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Journal ArticleDOI

Rapid associative learning: conditioned bradycardia and its central nervous system substrates.

TL;DR: The present review describes research in the laboratory that has focused on conditioned bradycardia as a model system of a rapidly acquired associative system and contrast it with the more slowly acquired Pavlovian conditioned eyeblink response.
Abstract: It has become clear from the study of different response systems during classical conditioning that some responses are acquired quite rapidly and others show a much slower rate of acquisition. The most often studied rapidly acquired responses have been classically conditioned autonomic changes (e.g., heart rate); the slowly acquired responses most often studied are skeletal responses, such as the eyeblink or leg flexion response. Although there are various other differences between rapidly acquired and slowly acquired responses, we have suggested that the most important difference is the possibility that they represent different stages of the learning process. In the present review I describe research in our laboratory that has focused on conditioned bradycardia as a model system of a rapidly acquired associative system and contrast it with the more slowly acquired Pavlovian conditioned eyeblink response. I also describe the generality of conditioned bradycardia and discuss the differential role of subdivisions of the prefrontal cortex as a substrate for mediating this response. Finally, I briefly discuss the other brain areas involved in conditioned bradycardia, and its functional significance as it relates to the learning process.
Citations
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Journal ArticleDOI
TL;DR: The effects of electrolytic vmPFC lesions made before training on the acquisition, extinction, and recovery of conditioned fear responses in a 2 d experiment suggest a role of thevmPFC in consolidation of extinction learning or the recall of contexts in which extinction took place.
Abstract: Conditioned fear responses to a tone paired with footshock extinguish when the tone is presented repeatedly in the absence of shock. Rather than erase the tone–shock association, extinction is thought to involve new learning accompanied by inhibition of conditioned responding. Despite much interest in extinction from a clinical perspective, little is known about the neural circuits that are involved. Although the prefrontal cortex has a well established role in the inhibition of inappropriate behaviors, previous reports have disagreed as to the role of the ventromedial prefrontal cortex (vmPFC) in extinction. We have reexamined the effects of electrolytic vmPFC lesions made before training on the acquisition, extinction, and recovery of conditioned fear responses in a 2 d experiment. On Day 1 vmPFC lesions had no effect on acquisition or extinction of conditioned freezing and suppression of bar pressing. On Day 2 sham rats recovered only 27% of their acquired freezing, whereas vmPFC-lesioned rats recovered 86%, which was indistinguishable from a control group that never received extinction. The high recovery in lesioned rats could not be attributed to decreased motivation or altered sensitivity to footshock. vmPFC lesions that spared the caudal infralimbic (IL) nucleus had no effect. Thus, the vmPFC (particularly the IL nucleus) is not necessary for expression of extinction, but it is necessary for the recall of extinction learning after a long delay. These data suggest a role of the vmPFC in consolidation of extinction learning or the recall of contexts in which extinction took place.

925 citations


Cites background from "Rapid associative learning: conditi..."

  • ...…(Sesack et al., 1989; Hurley et al., 1991), which plays a key role in the expression of behavioral and autonomic indices of conditioned fear (Kapp et al., 1979; LeDoux et al., 1988; Helmstetter, 1992; McCabe et al., 1992; Powell, 1994; Campeau and Davis, 1995; Maren, 1999; Amorapanth et al., 2000)....

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  • ..., 1991), which plays a key role in the expression of behavioral and autonomic indices of conditioned fear (Kapp et al., 1979; LeDoux et al., 1988; Helmstetter, 1992; McCabe et al., 1992; Powell, 1994; Campeau and Davis, 1995; Maren, 1999; Amorapanth et al., 2000)....

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  • ...Powell and colleagues have shown that mPFC lesions block heart rate conditioning in rabbits (Buchanan and Powell, 1982; Powell, 1994), but ventral mPFC lesions similar to ours had no effect (Powell et al., 1994)....

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Journal ArticleDOI
TL;DR: The results suggest that mPFC processing of Pavlovian conditioning contingencies affects not only the autonomic component of learning but preservative somatomotor conditioning as well, whereas ACN processing affects only the autonomousic component.

53 citations

Journal ArticleDOI
TL;DR: CRM may force us to reevaluate the behavioral and neural consequences of classical conditioning and may have important consequences for the treatment of conditions such as posttraumatic stress disorder.
Abstract: Interest in classical conditioning is usually focused on anticipatory responses to a stimulus associated with a significant event, and it is assumed that responses to the event itself are reflexive, involuntary, and relatively invariant. However, there is compelling evidence that both the rabbit nictitating membrane response (NMR) and heart rate response (HR), well-known reflexive reactions to aversive events, can change quite dramatically as a function of learning when measured in the absence of the conditioned stimulus. In the case of NMR conditioning, a simple blink is transformed into a larger and more complex response. For HR conditioning, reflexive heart rate acceleration can actually change to heart rate deceleration. In both cases, the reflex comes to resemble the conditioned response and follows some of the same behavioral laws. This change in response to the aversive event itself or weaker forms of that event is called conditioning-specific reflex modification (CRM). CRM may force us to reevaluate the behavioral and neural consequences of classical conditioning and may have important consequences for the treatment of conditions such as posttraumatic stress disorder.

