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PubMed2003

Experience-dependent affective learning and risk for psychopathology in children.

The influence of childhood affective experiences across development may be understood in terms of preparedness to learn about emotion, combined with general immaturity and neuro-plasticity of perceptual systems. Early in development, processing resources are relatively immature and limited in capacity, thereby constraining how much information the young child can absorb. But it is clear that learning about emotions proceeds swiftly in nearly all children, suggesting biological preparedness to track associations between certain stimuli and outcomes. It is proposed here that limited processing capacity, in tandem with dispositions to filter or select key privileged stimuli in the environment, facilitates adaptive, rapid, affective learning. The developmental organization of affective systems is contingent upon those features of input that are most learnable, such as signals that are particularly salient, frequent, or predictable. Therefore, plasticity confers risk for maladaptation in that children's learning will be based upon these prominent features of the environment, however aberrant.

Affect↗
PubMed1993

Intertrial responses in defensive instrumental learning.

Data by the author, as well as from other laboratories, show residual fear as the main source of intertrial responses (ITR) during defensive instrumental training in rats, cats and dogs. Between-subject differences in ITR rate arise in the course of training. The differences depend on training conditions and on subject's emotionality. Under the same conditions higher ITR rates correspond to more rapid avoidance learning. The increase of ITR rate is regularly observed in the following circumstances: at early stages of training, after transfer to a less salient discriminative stimulus, and after a change of the task requirements. The decrease of ITR rate corresponds to the plateau level of avoidance or escape performance. Both a lower ITR rate and reduced flexibility of behavior are found after lesions of the amygdala nuclei.

Aggression↗
PubMed1998

Associative mediational processes in the acquired equivalence and distinctiveness of cues.

Three experiments used rats to examine the acquired equivalence or distinctiveness of cues occurring when 2 auditory and 2 visual stimuli were associated with either the same or with different reinforcing outcomes (A1+, A2+, V1*, and V2* vs. A1+, A2*, V1+, and V2*). Subsequent single modality discrimination learning (e.g., A1+, A2-) was assessed in Experiment 1, whereas in Experiment 2, visual and auditory discriminations were tested concurrently (i.e., A1+, A2-, V1-, V2*). In Experiment 3, auditory and visual discriminations (A1+, A2-, V1-, V2*) were trained and then reversed, using either the same (A1-, A2+, V1*, V2-) or different outcomes (A1-, A2*, V1+, V2-) within each stimulus modality. Discriminations were learned more rapidly in these studies when different outcomes were associated with stimuli from the same modality. These results challenge associative mediational theories of acquired equivalence and distinctiveness.

Animals↗
PubMed1999

Rats show unimpaired learning within minutes after recovery from single bolus propofol anesthesia.

PURPOSE: To examine the learning ability of rats shortly after recovery from a bolus dose of propofol by assessing learning on a swim-to-platform task. Also, muscarinic blockade was used as a pharmacological test of whether learning shortly after propofol anesthesia resembles normal learning. METHODS: Propofol anesthetized rats (15-20 mg x kg(-1) i.v.) were trained on a swim-to-platform task five to seven minutes after recovering from surgical anesthesia and tested two to three hours later In addition, the muscarinic antagonist scopolamine hydrobromide (5 mg x kg(-1) s.c.) was given to a subgroup of rats before testing. During 10 trials, the number of times a given rat took 10 sec or longer to locate and climb onto a visible platform was tabulated and counted as errors. RESULTS: When trained shortly after recovery from the anesthetic, propofol anesthetized rats made 3.2 +/- 0.4 compared with 1.0 +/- 0.1 errors in controls (P < 0.0001). Two to three hours later both groups performed equally well. Rats trained after propofol anesthesia and given scopolamine before testing made 0.7 +/- 0.5 errors and performed as well as normal controls, 1.2 +/- 0.2 errors when subjected to the same procedures without propofol anesthesia, and better than scopolamine-treated untrained rats, 5.5 +/- 0.7 errors, (P < 0.05). CONCLUSION: Training five to seven minutes after recovery from propofol anesthesia resulted in normal retention of the swim- to-platform task. It also produced the same resistance to the disruptive effects of scopolamine as did training in rats that were not anesthetized. Thus, the ability to learn recovers rapidly after propofol anesthesia induced by a single intravenous bolus dose.

Anesthesia Recovery Period↗
PubMed2003

Olfactory discrimination learning deficit in heterozygous reeler mice.

