Behavioral and electrophysiological evidence of different processes during a target identification task assessing perceptual learning.

This study aimed to test whether a target identification task involving same and different judgments to assess the ability to differentiate between similar pre-exposed stimuli-i.e., perceptual learning-could actually be assessing two different cognitive processes. Specifically, the hypothesis was that while "different" trials might be truly assessing the ability to differentiate between the pre-exposed stimuli, "same" trials might be assessing the ability to recognize one of these stimuli as the target. To test this hypothesis, accuracy on judgments as well as reaction times and event-related potentials for same/different trials were recorded after concurrent pre-exposure to similar stimuli. If same/different trials were assessing cognitive processes with different time courses, distinct outcomes for such trials would be expected at the behavioral and neural level. Results showed that participants were very accurate both in same and different judgments, indicating that they were perfectly able to differentiate between the stimuli after their concurrent presentations. However, larger P3 latencies and slower reaction times for different trials than for same trials were found. These results seem to support the idea that cognitive processes activated in same and different trials are different due to their distinct time courses. The importance of these findings for the theoretical approaches to perceptual learning is discussed.

Extinction in multiple contexts reduces the return of extinguished responses: A multilevel meta-analysis.

Extinguished responses have been shown to reappear under several circumstances, and this reappearance is considered to model behaviors such as relapse after exposure therapy. Conducting extinction in multiple contexts has been explored as a technique to decrease the recovery of extinguished responses. The present meta-analysis aimed to examine whether extinction in multiple contexts can consistently reduce the recovery of extinguished responses. After searching in several databases, experiments were included in the analysis if they presented extinction in multiple contexts, an experimental design, and an adequate statistical report. Cohen's d was obtained for each critical comparison and weighted to obtain the sample's average weighted effect size. Analyses were then performed using a multilevel meta-analytic approach. Twenty-five studies were included, with a total sample of 37 experiments or critical comparisons. The analyses showed a large effect size for the sample, moderated by the length of conditioned stimulus exposure, type of experimental subject, and type of recovery. The robust effect of extinction in multiple contexts on relapse should encourage clinicians to consider extinction in multiple contexts as a useful technique in therapy and research.

Sexual dimorphism in classical conditioning? Sex differences in neophobia, latent inhibition, generalization, and extinction for rats (Rattus norvegicus) in a conditioned taste aversion preparation irrespective of housing conditions.

This study aimed to assess possible sex differences and a potential impact of social housing conditions for some Pavlovian conditioning effects in a conditioned taste aversion preparation with rats. The results of Experiment 1 suggest sex differences in neophobia, latent inhibition, and generalization. Specifically, for females, neophobia, and generalization appeared to be stronger while latent inhibition seemed to be attenuated. Experiment 2 confirmed these sex differences in neophobia and generalization, while also revealing slower extinction in males. Experiment 3 provided evidence for the same sex differences in neophobia and generalization, even when a perceptual learning effect was in operation following pre-exposures to the test stimulus. No effects of social housing conditions were found in either Experiment 1 or Experiment 2. In general, these findings appear to support the hypothesis of sexual dimorphism in Pavlovian conditioning, encouraging a systematic approach to the topic by means of further research. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Response reduction and stimulus pre-exposure effects in a human conditioning method.

Two experiments with humans determined whether reduced conditioning following pre-exposure to the conditioned stimulus could be explained by conditioned inhibition (Experiment 1 [E1]) or extinction of responding that the conditioned stimulus (CS) might elicit during pre-exposure (Experiment 2 [E2]). In a video game task (Nelson et al., 2014), participants learned to respond to lights that signaled attacking spaceships. In E1, a red light was either pre-exposed or not pre-exposed between groups prior to conditioning with a green light. Summation tests of red combined with green produced no evidence of conditioned inhibition. In E2, participants received either no pre-exposure to the light, exposure in the same context in which the conditioning would occur, or exposure in a different context. These conditions were factorially combined with whether the light and spaceship were similar (same color) or dissimilar (different colors). In the similar conditions, the light elicited weak responding during pre-exposure, which extinguished. Such extinction did not occur in the dissimilar conditions. Conditioning occurred more rapidly in the similar conditions than in the dissimilar ones, but both conditions showed an equivalent context-dependent pre-exposure effect. Pre-exposure reduced conditioning regardless of whether it reduced responding prior to conditioning. The data are consistent with animal research (Lubow et al., 1968) showing no relation between responding during pre-exposure and the effects of stimulus pre-exposure. Theories which account for the effects of stimulus pre-exposure are discussed, with the conclusion that the data are most consistent with the ideas presented by Wagner (1981). (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Sex Differences in Cue Competition Effects With a Conditioned Taste Aversion Preparation.

