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PubMed1985

Hypothalamic neuropeptides and memory.

Vasopressin and oxytocin exert pronounced effects on behavior by a direct action on the brain. A single injection of vasopressin results in a long-term inhibition of extinction of a conditioned avoidance response suggesting that vasopressin triggers a long-term effect on the maintenance of a learned response, probably by facilitation of memory processes. In addition vasopressin improves passive avoidance behavior, facilitates retention of sexually motivated T-maze choice behavior in male rats, delays extinction of an appetitive discrimination task, affects approach behavior to an imprinting stimulus in ducklings, delays the postcastration decline in copulatory behavior in male rats, prevents or reverses amnesia induced by electroconvulsive shock, CO2 inhalation, pentylenetetrazol or puromycin. The majority of these effects may be explained by stimulatory influences of vasopressin on memory processes. Generally oxytocin exerts effects which are opposite to those of vasopressin and it has been suggested that oxytocin may be an amnesic neuropeptide. Evidence has been obtained that endogenous vasopressin and oxytocin play a physiological role in brain processes related to memory. Various limbic system structures seem to act as the anatomical substrate for the behavioral effects of vasopressin and different neurotransmitter systems seem to be involved. It is postulated that in case vasopressin affects retrieval processes the site of action is located in the amygdala and the dentate gyrus of the hippocampal complex with dopamine and serotonin as the respective neurotransmitter systems involved.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Cardiac concomitants of feedback processing.

This study examined the heart rate changes associated with positive and negative performance feedback in a probabilistic learning task derived from Holroyd and Coles (Psychological Review, 109 (2002) 679). In this task, subjects were presented with six stimuli and asked to respond by pressing a left versus right key. Responses were followed by positive or negative feedback. Subjects had to infer the S-R mapping rule on the basis of feedback provided to them. Two stimuli were consistently mapped onto the left versus right key (100% mapping). Two other stimuli were randomly mapped onto the keys (50% mapping) and responses to the two remaining stimuli received always positive or negative feedback (always condition). Negative feedback was associated with heart rate slowing in the 100% condition. Heart rate slowed following both positive and negative feedback in the 50% condition, but only when the previous encounter with the stimulus was followed by alternate feedback. Heart rate did not differentiate between positive and negative feedback in the always condition. The results were interpreted in support of the hypothesis assuming that heart rate slowing is elicited when performance-based expectations are violated.

Adult↗
PubMed1993

Risk for alcoholism, antisocial behavior, and response perseveration.

Numerous studies have demonstrated the existence of an association between alcoholism and antisocial personality (ASP). The present study tested two hypotheses: First, that nonalcoholic men with a multigenerational familial history (MGH) of alcoholism would play more cards on a card task that has been shown previously to differentiate antisocial populations from normals and, second, that MGH subjects would display more evidence of ASP on two personality questionnaires: The Self-Report Psychopathy scale and the Socialization scale of the California Psychological Inventory. A total of 28 subjects (14 MGH and 14 family history negative for alcoholism [FH-]) were employed in this study. MGH subjects played significantly more cards during the card task than did FH- subjects. However, the two groups did not differ on the ASP questionnaires. The possibility that a subtle frontal-lobe deficit, rather than ASP per se, underlies the poorer performance of the MGH males is discussed.

Adult↗
PubMed2001

Sensitivity of prefrontal cortex to changes in target probability: a functional MRI study.

Electrophysiological studies suggest sensitivity of the prefrontal cortex to changes in the probability of an event. The purpose of this study was to determine if subregions of the prefrontal cortex respond differentially to changes in target probabilities using functional magnetic resonance imaging (fMRI). Ten right-handed adults were scanned using a gradient-echo, echo planar imaging sequence during performance of an oddball paradigm. Subjects were instructed to respond to any letter but "X". The frequency of targets (i.e., any letter but X) varied across trials. The results showed that dorsal prefrontal regions were active during infrequent events and ventral prefrontal regions were active during frequent events. Further, we observed an inverse relation between the dorsal and ventral prefrontal regions such that when activity in dorsal prefrontal regions increased, activity in ventral prefrontal regions decreased, and vice versa. This finding may index competing cognitive processes or capacity limitations. Most importantly, these findings taken as a whole suggest that any simple theory of prefrontal cortex function must take into account the sensitivity of this region to changes in target probability.

