A mutation in the AMPA-type glutamate receptor, glr-1, blocks olfactory associative and nonassociative learning in Caenorhabditis elegans.

The α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-type ionotropic glutamate receptor mediates fast excitatory neurotransmission in the vertebrate brain and is important for synaptic plasticity and the initial induction of long-term potentiation (LTP). This study found that the putative Caenorhabditis elegans AMPA receptor gene, glr-1, plays a significant role in experience-dependent behavior in C. elegans. glr-1 mutants are deficient in an olfactory associative learning task, in which diacetyl (DA) is paired with acetic acid solution. glr-1 mutant nematodes are also impaired in nonassociative learning (habituation) with the same DA stimulus. The C. elegans learning mutants, lrn-1 and lrn-2, are impaired in chemosensory associative learning yet have no deficits in habituation. The results suggest that although associative and nonassociative learning can be genetically dissociated ( lrn-1 and lrn-2), they also share some common molecular processes, including glr-1 -mediated neurotransmission. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context conditioning in habituation in the nematode Caenorhabditis elegans.

Habituation has traditionally been considered a nonassociative form of learning. However, recent research suggests that retention of this nonassociative form of learning may be aided by associations formed during training. An example of this is context conditioning, in which animals that are trained and tested in the presence of a contextual cue show greater retention than animals trained and tested in different environments. This article reports context conditioning in habituation in the nematode Caenorhabditis elegans. The results showed that retention of habituation to tap at both 10- and 60-s interstimulus intervals was significantly greater if training and testing occurred in the presence of the same chemosensory cue (NaCH?COO). This context conditioning showed both extinction and latent inhibition, demonstrating that these simple worms with only 302 neurons are capable of associative context conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tap withdrawal circuit interneurons require CREB for long-term habituation in Caenorhabditis elegans.

We investigated the role of the Caenorhabditis elegans CREB (cAMP response element binding protein) homologue, crh-1, in response to tap (nonlocalized mechanosensory stimulation) and tap habituation. Worms with a loss-of-function mutation in crh-1 performed smaller reversals in response to tap than did wild-type worms and did not show long-term memory for spaced training 24-hr posttraining; however, they did show short-term habituation to tap stimuli when stimuli were presented at both 10-s and 60-s interstimulus intervals, and showed 12-hr intermediate memory for spaced habituation training (intermediate-term memory). Expressing CRH-1 broadly throughout the nervous system and in a subset of interneurons of the tap withdrawal circuit, but not in the mechanosensory neurons, rescued the long-term memory defects observed in crh-1 mutants. Here we show for the first time that CREB is required for long-term habituation and show that the interneurons of the tap withdrawal response circuit are the locus of plasticity for long-term mechanosensory habituation in C. elegans. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Olfactory associative learning in Caenorhabditis elegans is impaired in lrn-1 and lrn-2 mutants.

The C. elegans mutants, lrn-1 and lrn-2, are impaired in associative learning using conditioned taste cues. Both mutants are defective in associative learning about appetitive and aversive events, indicating that lrn-1 and lrn-2 exert effects across motivational boundaries. In a new olfactory associative learning paradigm, in which wild type worms learn to avoid a previously attractive diacetyl odor after it has been paired with an aversive acetic acid solution, lrn-1 and lrn-2 are impaired. Although defective in associative learning using a conditioned olfactory cue, nonassociative learning (habituation and dishabituation) using this same olfactory cue is unaffected. The discovery that lrn-1 and lrn-2 are defective in associative learning with both taste and olfactory cues may suggest that associative learning in different sensory modalities converges on a common genetic pathway in C. elegans that is subserved by lrn-1 and lrn-2. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovery from habituation in Caenorhabditis elegans is dependent on interstimulus interval and not habituation kinetics.