This study aimed to test whether male and female rats might show differences in cue competition effects in a conditioned taste aversion (CTA) model. Experiment 1 tested for sex differences in overshadowing. After conditioning of a flavored compound AB or only one simple flavor A (being A and B a solution of sugar 10% and salt 1%, counterbalanced), consumption of the A solution at test was larger in the former than in the latter case only in males. Thus, the usual effect of overshadowing was observed in males but not in females. Experiment 2 examined sex differences in blocking with the same stimuli used in Experiment 1. After conditioning of AB, the consumption of B was larger for the animals that previously received a single conditioning trial with A than for those that received unpaired presentations of A and the illness. As observed in Experiment 1, the typical blocking effect appeared only in males but not in females. The present findings thus support the hypothesis that sex dimorphism might be expressed in classical conditioning, or at least, in cue competition effects such as overshadowing and blocking with a taste aversion model.

Age, sex and pre-exposure effects on acquisition and generalization of conditioned taste aversion in rats.

The main aim of the present study was to assess the effect of sex and aging in two pre-exposure learning effects, latent inhibition (LI) and perceptual learning (PL), with a conditioned taste aversion paradigm. Young adult (90 days) and aged (more than 18 months) males and females received 8 pre-exposure trials either with stimulus AX (LI conditions) or BX (PL conditions). Then, all animals received a conditioning trial with AX and two test trials, one with AX and other with BX. The level of generalization between AX and BX was assessed by means of the absolute level of consumption of BX and by the difference in consumption between both stimuli. The results showed an attenuation of latent inhibition as well a stronger generalization of conditioned taste aversion in females when generalization is inferred from the BX consumption. A facilitation of conditioning for the aged animals was also found regardless of the pre-exposed stimulus. Pre-exposures to BX resulted in little generalization, but pre-exposures to AX resulted in a very similar consumption of both compounds, indicating a strong generalization between them. Overall, the study provided novel evidence about the effect of sex and aging on taste aversion, raising at the same time some relevant questions about perceptual learning and how such pre-exposure effect has been typically assessed.

Pre-exposure Schedule Effects on Generalization of Taste Aversion and Palatability for Thirsty and Not Thirsty Rats.

The study reported four experiments aiming to test the effects of the pre-exposure schedule and water deprivation on the generalization of a conditioned taste aversion in rats, with a particular focus on testing whether or not the concurrent schedule might enhance generalization. In two experiments, non-water-deprived rats received concurrent, intermixed, or blocked exposure to a sweet-acid solution and a salty-acid solution before conditioning of one of these compounds and testing of both flavors. During pre-exposure, the rats consumed a greater amount of the sweet-acid solution than the salty-acid solution (Experiments 1 and 2), consumption of the former increasing during pre-exposure while consumption of the latter decreased (Experiment 1). Furthermore, consumption of the salty-acid solution was lower during concurrent than intermixed or blocked pre-exposure (Experiment 1 and 2) while consumption of the sweet-acid solution was greater during intermixed than concurrent or blocked pre-exposure (Experiment 1). It is discussed whether the pre-exposure schedule might modify stimulus perception beyond the mere enhancement of stimulus differentiation, by, for instance, affecting the palatability of gustatory stimuli. Evidence for enhanced generalization after concurrent pre-exposure was not found for either deprived (Experiments 1, 2, and 3) or non-deprived rats (Experiments 3 and 4), with deprivation leading to a general increase in consumption of both the conditioned and test flavors. This then raised the question of whether or not concurrent pre-exposure to flavors always increases generalization between them. The present study highlights the importance of this issue for various accounts of perceptual learning.