Adolescent↗
PubMed2000

Preparatory attention: experiment and theory.

This study investigated attention to a spatial location using a new spatial preparation task. Participants responded to a target dot presented in the center of a display and ignored a distractor dot presented to the right or left of the center. In an attempt to vary the level of preparatory attention directed to the target, the distractor dot was presented prior to the onset time of the target and the relative frequency of distractor dots to target dots within a block of trials was varied. The results from the first three experiments showed that when instructions induce weak preparatory attention to the target location, response times to a target on target-only trials increase substantially as the percentage of trials containing a distractor increases from 0 to 75%. In Experiments 2 and 3, instructions and display saliency were used to induce strong preparatory attention to the target location, resulting in almost constant response times across distractor percentages. Experiment 4 varied percentage of target trials in the absence of distractors, with the result that response times decreased as target trial percentage increased. Accounts of these data by early "activity-based" and late "criterion-based" attention theories are compared, and the early theory is given a more detailed description within the context of a cognitive neuroscience theory of attention.

Adolescent↗
PubMed1998

Categorical inference is not a tree: the myth of inheritance hierarchies.

One enduring principle of rational inference is category inclusion: Categories inherit the properties of their superordinates. In five experiments, I show that people do not consistently apply this principle when evaluating categorical arguments involving natural categories and a single nonexplainable predicate such as all electronic equipment has parts made of germanium, therefore all stereos have parts made of germanium. Participants frequently did not apply the category inclusion rule despite affirming the relevant categorical relation (e.g., stereos are electronic equipment). They failed to apply the rule even when categories were universally quantified unambiguously. Instead, judgments tended to be proportional to the similarity between premise and conclusion categories. Neglect of category inclusion relations was observed using arguments concerning natural kinds, artifacts, and social kinds.

Adult↗
PubMed1996

Reasoning from memory: a lifespan inquiry into the necessity of remembering when reasoning about class inclusion.

In the current experiment, we evaluated the relationship between reasoning and remembering across the lifespan (10-, 13-, 15-, 23-, and 67-year-olds) using color and number class-inclusion tasks. Subjects made judgments when memory load or information load was either high or low. Reading latency, choice latency, and choice accuracy data were collected and analyzed using formal models that partitioned memory and reasoning as well as type of reasoning strategy. The results showed that: (1) study skills, as indexed by reading latency, were sophisticated across the lifespan; (2) the difference between color and number choice latencies increased with age; (3) reasonably consistent effects were obtained as a function of increasing memory load, with the quality of both reasoning and remembering being adversely affected; (4) different effects were obtained at each age as a function of increasing information load; and (5) the major developmental trend across the lifespan was a tradeoff between class-inclusion and subclass-subclass forms of reasoning. A number of extant theoretical approaches were discussed, none of which were able to account for variations in class-inclusion performance across the lifespan. What was clear, however, was that memory-reasoning dependencies must be incorporated into any comprehensive theory of cognitive development across the lifespan.

Adolescent↗
PubMed1989

Mental representation and hypothetico-deductive reasoning: the case of the THOG problem.

This article reports three experiments that deal with the source of the difficulty of Wason's (1977) THOG problem. The solution of this problem demands both the postulation of hypotheses and a combinatorial analysis of their consequences. Experiment 1 showed that the generation of the hypotheses is not in itself sufficient to solve the problem. Experiment 2 showed that a version presenting a plausible context for separating the level of data from that of hypotheses produced a better performance than both the original abstract version and a thematic version lacking the plausible context separating the levels. Experiment 3 gave evidence that this context can produce facilitation even with the geometric material of the classic version. This experiment also showed that a pictorial presentation of data and a verbal presentation of hypotheses affect performance negatively. The results demonstrate the role of problem representation in problem solving, and, in particular, the role of homogeneity in representing data and hypotheses in hypothetico-deductive reasoning.

Adult↗
PubMed1992

Children and chess expertise: the role of calibration.

