Extinction in human learning and memory

In two experiments, participants were given extinction training in a human causal learning task. In both experiments, three critical experimental cues were paired with different outcomes in a first phase of training and were then extinguished in a second phase. Three control cues were given the same treatment in the first phase of training, but were not then presented in the second phase. Participants' ability to correctly identify the outcome with which each cue had been paired in the first phase was lower for extinguished than for control cues. Causal attributions to the extinguished cues were also lower than those to the control cues, a difference that correlated with outcome memory. These data are consistent with the idea that extinction in causal judgement is due, at least in part, to a failure to remember the cue-outcome relationship encoded in the first phase of training.     

Extinction in human learning and memory

In two experiments, participants were given extinction training in a human causal learning task. In both experiments, three critical experimental cues were paired with different outcomes in a first phase of training and were then extinguished in a second phase. Three control cues were given the same treatment in the first phase of training, but were not then presented in the second phase. Participants' ability to correctly identify the outcome with which each cue had been paired in the first phase was lower for extinguished than for control cues. Causal attributions to the extinguished cues were also lower than those to the control cues, a difference that correlated with outcome memory. These data are consistent with the idea that extinction in causal judgement is due, at least in part, to a failure to remember the cue–outcome relationship encoded in the first phase of training.     

Extinction partially reverts structural changes associated with remote fear memory

Structural synaptic changes occur in medial prefrontal cortex circuits during remote memory formation. Whether extinction reverts or further reshapes these circuits is, however, unknown. Here we show that the number and the size of spines were enhanced in anterior cingulate (aCC) and infralimbic (ILC) cortices 36 d following contextual fear conditioning. Upon extinction, aCC spine density returned to baseline, but the enhanced proportion of large spines did not. Differently, ILC spine density remained elevated, but the size of spines decreased dramatically. Thus, extinction partially erases the remote memory network, suggesting that the preserved network properties might sustain reactivation of extinguished conditioned fear.     

Betting on memory leads to metacognitive improvement by younger and older adults

The present study examined how younger and older adults choose to selectively remember important information. Participants studied words paired with point values, and "bet" on whether they could later recall each word. If they bet on and recalled the word, they received the points, but if they failed to recall it, they lost those points. Participants (especially older adults) initially bet on more words than they later recalled, but greatly improved with task experience. The incorporation of rewards and penalties associated with metacognitive predictions, and multiple study-test trials, revealed that both younger and older adults can learn to maximize performance.     

Extinction memory in the crab Chasmagnathus: recovery protocols and effects of multi-trial extinction training

A decline in the frequency or intensity of a conditioned behavior following the withdrawal of the reinforcement is called experimental extinction. However, the experimental manipulation necessary to trigger memory reconsolidation or extinction is to expose the animal to the conditioned stimulus in the absence of reinforcement. Recovery protocols were used to reveal which of these two processes was developed. By using the crab contextual memory model (a visual danger stimulus associated with the training context), we investigated the dynamics of extinction memory in Chasmagnathus. Here, we reveal the presence of three recovery protocols that restore the original memory: the old memory comes back 4 days after the extinction training, or when a weak training is administered later, or once the VDS is presented in a novel context 24 h after the extinction session. Another objective was to evaluate whether the administration of multi-trial extinction training could trigger an extinction memory in Chasmagnathus. The results evince that the extinction memory appears only when the total re-exposure time is around 90 min independently of the number of trials employed to accumulate it. Thus, it is feasible that the mechanisms described for the case of the extinction memory acquired through a single training trial are valid for multi-trial extinction protocols. Finally, these results are in agreement with those reports obtained with models phylogenetically far apart from the crab. Behind this attempt is the idea that in the domain of studies on memory, some principles of behavior organization and basic mechanisms have universal validity.     

Environmental determinants of memory improvement in late adulthood

Two studies were conducted with nursing home residents to determine whether memory could be improved. This was accomplished by increasing the cognitive demand of the environment and then varying the extent to which residents were motivated to attend to and remember these environmental factors. In Study 1, motivation to practice recommended cognitive activities was manipulated by varying the degree of reciprocal self-disclosure offered by interviewers in a series of dyadic interactions. In Study 2, motivation to practice recommended cognitive activities was manipulated by varying whether positive outcomes were contingent on attending to and remembering these activities, which increased in demand over time. Whether as a function of interpersonal (Study 1) or practical (Study 2) incentives, engaging in cognitive activity resulted in improvement on standard short-term memory tests, including probe recall and pattern recall, as well as in improvement on nurses' ratings of alertness, mental activity, and social adjustment for experimental groups relative to controls.     