30 citations

Journal ArticleDOI
TL;DR: Examination of extracellular activity of single units in the MGN during differential auditory trace conditioning of the rabbit nictitating membrane response suggests that MGN neurons are involved in the maintenance of a sensory memory trace and possibly play a part in CR generation and timing.
Abstract: In classical trace conditioning the acquisition of a conditioned response (CR) is possible even though an interval (the trace interval) elapses between the conditioned stimulus (CS) and unconditioned stimulus (US). This implies that some neural representation of the CS (the stimulus trace) is able to support association between the two stimuli. The medial geniculate nucleus (MGN), particularly the medial division (mMGN), has been identified as one site in the auditory pathway where associative related changes in neural activity occur. If neurons in the MGN are involved in such a sensory trace and in acquisition of a CR, then it is expected that activity following an acoustic CS should be related to both stimulus and response. This study examined the extracellular activity of single units in the MGN during differential auditory trace conditioning of the rabbit nictitating membrane response (NMR). Two 150-ms tones (600 Hz and 1200 Hz) served as CS+ and CS–, and the US was periorbital electrostimulation. Changes in activity during the stimulus and trace interval were largest in the medial and dorsal MGN divisions on CS+ trials and on trials in which a CR was made. Examination of probe stimuli of short (50 ms) and long (600 ms) duration suggested that both CR latency and activity changes in the trace interval were related to stimulus duration and time-locked to stimulus offset. Comparisons of neural activity on the basis of fast or slow CR responses revealed different patterns of response – activity on fast CR trials was generally greater and tended to occur earlier. These results suggest that MGN neurons are involved in the maintenance of a sensory memory trace and possibly play a part in CR generation and timing.

29 citations


Cites background from "Rapid associative learning: conditi..."

  • ...These two response types probably rely, at least in part on different nervous system substrates; the cerebellum and its deep nuclei are not necessary for heart-rate conditioning (Lavond et al. 1984), while elements of the corticolimbic system are essential (Powell 1994)....

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Journal ArticleDOI
TL;DR: The data suggest that CRM is a function of US intensity and have implications for posttraumatic stress disorder, a disorder potentially modeled by CRM.
Abstract: Conditioning-specific reflex modification (CRM) of the rabbit’s nictitating membrane response (NMR) describes changes in responding to an unconditioned stimulus (US) when the rabbit is tested in the absence of the conditioned stimulus. Specifically, after at least 3 days of tone-electrical stimulation pairings, responses to the US increase in size, especially at intensities weaker than the training intensity. CRM is similar to classical conditioning in that it is a function of the strength of conditioning, it can be extinguished, and it can be generalized from one stimulus to another. To compare CRM and classical conditioning further, we conducted three experiments to examine the effects of US intensity (1.0, 2.0, and 4.0 mA) on CRM. CRM was weak following conditioning with 1.0 mA and extremely strong following conditioning with 2.0 mA and 4.0 mA. The data suggest that CRM is a function of US intensity and have implications for posttraumatic stress disorder, a disorder potentially modeled by CRM.

28 citations

References
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Journal ArticleDOI
TL;DR: It is proposed that these drugs reduce anxiety by impairing the functioning of a widespread neural system including the septo-hippocampal system (SHS), the Papez circuit, the prefrontal cortex, and ascending monoaminergic and cholinergic pathways which innervate these forebrain structures.
Abstract: A model of the neuropsychology of anxiety is proposed. The model is based in the first instance upon an analysis of the behavioural effects of the antianxiety drugs (benzodiazepines, barbiturates, and alcohol) in animals. From such psychopharmacologi-cal experiments the concept of a “behavioural inhibition system” (BIS) has been developed. This system responds to novel stimuli or to those associated with punishment or nonreward by inhibiting ongoing behaviour and increasing arousal and attention to the environment. It is activity in the BIS that constitutes anxiety and that is reduced by antianxiety drugs. The effects of the antianxiety drugs in the brain also suggest hypotheses concerning the neural substrate of anxiety. Although the benzodiazepines and barbiturates facilitate the effects of γ-aminobutyrate, this is insufficient to explain their highly specific behavioural effects. Because of similarities between the behavioural effects of certain lesions and those of the antianxiety drugs, it is proposed that these drugs reduce anxiety by impairing the functioning of a widespread neural system including the septo-hippocampal system (SHS), the Papez circuit, the prefrontal cortex, and ascending monoaminergic and cholinergic pathways which innervate these forebrain structures. Analysis of the functions of this system (based on anatomical, physiological, and behavioural data) suggests that it acts as a comparator: it compares predicted to actual sensory events and activates the outputs of the BIS when there is a mismatch or when the predicted event is aversive. Suggestions are made as to the functions of particular pathways within this overall brain system. The resulting theory is applied to the symptoms and treatment of anxiety in man, its relations to depression, and the personality of individuals who are susceptible to anxiety or depression.

