no contingency whatsoever between CS and US. This \"truly random\" control procedure leads to a new conception of Pavlovian conditioning postulating that the contingency between CS and US, rather than the pairing of CS and US, is the important event in conditioning. The fruitfulness of this new conception of Pavlovian conditioning is illustrated by 2 experimental results.
1,328 citations
301 citations
TL;DR: In this paper, three groups of dogs were trained with different kinds of Pavlovian fear conditioning for three different types of dogs: randomly and independently; for a second group, CSs predicted the occurrence of USs; and for a third group, S predicted the absence of the USs.
Abstract: Three groups of dogs were Sidman avoidance trained They then received different kinds of Pavlovian fear conditioning For one group CSs and USs occurred randomly and independently; for a second group, CSs predicted the occurrence of USs; for a third group, CSs predicted the absence of the USs The CSs were subsequently presented while S performed the avoidance response CSs which had predicted the occurrence or the absence of USs produced, respectively, increases and decreases in avoidance rate For the group with random CSs and USs in conditioning, the CS had no effect upon avoidance
160 citations
64 citations
TL;DR: Rats in an experimental group were given 30 trials of differential CER and then the CS+ and CS− were combined during CER extinction, resulting in less suppression for the experimental group than shown by a control group, interpreted as a demonstration of the active inhibitory properties of CS−.
Abstract: Rats in an experimental group were given 30 trials of differential CER and then the CS+ and CS− were combined during CER extinction. The combination resulted in less suppression for the experimental group than shown by a control group which had a CS+ and a formerly random stimulus combined during extinction. This was interpreted as a demonstration of the active inhibitory properties of CS−.
44 citations
"Probability of shock in the presenc..." refers background in this paper
...Although such an account is plausible for the present data, it fails to explain the active inhibition of fear found by Rescorla and LoLordo (1965), Rescorla (1966), and Hammond (1967)....
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