Three studies of calibration are reported. Calibration refers to the accuracy with which one can predict one's own performance. In the first study child chess players, non-chess playing parents, and statistics students were asked to predict chances of winning chess games against hypothetical opponents. These subjective probabilities were compared to the actual probabilities, based on the Elo rating system. Better players' predictions were better calibrated. Confidence and ratings are negatively correlated, indicating that with lower ratings, players re overconfident. Skilled child players' predictions were better calibrated than any of the adults'. In the second study subjects were asked to estimate chances of winning in conjunctive situations, e.g., winning all the rounds in a tournament. Again, better child players were more accurate in their predictions and more accurate than adults. In the third study, child players were asked to predict their chances of winning in a non-chess domain after hearing a hypothetical win/loss history. Higher-rated players' predictions were again better calibrated, even though the domain was outside their expertise. The motivational and cognitive implications of calibration are discussed.

Achievement↗
PubMed2002

Effects of lesions of the orbitofrontal cortex on sensitivity to delayed and probabilistic reinforcement.

RATIONALE: Lesions of the orbital prefrontal cortex (OPFC) can cause pathologically impulsive behaviour in humans. Inter-temporal choice behaviour (choice between reinforcers differing in size, delay and/or probability) has been proposed as a model of "impulsive choice" in animals. OBJECTIVE: The effect of lesions of the OPFC on rats' inter-temporal choice behaviour was examined in two experiments: (1) rats chose between a smaller immediate reinforcer and a larger delayed reinforcer; (2) rats chose between a smaller certain reinforcer and a larger probabilistic reinforcer. METHODS: Under halothane anaesthesia, rats received injections of the excitotoxin quinolinate into the OPFC (0.1 M, 0.5 microl, two injections in each hemisphere), or sham lesions (injections of vehicle). They were trained to press two levers (A and B) for food-pellet reinforcers in discrete-trials schedules. In free-choice trials, a press on A resulted in immediate delivery of one food pellet; a press on B resulted in delivery of two pellets, either following a delay ( d) (experiment 1), or with a probability ( p) <1 (experiment 2). The values of d and p were manipulated across phases of the experiments. The locations of the lesions were verified histologically at the end of the experiment. RESULTS: In experiment 1, both groups showed declining choice of lever B as a function of d. The lesioned rats showed significantly shorter indifference delays ( D50: the value of d corresponding to 50% choice of lever B) than the sham-lesioned rats. In experiment 2, both groups showed declining choice of lever B as a function of the odds against delivery of the two-pellet reinforcer, theta ( theta =[1/ p]-1). The lesioned rats showed lower indifference odds ( theta50: the value of theta corresponding to 50% choice of lever B) than the sham-lesioned rats. In both experiments, the lesioned rats showed extensive atrophy of the OPFC, with sparing of the dorsolateral prefrontal cortex. CONCLUSIONS: The results show that lesions of the OPFC can promote preference for the smaller and more immediate, and the smaller and more certain of two reinforcers. The results are consistent with two interpretations: the lesion may have altered (i) the rates of delay and odds discounting, and/or (ii) sensitivity to the ratio of the sizes of the two reinforcers.

Animals↗
PubMed2002

Behavioral and electrocortical evidence of an interaction between probability and task metrics in movement preparation.

Recent neurophysiological evidence suggests that cognitive factors shape neural activity in cortical areas such as parietal (area 5), premotor, and primary motor cortex. The implication of these findings is that behavioral signatures of cognitive factors and movement-specific factors should likewise be interdependent. The present study provides evidence of this interdependence in both behavioral (reaction time) and electrophysiological (P300) measures. Subjects performed a two-choice pointing task, in which the angular distance between the two required movement directions (task metrics) and the probability of the two responses was varied. In a control condition, a single reaction was required in response to both stimuli to test for the influence of stimulus metrics. Results from the pointing task showed a clear interaction between the metrics and effects of probability. When the potential targets were widely separated (120 degrees), stimulus probability influences reaction time and P300 amplitude in the classic fashion (longer reaction times and larger P300 amplitudes to less probable responses). When pointing to targets that were narrowly separated (20 degrees), probability had no effect: both rare and frequent targets were "functionally frequent." The same interaction was not observed in the control condition, indicating that metrics were primarily influencing movement preparation rather than stimulus processing. The results are consistent with the theoretical framework of dynamic field theory and demonstrate that metrics are an important factor that must be taken into account when assessing the processes associated with movement preparation.

Adolescent↗
PubMed2005

Mental contents in transfer.