Adult mice heterozygous for the 'reeler' mutation (HR mice) have been found not to have a reeler phenotype but to express a number of abnormal traits including reduced sensorimotor gating, lower density of dendritic spines in frontoparietal cortex and hippocampus, and selectively decreased expression of one form of glutamic acid decarboxylase (GAD67). Since reelin is expressed in olfactory areas of the adult mouse brain, we have tested for olfactory functions in HR mice that express only half of the reelin found in wild-type (WT) mice. HR and WT mice were trained to criterion performance of 90% correct in a block of 20 trials on eight distinct simultaneous-cue, two-odor discriminations. HR mice required significantly more training sessions and made more errors than did WT mice in acquiring the first olfactory discrimination. Subsequent discriminations were learned equally rapidly by both HR and WT mice. Memory retention for the final discrimination was tested 1 week after training and was equally good for both groups. Both HR and WT mice showed equivalent sensitivity in discriminating low concentrations of either ethyl acetate or butanol from non-odorized air. Whether or not the olfactory learning deficit observed in HR mice is related to the low dendritic spine density or GAD67 reduction observed in hippocampus and cortex are currently under investigation.

Animals↗
PubMed2007

Is there a tipping point in neuronal ensembles during learning?

Learning is important for humans and can be disrupted by disease. However, the essence of how learning may be represented within a neuronal network is still elusive. Spike trains generated by neurons have been demonstrated to carry information which is relevant for learning. The present study uses well-established mutual information (MI) analysis techniques to better understand learning within neuronal ensembles. Spike trains in tetrode recordings from the dorso-lateral striatum were used for computing MI as rats learnt a T-maze procedural task. We demonstrate that in in-vivo recordings the growth of MI is reflected in the behavioral response as learning proceeds. These changes in MI are seen to correspond to three phases, a low MI value, namely early learning, a rapid increase in MI value, task-acquisition and stabilization of MI, over-training. Over multiple training sessions, small changes in MI within the neuronal network suddenly produce a big change in ensemble MI during the task acquisition phase. This phase represents the "tipping point" in the neuronal network where the MI growth builds habits during motor learning in the striatum.

Action Potentials↗
PubMed1997

Total quality management issues in managed care.

The implementation of total quality management (TQM) in health care has gone on in parallel with the growth of managed care. What is the interaction between the two? Key issues are the ascendance of cost control over quality in many areas, erosion of employee commitment and loyalty, and a short-run orientation. Associated with this is an emphasis on organizational learning rather than learning by autonomous professionals. Both TQM and managed care acknowledge the dynamic nature of clinical processes and the ability and responsibility of both institutions and clinicians to improve their processes. Both are consistent with efforts to identify and implement best practices. However, these similarities should not mask fundamental differences. Continuous improvement must shift its focus from avoiding unnecessary variation to facilitating rapid organizational learning and institutionalizing mass customization into the delivery of health services.

Humans↗
PubMed1999

Phonological recoding and orthographic learning: A direct test of the self-teaching hypothesis.

According to the self-teaching hypothesis (Share, 1995), word-specific orthographic representations are acquired primarily as a result of the self-teaching opportunities provided by the phonological recoding of novel letter strings. This hypothesis was tested by asking normal second graders to read aloud short texts containing embedded pseudoword targets. Three days later, target spellings were correctly identified more often, named more quickly, and spelled more accurately than alternate homophonic spellings. Experiment 2 examined whether this rapid orthographic learning can be attributed to mere visual exposure to target strings. It was found that viewing the target letter strings under conditions designed to minimize phonological processing significantly attenuated orthographic learning. Experiment 3 went on to show that this reduced orthographic learning was not attributable to alternative nonphonological factors (brief exposure durations or decontextualized presentation). The results of a fourth experiment suggested that the contribution of pure visual exposure to orthographic learning is marginal. It was concluded that phonological recoding is critical to the acquisition of word-specific orthographic representations as proposed by the self-teaching hypothesis.

Child↗
PubMed1985

Cyclophosphamide in the male rat: behavioral effects in the adult offspring.

Cyclophosphamide in a daily dose of 10 mg/kg was injected intraperitoneally in male Wistar rats for 15 days. Two rats each time were killed for testis examination at regular intervals within 100 days following treatment (over 2 spermatogenetic cycles). One hundred days after the end of the treatment, the other rats, whose spermatogenesis had recovered in the meantime, were mated with 3-month-old females. Offspring were evaluated in regard to the mean number per litter, sex ratio, frequency of gross external malformations, growth pattern, mortality in the first 4 months of life and reproductive ability at 6 months of age. Offspring behavior was also examined between 10 and 14 weeks of age. They were evaluated for spontaneous activity and emotionality with an open field test and for learning ability with an avoidance conditioning test. Cyclophosphamide induced a significant decrease in the number of primary spermatocytes and spermatozoa. Only learning ability was altered in the offspring from the treated males, for the animals which succeeded in the avoidance conditioning test did not learn as rapidly as the controls. However, the difference was significant only in the males. Behavioral abnormalities and the possible genetic factors involved are related to the particular concept of 'physioteratogenesis'.

Animals↗
PubMedDate not supplied

Cognitive processes and cognitive progresses as didactic tools in psychiatry.