Hippocampal PKA/CREB pathway is involved in the improvement of memory induced by spermidine in rats

Spermidine (SPD) is an endogenous polyamine that modulates N-methyl-D-aspartate (NMDA) receptor function, and has been reported to facilitate memory formation. In the current study we determined whether or not the PKA/CREB signaling pathway is involved in SPD-induced facilitation of memory of inhibitory avoidance task in adult rats. The post-training administration of the cAMP-dependent protein kinase (PKA) inhibitor, N-[2-bromocinnamylamino)ethyl]-5-isoquinoline sulfonamide [H-89, 0.5 ρmol intrahippocampal (ih)] or the antagonist of the NMDA receptor polyamine-binding site (arcaine, 0.02 nmol ih) with SPD (0.2 nmol ih) prevented memory improvement induced by SPD. Intrahippocampal administration of SPD (0.2 nmol) facilitated PKA and cAMP response element-binding protein (CREB) phosphorylation in the hippocampus 180 min, but not 30 min, after administration, and increased translocation of the catalytic subunit of PKA into the nucleus. Arcaine (0.02 nmol) and H-89 (0.5 ρmol) prevented the stimulatory effect of SPD on PKA and CREB phosphorylation. These results suggest that memory enhancement induced by the ih administration of SPD involves the PKA/CREB pathways in rats.     

Retention of Conditioned Inhibition Produced by Extinction

Rats in a flavor aversion procedure were used to examine the extent to which an extinguished CS can pass a retardation and summation test for conditioned inhibition after either a short or a long retention interval. Rats were given a single pairing of a flavored solution with LiCl, and then received a large number of CS-alone extinction trials. Following extinction, some subjects received a 3-week retention interval following extinction while others did not. Extinction produced evidence of conditioned inhibition on both tests when a short retention interval occurred following extinction. However, conditioned inhibition was attenuated by the long retention interval when assessed with a retardation test, but no effect of the long retention interval was observed when inhibition was evaluated with a summation test.     

Treatment of Infant Sleep Disturbance by Graduated Extinction

Chronic disturbed sleep is a common problem in preschool children. Treatment by extinction is successful but may be accompanied by side-effects such as post-extinction response bursts which make the treatment aversive to parents and which impairs their compliance. This study evaluated a modified procedure, graduated extinction, which required parents gradually to reduce attention to bedtime disturbance and night waking from average baseline levels to zero over 28 days. Baseline measures of frequency and duration of night waking, sleep-onset latency, and bedtime delay were made for six children (6- to 14-months-old). Parents were then instructed to use graduated extinction using a multiple-baseline-across-subjects design. Following treatment, three out of six children showed clinically significant reductions in the frequency and duration of night waking, and a fourth child substantially reduced the duration of her wakings. These gains were maintained at followup. Lack of improvement was associated with parental noncompliance with treatment and childhood illness. Two subjects showed some evidence of post-extinction response bursts despite the gradual withdrawal of parental attention. Parents reported high satisfaction with the procedures but half found the procedure mildly to moderately stressful. While graduated extinction was an effective treatment, regular extinction offers practical and clinical advantages in most cases.     

Extinction can be enhanced by a concurrent excitor

Five experiments used rat subjects to investigate the impact on extinction of the presence of other conditioned stimuli. In Experiments 1 (Pavlovian magazine approach) and 2 (instrumental discriminative training), an excitatory stimulus (X) was extinguished alone, in conjunction with a previously reinforced other stimulus (A), in conjunction with previously nonreinforced other stimulus (B), or it was spared extinction. Responding during extinction was greatest to AX, and subsequent testing of X alone showed AX extinction to have produced the most decrement to X. Experiment 3 found similar results using a within-subject design. Experiment 5 continued separate reinforced presentations of A during extinction. This procedure not only promoted extinction of X but also converted it into a conditioned inhibitor. These experiments bear on the mechanisms of overshadowing and stimulus processing, as well as provide information on the determinants of extinction.     