The purpose of this paper is to develop theoretical concepts for mental content-based investigations and explanations in the psychology of human thinking in general and transfer more specifically. The schema-based analysis of transfer postulates that the solving of an earlier problem can influence a person's future behavior only to the degree of schematic similarity between the primary and the secondary problem solution. The reported content-based investigation, using Duncker's (1935) classic tumor task, shows however, that the contents of schemata cause an essential variation in a person's mental representation and judgement of radiation confluence effects. The study identified and assessed in separate experiments the influence of three different thought models (additive, balancing, and distribution-based) and two distinct types of spatial images of rays (compact vs. diverging). Whereas differences in the central tendencies of the judgements could expose some of the priming effects between experimental conditions, the core of the content-based analysis was based on the identification of distinct groups of participants displaying a certain type of judgement. These differences reflected the contrasts between the thought models and the ray image content. They substantiated the claim that a schema-based analysis of transfer and reasoning in general, is alone not sufficient to explain interindividual and intercontextual differences that are based on distinctive mental content in the reasoners' apperception.

Adult↗
PubMed2003

Laparoscopic Roux-en-Y gastric bypass: initial 2-year experience.

BACKGROUND: Roux-en-Y gastric bypass (RYGBP)-essentially a restrictive bariatric procedure-is currently considered the gold standard for the surgical treatment of morbid obesity. Open surgery in obese patients is associated with a high risk of cardiopulmonary complications, wound infection, and late incisional hernia. Laparoscopic surgery has been shown to reduce perioperative morbidity and to improve postoperative recovery for various procedures. Herein we present our results with laparoscopic RYGBP after an initial 2-year experience. METHODS: A prospective database was created in our department beginning without the first laparoscopic bariatric procedure. To provide a complete follow-up of 6 months, the results of all patients operated on between June 1999 and August 2001 were reviewed. Early surgical results, weight loss, correction of comorbidities, and improvement of quality of life were evaluated. RESULTS: A total of 107 patients were included. There were 82 women and 25 men, with a mean age of 39.7 years (range, 19-58). RYGBP was a primary procedure in 80 cases (49 morbidly obese and 31 superobese patients) and a reoperation after failure or complication of another bariatric operation in 27 cases. Mean duration of surgery was 168 min for morbidly obese patients, 196 min for surperobese patients, and 205 min for reoperated patients (p <0.01). Conversion to open surgery was necessary in two cases. A total of 22 patients (20.5%) developed complication. Nine of them (8.4%) required reoperation for leak (five cases, or 4.6%), bowel occlusion (three cases, or 2.8%), or subphrenic abscess (one case, or 0.9%). mortality was 0.9%. Major morbidity decreased over time (first two-thirds, 12.5%, last third, 2.7%). major morbidity decreased over time (first two-thirds, 12.5%; last third, 2.7%). Excess weight loss of -50% was achieved in >80% of the patients, corresponding to a loss of 15 body mass index (BMI) units in morbidly obese patients and 20 BMI units in superobese patients. In the vast majority of patients, comorbidities improved or disappeared over time and quality of life improved. CONCLUSIONS: Laparoscopic Roux-en-Y gastric bypass is feasible, but it is a very complex operation. Indeed, it is associated with a long and steep learning curve, as reflected in the high number of major complications among our first 70 patients. The learning curve probably includes between 100 and 150 patients. With increasing experience, the morbidity rate becomes more acceptable and comparable to that of open RYGBP. The results in terms of weight loss and correction of comorbidities are similar to those obtained after open surgery, at least in the short term. However, only surgeons with extensive experience in advanced laparoscopic as well as bariatric surgery should attempt this procedure.

Adult↗
PubMed1991

Effects of preliminary information in a Go versus No-go task.

A series of studies using a Go versus No-go task examined the question of whether preliminary information available early in the recognition of a stimulus is made available to later processes before stimulus recognition is finished, a question relevant to the controversy between discrete and continuous models. Experiment 1 showed that a Go response is faster following a cue indicating that the response probably would be required than following a cue indicating it probably would not be required. Experiments 2-7 were conducted to find out whether analogous preparation occurred when probability of the Go response was signalled by easily discriminable features of a single stimulus rather than a separate cue. The effect was observed when the easily discriminable features uniquely determined the name of the stimulus letter, but not when they merely indicated that the stimulus name was one of two visually similar letters. These results are consistent with the Asynchronous Discrete Coding model, in which the perceptual system makes available to later processes only preliminary information corresponding to discretely activated stimulus attributes.

Attention↗