The authors expose the characteristics of two methods about the teaching and the learning of Psychiatry. Hermeneutic method is based on the model: "this want to say that". It gives rise to rapid and diffused learning which are rarely personalized and it attributes activity to the teacher and passivity to the pupil. "Conjectural" method is based on the model: "this is one of the aspects of a polymer of significances that we may point out as probable conjecture and not as truth". It produces learning less rapid, less diffused but more personal. It attributes activity and passivity as to the teacher as to the pupil. The first method tends to provoke pathological dependence as proselitism and/or contest so the pupil difficulty may assume the heritage of the teacher by having idealized or killed him. The second method tends to form self-governing pupils able to break away from the teacher after having learned from him new knowledges which they use in a personal way.

Humans↗
PubMed1999

Learning categories at different hierarchical levels: a comparison of category learning models.

Three formal models of category learning, the rational model (Anderson, 1990), the configural-cue model (Gluck & Bower, 1988a), and ALCOVE (Kruschke, 1992), were evaluated on their ability to account for differential learning of hierarchically structured categories. An experiment using a theoretically challenging category structure developed by Lassaline, Wisniewski, and Medin (1992) is reported. Subjects learned one of two different category structures. For one structure, diagnostic information was present along a single dimension (1-D). For the other structure, diagnostic information was distributed across four dimensions (4-D). Subjects learned these categories at a general or at a specific level of abstraction. For the 1-D structure, specific-level categories were learned more rapidly than general-level categories. For the 4-D structure, the opposite result was observed. These results proved highly diagnostic for evaluating the models--although ALCOVE provided a good account of the observed results, the rational model and the configural-cue model did not.

Analysis of Variance↗
PubMed2004

The emerging lexicon of children with phonological delays: phonotactic constraints and probability in acquisition.

The effects of phonotactic constraints (i.e., the status of a sound as correctly or incorrectly articulated) and phonotactic probability (i.e., the likelihood of a sound sequence) on lexical acquisition have been investigated independently. This study investigated the interactive influence of phonotactic constraints and phonotactic probability on lexical acquisition in 3 groups of children: children with functional phonological delays (PD), phonology-matched, younger, typically developing children (PM), and age-/vocabulary-matched typically developing peers (AVM). Sixty-eight children participated in a multitrial word-learning task involving nonwords varying in phonotactic constraints (IN vs. OUT) and phonotactic probability (common vs. rare). Correct and error responses were analyzed. Results indicated that OUT sound sequences were learned more rapidly than IN sound sequences. This suggests that OUT sounds may be salient because they represent only a small subset of the child's sound system. The effect of phonotactic probability varied across groups: Children with PD showed a common sound sequence disadvantage, younger PM children showed a common sound sequence advantage, and AVM children showed no effect. Moreover, error analyses indicated that children with PD had particular difficulty creating lexical representations and associations between lexical and semantic representations when learning common sound sequences. Children with PD may rely more heavily on lexical representations to learn new words or may have difficulty learning common sound sequences because of the high degree of similarity between these sequences and other known words. Finally, the effect of phonotactic probability was consistent across IN and OUT sound sequences, suggesting that the lexical representation of both correctly articulated and misarticulated words is based on the adult-target pronunciation.

Articulation Disorders↗
PubMed1990

Attentional functioning and relational learning.

Stimulus properties such as similarity-dissimilarity and novelty-familiarity are inherently relational and are embedded in ubiquitous stimulus contexts. Children with mental retardation and young children without mental retardation are particularly prone to failure on relational tasks such as oddity and match-to-sample (Greenfield, 1985; Soraci et al., in press). Converging evidence from a number of studies suggest that a critical factor in the performance discrepancies between these and other children is a differential sensitivity to relational information. In these studies relational characteristics of stimulus arrays were enhanced in order to facilitate performances on such relational tasks. Findings indicate the theoretical and practical significance of perceptually based interventions that induce rapid discrimination learning.

Attention↗
PubMed2005

Learning processes in matching and oddity: the oddity preference effect and sample reinforcement.

Eight pigeons learned either matching (to sample) or oddity (from sample) with or without reward for sample responding. The training stimuli were coarse-white, fine-black, or smooth-mauve gravels in pots with buried grain as the reinforcer. Oddity without sample reward was learned most rapidly, followed by matching with sample reward, oddity with sample reward, and matching without sample reward. Transfer was related to acquisition rate: The oddity group without sample reward showed full (equal to baseline) color and texture transfer; the matching group with sample reward showed partial texture transfer; other groups showed no transfer. Sample reward was shown to determine rate of acquisition of matching and oddity and the oddity preference effect. The results are discussed in terms of item-specific associations operating early in learning prior to any relational learning between sample and comparison stimuli.

Analysis of Variance↗
PubMed2005

Biphasic extrathoracic cuirass ventilation for resuscitation.