4,725 citations


"Rapid associative learning: conditi..." refers background in this paper

  • ... Gray (1982) has described in detail a behavioral inhibition system that is operative during exposure to signals predicting...

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  • ...Others have also emphasized that parasympathetic mechanisms may play an important role in the early stages of information processing (Lacy & Lacey, 1974; Gray, 1982 )....

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Book
01 Jan 1980
TL;DR: Anatomy of the prefrontal cortex chemical neurotransmission animal neuropsychological neurophysiology human neuropsychology neuroimaging overview of prefrontal functions - the temporal organization of behaviour.
Abstract: Anatomy of the prefrontal cortex chemical neurotransmission animal neuropsychology neurophysiology human neuropsychology neuroimaging overview of prefrontal functions - the temporal organization of behaviour.

2,498 citations

Book
01 Jan 1967

1,193 citations


"Rapid associative learning: conditi..." refers background in this paper

  • ...Such differences have, of course, been known for some time (e.g., see Gantt, 1960; Konorski, 1967 )....

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  • ...Such dif ferences have, of course, been known for some t ime (e.g., see Gantt, 1960; Konorski , 1967)....

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Journal ArticleDOI
TL;DR: AL is an essential link in the circuitry through which auditory stimuli are endowed with affective properties and may function as the sensory interface of the amygdala during emotional learning.
Abstract: Previous work has implicated projections from the acoustic thalamus to the amygdala in the classical conditioning of emotional responses to auditory stimuli. The purpose of the present studies was to determine whether the lateral amygdaloid nucleus (AL), which is a major subcortical target of projections from the acoustic thalamus, might be the sensory interface of the amygdala in emotional conditioning. Lesions were placed in AL of rats and the effects on emotional conditioning were examined. Lesions of AL, but not lesions of the striatum above or the cortex adjacent to the AL, interfered with emotional conditioning. Lesions that only partially destroyed AL or lesions placed too ventrally that completely missed AL had no effect. AL lesions did not affect the responses elicited following nonassociative (random) training. AL is thus an essential link in the circuitry through which auditory stimuli are endowed with affective properties and may function as the sensory interface of the amygdala during emotional learning.

1,086 citations


"Rapid associative learning: conditi..." refers background in this paper

  • ...These findings from our laboratory, as well as those of others (e.g., Kapp & Pascoe, 1986; LeDoux, Cicchetti, Xagoraris, & Romanski, 1990; Schneiderman, McCabe, Haselton, Ellenberger, Jarrell, & Gentile, 1987), strongly suggest different central nervous system substrates for rapidly and slowly acquired response systems....

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  • ...However, LeDoux and coworkers have demonstrated a medial geniculate projection to the lateral nucleus of the amygdala in the rat that projects to both the central nucleus and the basolateral nucleus (Clugnet, LeDoux, & Morrison, 1990; LeDoux et al., 1990; Clugnet & LeDoux, 1990)....

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Journal ArticleDOI
20 Jan 1984-Science
TL;DR: The dentate-interpositus nuclei were concluded to be critically involved in the learning and production of classically conditioned responses.
Abstract: Classical conditioning of the eyelid response in the rabbit was used to investigate the neuronal structures mediating basic associative learning of discrete, adaptive responses. Lesions of the ipsilateral dentate-interpositus nuclei, but not of the cerebellar cortex, abolished the learned eyeblink response. Recordings from these nuclei have revealed neuronal responses related to the learning of the response. Stimulating these recording sites produced the eyelid response. The dentate-interpositus nuclei were concluded to be critically involved in the learning and production of classically conditioned responses.

866 citations


"Rapid associative learning: conditi..." refers background in this paper

  • ...Moreover, the deep nuclei of the cerebellum ( McCormick & Thompson, 1984 ), as well as the cerebellar cortex (Yeo, Hardiman, & Glickstein, 1984), may be necessary for EB conditioning to occur....

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  • ...Moreover, the deep nuclei of the cerebellum (McCormick & Thompson, 1984), as well as the cerebellar cortex (Yeo, Hardiman, & Glickstein, 1984), may be necessary for EB conditioning to occur....

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