Stimulus similarity decreases spontaneous object recognition regardless of the retention interval in rats / La similitud entre estímulos reduce el reconocimiento espontáneo de objetos en ratas independientemente del intervalo de retención

The experiment aimed to test in a spontaneous object recognition (SOR) task the effects of stimulus similarity and the interval between a previous familiarization trial and such a task. 1h or 24 h after the familiarization trial with two identical copies of an object, exploration of one of the objects and another novel object was assessed by recording the number of approaches, as well the time spent close to them. On the test the stimuli could either differ slightly in form (Difficult discrimination condition) or markedly in form and color (Easy condition). Subjects in the Easy but not the Difficult condition preferred to explore the novel object regardless of the retention interval (1h or 24h). After the 24h interval, exploration of the novel stimulus was greater for subjects in the Easy than the Difficult condition but they did not differ in terms of exploring the familiar object. Thus, rats in the Difficult condition might remember the familiar stimuli as well as rats in the Easy condition after 24 h, but were unable to distinguish it from the novel stimulus. The implications of this notion for using the SOR task as a procedure for studying perceptual learning and memory are discussed (AU)

El objetivo del experimento fue comprobar en una tarea de reconocimiento espontáneo de objetos el efecto de la similitud de los estímulos y el intervalo de retención entre esta tarea y un ensayo previo de familiarización. 1 hora o 24 horas después de la familiarización con dos copias idénticas del mismo objeto, se midió la exploración de uno de estos objetos y otro nuevo registrando la duración y número de aproximaciones a cada objeto. En la tarea los estímulos difirieron ligeramente en su forma (condición de Discriminación Difícil) o marcadamente en forma y color (Condición de discriminación Fácil). Independientemente del intervalo de retención, la condición Fácil pero no la condición Difícil, prefirió explorar el objeto nuevo. Después del intervalo de 24 horas, la condición Fácil exploró el objeto nuevo más que la condición Difícil pero no difirieron en la exploración del estímulo familiar. Entonces, las ratas de la condición Difícil podrían haber recordado el estímulo familiar tan bien como las ratas de la condición Fácil pero fueron incapaces de distinguirlo del estímulo nuevo. Se discuten las implicaciones de esta posibilidad en la utilización de tareas de reconocimiento espontáneo de objetos para el estudio del aprendizaje perceptivo y la memoria (AU)

Percutaneous complete repair of failed mitral valve prosthesis: simultaneous closure of mitral paravalvular leaks and transcatheter mitral valve implantation - single-centre experience.

AIMS: Structural deterioration and paravalvular leak (PVL) are complications associated with surgically implanted prosthetic valves, historically requiring reoperation. We present our experience of complete transcatheter repair of a degenerated mitral bioprosthesis. METHODS AND RESULTS: From March 2012 to October 2012, we reviewed consecutive, high-risk surgical patients (n=5) who underwent transcatheter repair of a failed mitral bioprosthesis with severe paravalvular regurgitation (PVR). Manufacturer valve sizes ranged from 27 to 33 mm, regurgitation (n=1), stenosis (n=1), or both (n=3). Percutaneous transapical and transseptal access were achieved with PVL closure performed transapically. An arteriovenous rail was created for transseptal delivery of a Melody valve. All patients had successful PVL closure with no residual PVR. Valve-in-valve (ViV) implantation was successful in four patients. Overall, mean transvalvular mitral gradient was 11.2 mmHg pre-procedure which improved to 5 mmHg post-procedure. Improvement of NYHA Class ≥2 was achieved in all patients (19±3 months). One patient had controlled Melody valve embolisation which required emergent surgical replacement. Inner valve diameter was 26 mm, too large for Melody valve implantation. CONCLUSIONS: Complete transcatheter repair of a degenerated mitral bioprosthesis with PVR can be performed in the high-risk patient. Accurate measurement is necessary prior to intervention, with concern for embolisation among the larger valve sizes (>31 mm).

¿Se está controlando las complicaciones del TAVI? / Complications of TAVI. Are they under control?