The habituation of the tap withdrawal reflex of Caenorhabditis elegans was assessed to determine whether the kinetics of recovery from habituation were dependent on the interstimulus interval (ISI) uscd during habituation training or alternately, on the rate and asymptotic level of habituation produced at a given ISI. Two groups of intact animals were trained at either a 10-s (CON10) or a 60-s (CON60) ISI Laser ablation was used to alter the habituation kinetics in one further group of animals (PLM10) independent of ISI. Although the PLM10 animals trained at a 10-s ISI habituated like CON60 worms the recovery from habituation of the PLM10 animals very closely resembled the recovery of the CON10 worms. Thus recovery kinetics are dictated by consequences of a given ISI which do not impact upon habituation rate and asymptote. This suggests the recruitment of multiple ISI-dependent processes during habituation in C. elegans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recall in normals and subnormals of like mental age.

Normal children and young adult imbeciles were matched for mental age and were given sets of 6 pairs of words to learn by association. The words were recorded on tape, and presented to subgroups at a sound intensity of 90 db. or 55 db. Each subgroup was further subdivided—? the Ss being given 10 and ? given 20 repetitions. 1 minute, 2 days, and 1 month later they heard the stimulus word of each pair and were asked to give the appropriate response word. It was shown that there was no difference in learning or memory scores between normals and imbeciles. Frequency of presentation affected immediate recall scores of both groups, with intensity level contributing to a lesser degree. Memory over longer time intervals was determined by the amount initially learned, rather than by the conditions under which such learning had occurred. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How Many Dimensions Underlie Judgments of Learning and Recall? Evidence From State-Trace Methodology.

The authors used state-trace methodology to investigate whether a single dimension (e.g., strength) is sufficient to account for recall and judgments of learning (JOLs) or whether multiple dimensions (e.g., intrinsic and extrinsic factors) are needed. The authors separately manipulated the independent variables of intrinsic and extrinsic cues, determining their state traces for recall and JOLs. In contrast to the supposition that intrinsic cues have similar effects on both recall and JOLs whereas extrinsic cues affect JOLs less strongly than recall (i.e., 2 dimensions underlying recall and JOLs), the authors found repeated support for the sufficiency of a single dimension for both recall and JOLs (not only immediate JOLs but also delayed JOLs) across a variety of intrinsic and extrinsic cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning, prediction, and readability.

One group of Ss, after memorization practice, learned as much as they could in set study periods (recording recall immediately at period end). Another group predicted each successive word from a knowledge of preceding context, for 30 English passages. Recall and prediction scores were correlated with Flesch and Dale-Chall readability scores. all the correlations were positive and high. Both readability formulas showed a higher correlation with learning than with prediction, but the difference was not significant. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic architecture of learning and delayed recall: A twin study of episodic memory.

Objective: Although episodic memory is often conceptualized as consisting of multiple component processes, there is a lack of understanding as to whether these processes are influenced by the same or different genetic determinants. The aim of the present study was to utilize multivariate twin analyses to elucidate the degree to which learning and delayed recall, two critical measures of episodic memory performance, have common or different genetic and environmental influences. Method: Participants from the Vietnam Era Twin Study of Aging (314 monozygotic twin pairs, 259 dizygotic twin pairs, and 47 unpaired twins) were assessed using the second edition of the California Verbal Learning Test. Mean age at the time of the evaluation was 55.4 years (SD = 2.5). Results: Model fitting revealed the presence of a higher-order latent factor influencing learning, short- and long-delay free recall, with a heritability of .36. The best-fitting model also indicated specific genetic influences on learning, which accounted for 10% of the overall variance. Given that learning involves the acquisition and retrieval of information, whereas delayed recall involves only retrieval, we conclude that these specific effects are likely to reflect genes that are specific to acquisition processes. Conclusion: These results demonstrate that even in nonclinical populations, it is possible to differentiate component processes in episodic memory. These different genetic influences may have implications for gene association studies, as well as other genetic studies of cognitive aging and disorders of episodic memory such as Alzheimer's disease or mild cognitive impairment. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Review of Social Learning and Clinical Psychology.