Facilitation of Extinction of Conditioned Fear by D-Cycloserine

Abstract— Excessive fear and anxiety are characteristic of disorders such as post-traumatic stress disorder (PTSD) and phobias and are believed to reflect abnormalities in neural systems governing the development and reduction of conditioned fear. Conditioned fear can be suppressed through a process known as extinction, in which repeated exposure to a feared stimulus in the absence of an aversive event leads to a gradual reduction in the fear response to that stimulus. Like conditioned fear learning, extinction is dependent on a particular protein (the N-methyl-D-aspartate or NMDA receptor) in a part of the brain called the amygdala. Blockade of this receptor blocks extinction and improving the activity of this receptor with a drug called D-cycloserine speeds up extinction in rats. Because exposure-based psychotherapy for fear disorders in humans resembles extinction in several respects, we investigated whether D-cycloserine might facilitate the loss of fear in human patients. Consistent with findings from the animal laboratory, patients receiving D-cycloserine benefited more from exposure-based psychotherapy than did placebo-treated controls. Although very preliminary, these data provide initial support for the use of cognitive enhancers in psychotherapy and demonstrate that preclinical studies in rodents can have direct benefits to humans.     

Conditioned Inhibition Produced by Extinction of a Conditioned Stimulus

Four experiments used a conditioned taste aversion procedure to examine the potential for CS-alone extinction treatment to produce a conditioned stimulus that possesses inhibitory properties. In Experiment 1, saccharin was paired with LiCl, and then saccharin was presented alone for several trials to produce extensive behavioral extinction. Animals receiving this treatment were retarded in reacquiring conditioned responding to saccharin relative to control subjects receiving conditioning to the flavor for the first time. In Experiment 2, the extinguished saccharin stimulus was shown to decrease conditioned responding to a known excitor when the two stimuli were presented in compound as a summation test. Experiments 3A and 3B replicated the findings of Experiments 1 and 2 while providing evidence that the effects were not due to the differential effects of neophobia during testing. These three experiments revealed that an extinguished conditioned excitor passes retardation and summation tests for conditioned inhibition. Experiment 4 found that extinction of a known excitor was slowed when the excitor was extinguished in compound with a previously extinguished conditioned stimulus. That is, an extinguished CS provided protection from extinction to another CS, a finding also consistent with the view that extinction produces conditioned inhibition.     

On the Massness of Mass Extinction

Philosophia - The central question in this paper is whether anthropogenic mass extinction is ethically problematic above and beyond the sum of extinctions involved. The point of asking this...     

Comparison of metabolic rates, language, and memory in subcortical aphasias

Four patients with subcortical lesions and either aphasia or amnesia were compared to four patients with cortical lesions and aphasia. Each patient had [18F] fluorodeoxyglucose positron-emission computed tomography, language, and memory evaluations. Marked metabolic depression was found in the thalamus and caudate in all patients. The subcortical patients had only mild left-cortical changes, while the cortical patients showed marked cortical metabolic changes in the left hemisphere. Language changes were mild in the subcortical patients, while moderate to severe in the cortical patients. All patients showed severe verbal memory dysfunction. The only common abnormalities in the two groups were metabolic changes in the thalamus and severity of verbal memory dysfunction. These findings suggest a relationship between verbal memory and thalamic function.     

Some Differences in Extinction by Normal and Whole-Body Irradiated Monkeys

Abstract

Blanchard, P. The Child and Society: An Introduction to the Social Psychology of the Child. New York: Longmans, Green, 1928. Pp. ix + 369. $2.25.

Cobb, S. The New Leaven: Progressive Education and Its Effect upon the Child and Society. New York: John Day, 1928. Pp. x + 340.

Jones, R. M. New Studies in Mystical Religion. New York: Macmillan, 1927. Pp. 205. $1.75.

Woodburne, A. S. (Introduction by Shailer Mathews.) The Religious Attitude. New York: Macmillan, 1927. Pp. vi+353. $2.50.

Holzinger, K. J. Statistical Methods for Students in Education. Boston: Ginn, 1928. Pp. viii + 372. $3.60.