El procedimiento de implante valvular aórtico transcatéter se asocia a tasas relativamente altas de complicaciones, que en algunos casos pueden ser graves. Desde las experiencias iniciales, la mejora en el diseño de dispositivos y en la técnica de implante, unida a un mayor conocimiento de las complicaciones y sus factores de riesgo, ha contribuido en muchos casos a reducir significativamente su incidencia. En este artículo se revisa la evidencia actual sobre las complicaciones más importantes del implante valvular aórtico transcatéter (AU)

Transcatheter aortic valve implantation is associated with a relatively high rate of complications, which can be serious in some cases. However, the improvements in device design and implantation techniques that have taken place since early experience with the procedure, combined with better understanding of possible complications and their risk factors, have contributed to a substantial reduction in the incidence of most complications. This article reviews recent findings on the most important complications of transcatheter aortic valve implantation (AU)

Simultaneous stimulus preexposure enhances human tactile perceptual learning / La preexposición simultánea a los estímulos favorece el aprendizaje perceptivo táctil en humanos

An experiment with human participants established a novel procedure to assess perceptual learning with tactile stimuli. Participants received unsupervised exposure to two sandpaper surfaces differing in roughness (A and B). The ability of the participants to discriminate between the stimuli was subsequently assessed on a same/different test. It was found that prior exposure to the stimuli led to more accurate judgements on the differenttrials. Furthermore, simultaneous exposure to the stimuli enhanced this accuracy more than sequential exposure (A, B, A, B…). These findings extend recent results from visual studies to the tactile modality, confirming that simultaneous exposure produces a marked perceptual learning effect (AU)

Se validó un nuevo procedimiento para medir aprendizaje perceptivo con estímulos táctiles y participantes humanos. Los participantes recibieron exposición no supervisada a dos superficies de lija con diferente rugosidad (A y B). Posteriormente, a través de una prueba de juicios de igual-diferente se valoró la habilidad de los participantes para discriminar entre los estímulos. Se encontró que la exposición previa a los estímulos produjo un aumento en la exactitud de los juicios "diferentes". Además, este aumento fue mayor cuando los estímulos fueron expuestos de forma simutánea que cuando fueron expuestos de forma secuencial. Estos resultados extienden a la modalidad táctil otros resultados recientes con estímulos visuales y confirman que la exposoción simultánea aumenta los efectos de aprendizaje perceptivo (AU)

Attentional changes in human perceptual learning.

In two experiments, participants were required to identify a target stimulus by means of same/different judgments. Previously, they had received simultaneous or blocked pre-exposures to the target and a similar stimulus. Participants' ability to judge pre-exposed stimuli as different was better after simultaneous than after blocked pre-exposures. However, the benefit of the simultaneous schedule disappeared when, after pre-exposure, the distinctive elements were made common (and some common elements made distinctive) by changing their shape and position within the stimulus (Experiment 1). Similar results were obtained when only one of the aforementioned physical features was modified (Experiment 2). These manipulations did not affect performance when the stimuli had been pre-exposed in separate blocks of trials. These findings support the idea that the effect of simultaneous pre-exposure on stimulus differentiation is based on a selective attention process by which attention is selectively directed towards the distinctive features of the stimuli and away from the common features (Gibson, 1969).

Human perceptual learning: the effect of pre-exposure schedule depends on task demands.

The effects of the pre-exposure schedule (concurrent, intermixed, and blocked) to two similar visual stimuli were assessed in three different tasks. Participants were more accurate identifying one of two pre-exposed stimuli as the target by means of same/different judgments after concurrent than intermixed or blocked pre-exposures. Regardless of pre-exposure schedule, participants were accurate in identifying the same target stimulus in a subsequent multiple choice task. However, the other pre-exposed stimulus was incorrectly chosen as the target in a greater proportion after blocked than intermixed or concurrent pre-exposure. Finally, participants who received the blocked schedule showed a greater ability to construct the target in a puzzle test than those who received a concurrent or intermixed schedule. These results suggest that the effect of pre-exposure schedule may depend on task-specific demands. But all these results might be explained by a selective attention mechanism like that proposed by Gibson (1969) to account for perceptual learning.