Reviews the book "Social learning and clinical psychology," by Julian B. Rotter (see record 2005-06617-000). The stated purpose of this book is to arrive at a systematic theory from which may be drawn specific principles for actual clinical practice, and to illustrate some of the more important applications of the theory to the practice. The first three chapters represent for the most part a clear and incisive introduction to the major purpose of the book, chapters which can be read with profit by all clinical psychologists. The next four chapters, which represent the bulk of the book, contain the aims and concepts of Rotter's social learning position as well as the ways in which it differs from other approaches. Rotter's discussion and evaluation of psychoanalytic theory is amazingly superficial and, to the unwary graduate student, misleading. First, it represents one of the few attempts to formulate and apply a learning theory to clinical phenomena and problems-the more such courageous attempts we have, the better will we be able to evaluate the adequacy of such theories. Second, Rotter's formulations have generated a relatively large number of studies at The Ohio State University-a tribute not only to Rotter's effectiveness as a teacher but a reflection of the fruitfulness of the formulations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning of nondomain facts in high- and low-knowledge domains.

Research on expertise has repeatedly documented that experts learn new information better than do novices, but only when the information is relevant to the expert's domain. It was found in Experiment 1 that participants showed superior learning and recall of a large quantity of new, non-domain-relevant facts about concepts within their domain of high knowledge than about concepts for which they had low domain knowledge. Experiment 2 investigated whether the participants' superior recall of new facts related to concepts within their domain of high knowledge was due to the number of prior facts associated with the concept or to the prior frequency of repetition of those concepts. It was found that participants' recall of new facts was better for concepts with 5 prior associated facts than for concepts with a single prior association but that the number of previous repetitions of each concept did not affect the level of recall for the new facts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Learning and behavior: A contemporary synthesis.

Reviews the book, Learning and behavior: A contemporary synthesis by Mark E. Bouton (see record 2006-21409-000). The reviewer praises the author for creating a student-friendly textbook for an undergraduate course in animal learning that is both comprehensive and current. Bouton presents the major theoretical issues and findings in their historical context. Chapter topics include: (1) adaptation; (2) Pavlovian conditioning; (3) operant conditioning; (4) choice behavior; (5) theories of reinforcement; (6) motivation; (7) cognition; (8) spatial learning; (9) learned helplessness; and (10) superstitious behavior. Bouton comes full circle in the final section, "A cognitive analysis of instrumental action," by describing experimental evidence for the existence of various types of associations (i.e., S-S*, R-S*) that were introduced in the first chapter. The reviewer believes students and instructors alike will enjoy this very readable book. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of tap withdrawal response habituation on other withdrawal behaviors: The localization of habituation in the nematode Caenorhabditis elegans.

Four experiments were conducted to identify the possible loci of habituation of the nematode tap withdrawal response (TWR) by charactering the effects of TWR habituation on other nonmechanosensory withdrawal behaviors that are mediated by overlapping sets of neurons. Experiments 1–2 established behavioral and anatomical relationships between spontaneous and tap-induced backward locomotion in the worm. Experiment 3 demonstrated that habituation of the TWR affected neither the magnitude nor frequency of spontaneous reversal activity. Experiment 4 extended this result to an evoked response: Habituation of the TWR had no effect on reversals evoked by a thermal stimulus. These studies, which show that the loci of change associated with habituation of the TWR are presynaptic to the interneurons and motor neurons that control locomotion, probably distributed among the mechanosensory neurons, illustrate that a complete understanding of plasticity requires a knowledge of both the anatomical and molecular substrates of change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Perceptual Learning and Adaptation.

Reviews the book, Perceptual Learning and Adaptation by P. C. Dodwell (ed.). This is an inexpensive collection of outstanding basic articles on the relation of experience and perception for comparative, cognitive, and developmental psychology. A well planned selection of readings but rather too specialized for many general students of psychology. Good visual materials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation Between Judgments and Outcome-Expectancy Measures in Covariation Learning: A Signal Detection Theory Approach.

A number of studies using trial-by-trial learning tasks have shown that judgments of covariation between a cue c and an outcome o deviate from normative metrics. Parameters based on trial-by-trial predictions were estimated from signal detection theory (SDT) in a standard causal learning task. Results showed that manipulations of P(c) when contingency (ΔP) was held constant did not affect participants' ability to predict the appearance of the outcome (d') but had a significant effect on response criterion (c) and numerical causal judgments. The association between criterion c and judgment was further demonstrated in 2 experiments in which the criterion was directly manipulated by linking payoffs to the predictive responses made by learners. In all cases, the more liberal the criterion c was, the higher judgments were. The results imply that the mechanisms underlying the elaboration of judgments and those involved in the elaboration of predictive responses are partially dissociable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Source Recall Enhances Children's Discrimination of Seen and Heard Events.