Hartshorne, H. and May, M. A. Studies in Deceit. New York: Macmillan, 1928. Bk. I, pp xxi+414; Bk. II, pp. viii+306. $4.50.

Claremont, C. A. Intelligence and Mental Growth. New York: Norton, 1928. Pp. 120. $1.00.

Malinowski, B. Myth in Primitive Psychology. New York: Norton, 1926. Pp. ix+94. $1.00.

Malinowski, B. The Father in Primitive Psychology. New York: Norton, 1927. Pp. 95. $1.00.

Miller, E. Types of Mind and Body. New York: Norton, 1927. Pp. 95. $1.00.

Warden, C. J. A Short Outline of Comparative Psychology. New York: Norton, 1927. Pp. xii+96. $1.00.

Wheeler, W. M. Emergent Evolution and the Development of Societies. New York: Norton, 1928. Pp. vii+80. $1.00.     

Heterogeneity in memory training improvement among older adults: A latent class analysis

This study investigated the extent to which older adults' associative memory functioning can be modified through instruction and practice based on individuals' memory status. Here 42 younger adults and 42 older adults performed four tasks that measured strategic and binding aspects of memory. With latent class analysis, two classes of older adults were identified. The first class showed higher memory functioning similar to younger adults, while the second class was characterised by lower memory functioning. A subsequent analysis examined whether the high- and low-performing older adults differ in patterns of gain from receiving instruction and practice on a mnemonic strategy. The results revealed that high-performing older adults, similar to younger adults, showed higher associative memory performance under explicit intentional encoding instruction and after extensive practice of the strategy. In contrast, low-performing older adults benefited more from directed instruction of the strategy. The results are discussed in relation to individual differences in the functional status of mechanisms underlying memory functioning, and how these differences may lead to compensation or magnification of training gain. The present findings highlight the importance of considering differential memory processes to develop specific training paradigms that target the processes that show the most prominent decline.     

Extinction of the context and latent inhibition

The hypothesis that latent inhibition could be reduced by extinguishing the experimental context, that is, exposing the rats to the context between exposure to the conditional stimulus (CS) and conditioning, was tested. All experiments used the conditioned emotional response procedure. In Experiment 1, extinction was not effective when the animals were exposed to the clicker 40 times off the baseline of responding for food and when the clicker CS was partially reinforced with shocks during the test phase. In Experiments 2 and 3, latent inhibition could be reduced by extinction if the animals were exposed to the CS 24 or 16 times on-baseline, and if continuous reinforcement was used during the test. In Experiments 4, 5, and 6, we attempted to determine which variable was responsible for the discrepant results. In Experiment 4, extinction was effective with 20 or 40 on-baseline exposures to the CS, using continuous reinforcement during the test. In Experiment 5, extinction was not effective with exposure on- or off-baseline, using 24 exposures and partial reinforcement. Finally, in Experiment 6, extinction reduced latent inhibition using continuous, but not partial, reinforcement with 40 exposures off-baseline. From these results, we concluded that Wagner's model of habituation was not sufficient to account for latent inhibition and that a hybrid model, using both associative and cognitive representational processes, was necessary.     

Heterogeneity in memory training improvement among older adults: A latent class analysis

This study investigated the extent to which older adults' associative memory functioning can be modified through instruction and practice based on individuals' memory status. Here 42 younger adults and 42 older adults performed four tasks that measured strategic and binding aspects of memory. With latent class analysis, two classes of older adults were identified. The first class showed higher memory functioning similar to younger adults, while the second class was characterised by lower memory functioning. A subsequent analysis examined whether the high- and low-performing older adults differ in patterns of gain from receiving instruction and practice on a mnemonic strategy. The results revealed that high-performing older adults, similar to younger adults, showed higher associative memory performance under explicit intentional encoding instruction and after extensive practice of the strategy. In contrast, low-performing older adults benefited more from directed instruction of the strategy. The results are discussed in relation to individual differences in the functional status of mechanisms underlying memory functioning, and how these differences may lead to compensation or magnification of training gain. The present findings highlight the importance of considering differential memory processes to develop specific training paradigms that target the processes that show the most prominent decline.