PURPOSES: The MRTX portable lightweight respirator (MRTX) provides noninvasive respiratory support using biphasic extrathoracic ventilation via a cuirass fitted around the patient's chest. METHODS: MRTX was applied with or without full protective gear, on adult volunteers simulating nerve agent (NA) victims by nonmedical caregivers. Assessment was made based on scores for correct positioning of the cuirass, quality of seal, and rapidness. RESULTS: For the unprotected and protected personnel, the respective median (+/-95% confidence interval) scores for correct positioning of the cuirass were 2 (1.4-1.9) and 1 (1.2-1.8) (n = 15 per group, P = NS); quality of seal scores were 2 (1.5-2.0) and 2 (1.3-1.8) ( P = NS); and mean (+/-SD) time required for instituting mechanical ventilation was 90.5 +/- 10.9 and 100.3 +/- 7.9 seconds ( P < .05). The respirator was activated at first attempt 11 times in the group of 15 without protective gear and 8 times in the group of 15 with protective gear ( P = NS). DISCUSSION: Biphasic cuirass ventilation is an easily learned and rapidly applied method suitable for use by nonmedical personnel, even when wearing cumbersome protective gear.

Adult↗
PubMed1986

Memory storage and retrieval processes in category learning.

The detailed course of learning is studied for categorization tasks defined by independent or contingent probability distributions over the features of category exemplars. College-age subjects viewed sequences of bar charts that simulated symptom patterns and responded to each chart with a recognition and a categorization judgment. Fuzzy, probabilistically defined categories were learned relatively rapidly when individual features were correlated with category assignment, more slowly when only patterns carried category information. Limits of performance were suboptimal, evidently because of capacity limitations on judgmental processes as well as limitations on memory. Categorization proved systematically related to feature and exemplar probabilities, under different circumstances, and to similarity among exemplars of categories. Unique retrieval cues for exemplar patterns facilitated recognition but entered into categorization only at retention intervals within the range of short-term memory. The findings are interpreted within the framework of a general array model that yields both exemplar-similarity and feature-frequency models as special cases and provides quantitative accounts of the course of learning in each of the categorization tasks studied.

Adult↗
PubMed1975

Training and transfer of clustering and cumulative rehearsal strategies in retarded individuals.

Forty-four retarded adolescents varying in MA, IQ, and etiology were taught one of three active rehearsal strategies or assigned to a control condition. Immediate, short-term (1 day), and long-term (2 weeks) transfer of the strategy was assessed by presenting new 9-item serial lists on each day. Exposure durations, which indicated the rate of subject-pacing, showed that the two highest MA-IQ (mean IQ = 55) groups, one diagnosed as organically impaired and the other as cultural-familially retarded, successfully transferred their strategies over three sessions, while no transfer occurred in the lower MA-IQ group (mean IQ = 40). Greater consistency in the expected pattern of exposure durations of high MA-IQ subjects was found in the cumulative-rehearsal group than in the cumulative-clustering group across sessions. During immediate transfer, the best recall was found for the cumulative group, while on short-term transfer both the cumulative and the cumulative-clustering groups learned more rapidly than the clustering or control groups. No significant recall differences during long-term transfer were apparent for high MA-IQ subjects, probably due to a ceiling effect. For retarded individuals with IQs above 50, the cumulative-rehearsal strategy was the most efficient technique for inducing strategy transfer to a categorized serial list.

Adolescent↗
PubMed1995

Uncomplicated central vein catheterization of high risk patients with real time ultrasound guidance.

Internal jugular vein cannulation has become a routine and clinically important aspect of medical care of critically ill patients. The landmark guided technique usually affords rapid and easy vascular access, but is not always successful and may be complicated by arterial puncture, hematoma, or pneumothorax. Some categories of patients, in particular patients with no external landmarks and patients with coagulopathies, appear to be at an increased risk of complications. We report the experience of internal jugular vein cannulation by a single operator with the external landmark technique in 10 patients and with ultrasound guidance in 31 patients, including 12 high risk patients. These patients had severe coagulopathies due to hepatic failure, HELLP syndrome, excess of anticoagulation treatment, or they had no external anatomic landmarks because of anasarca or obesity, were unable to maintain the horizontal position, or were external landmark catheterization failures. With the availability of the ultrasound device, success and complication rates improved markedly, suggesting that the ultrasound technique is easy to learn and rapidly produces an improvement over the external landmark method. In particular the 13 cannulations performed in 12 high risk patients were all successful at the first attempt, with no complications. In the overall population successful cannulations improved from 80% to 100%, first attempt success from 20% to 87% and carotid punctures decreased from 33% to 3.2%. Our results confirm that ultrasound guided cannulation of the internal jugular vein allows safer operation in high risk patients or when access problems are anticipated.

Adult↗