The effects of rehearsing actions by source (slideshow vs. story) and of test modality (picture vs. verbal) on source monitoring were examined. Seven- to 8-year-old children (N = 30) saw a slideshow event and heard a story about a similar event. One to 2 days later, they recalled the events by source (source recall), recalled the events without reference to source (no-source-cue recall), or engaged in no recall. Seven to 8 days later, all children received verbal and picture source-monitoring tests. Children in the source recall group were less likely than children in the other groups to claim they saw actions merely heard in the story. No-source-cue recall impaired source identification of story actions. The picture test enhanced recognition, but not source monitoring, of slide actions. Increasing the distinctiveness of the target events (Experiment 2) allowed the picture test to facilitate slideshow action discrimination by children in the no-recall group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Call Usage Learning in Gray Seals (Halichoerus grypus).

Call usage learning can be demonstrated on 4 different levels: signaling on command, signaling and refraining from signaling on command, responding to a trained stimulus with a signal from a specific signal class, and responding to the playback of any untrained stimulus with one from the same signal class. Two young gray seals (Halichoerus grypus) were trained successfully to demonstrate the first 2 levels. They also learned to respond to 9 moan stimuli and 9 growl stimuli with vocalizations of the same class (Level 3). However, novel moan and growl stimuli tended to elicit growls. This casts doubt on the possibility that gray seals can reach the 4th level, but it demonstrates that they are capable of the first 3 levels of usage learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning in flatworms and annelids.

This article attempts an exhaustive review of the research purporting to demonstrate behavioral modifications in earthworms, planaria, and related organisms. Studies are grouped first according to phylum, and for each of the phyla considered according to certain subcategories of learning: habituation, classical conditioning, instrumental learning, and variability. Examination of the literature reveals that whereas earlier work was often ill-controlled, more recent research has for the most part been rigorous and convincing. It is concluded that learning and related phenomena have indeed been demonstrated clearly in each of these 2 phyla, and that research on these animals provides a promising means of investigating the "molecular" basis of learning. (74 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chunk Limits and Length Limits in Immediate Recall: A Reconciliation.

Whereas some research on immediate recall of verbal lists has suggested that it is limited by the number of chunks that can be recalled (e.g., N. Cowan, Z. Chen, & J. N. Rouder, 2004; E. Tulving & J. E. Patkau, 1962), other research has suggested that it is limited by the length of the material to be recalled (e.g., A. D. Baddeley, N. Thomson, & M. Buchanan, 1975). The authors investigated this question by teaching new paired associations between words to create 2-word chunks. The results suggest that both chunk capacity limits and length limits come into play. For the free recall of 12-word lists, 6 pre-learned pairs could be recalled about as well as 6 pre-exposed singletons, suggesting a chunk limit. However, for the serially ordered recall of 8-word lists, 4 pre-learned pairs could be recalled about as well as 8 pre-exposed singletons, suggesting a length limit. Other conditions yielded intermediate results suggesting that sometimes both limits may operate together. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of The dissociative mind.

Reviews the book, The dissociative mind by Elizabeth F. Howell (see record 2005-14945-000). In her book, The Dissociative Mind, Elizabeth Howell presents a complex and thorough overview of what she describes as a "sea change" in psychoanalytic theory. From her vantage point as both psychoanalyst and traumatologist, she demonstrates how, in the last 15-20 years, relational trauma and the resulting impact on the individual mind-namely the splits and fissures that comprise dissociation- have made their way back into psychoanalytic thinking. Howell's elaboration of the overwhelmed, traumatized mind is very useful in clients who present with problems in thinking or who have limited capacity to symbolize. However, detailed clinical material of how an analyst thinking of dissociated self states would work with such a client, what Bromberg termed the "relational bridge," would support her fundamental assertions more effectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)