Chronic nicotine exposure induces a long-lasting and pathway-specific facilitation of LTP in the amygdala

Nicotine, in the form of tobacco, is the most commonly used drug of abuse. In addition to its rewarding properties, nicotine also affects many cognitive and emotional processes that involve several brain regions, including hippocampus and amygdala. Long-term changes in synaptic strength in these brain regions after drug exposure may be importantly correlated with behavioral changes induced by nicotine. Here, we study the effect of chronic oral administration of nicotine on the long-term synaptic potentiation in the amygdala, a key structure for emotional memory. We find that oral administration of nicotine for 7 d produces a significant enhancement of LTP in the amygdala. This facilitation is pathway specific: Nicotine selectively facilitates LTP in the cortical-lateral amygdala pathway, but not the thalamic-lateral and the lateral-basolateral synaptic pathway. The synaptic facilitation induced by a 7-d exposure to nicotine is long-lasting, it persists for 72 h after cessation of nicotine but decays 8 d after its cessation. In contrast, a shorter exposure of nicotine (24 h) induces only a short-lasting facilitation of synaptic plasticity that dissipates 24 and 72 h after cessation of nicotine. The facilitation of LTP in the amygdala after exposure to nicotine is mediated by removal of GABAergic inhibition, is dependent on the activation NMDA receptors, and can be prevented by blocking either α7 or β2 nACh receptors. Our results indicate that chronic exposure to nicotine can promote the induction of long-lasting modifications of synapses in a specific pathway in the amygdala.These changes in synaptic plasticity may contribute to the complex neural adaptations and behaviors caused by nicotine.     

Factor structure and correlates of the dissociative experiences scale in a large offender sample

The authors examined the psychometric properties, factor structure, and construct validity of the Dissociative Experiences Scale (DES) in a large offender sample (N = 1,515). Although the DES is widely used with community and clinical samples, minimal work has examined offender samples. Participants were administered self-report and interview measures, and a subsample was followed longitudinally to determine criminal and violent recidivism. The DES exhibited good psychometric properties, but an identified three-factor structure was of questionable replicability. Moreover, the DES factors displayed no evidence of differential correlates. DES total scores were correlated with trauma-related variables even after controlling for negative affectivity. Total scores were related to measures of antisocial behavior and aggression but did not predict recidivism. These findings support the reliability and construct validity of the DES in offenders but raise questions regarding the clinical utility of the DES factor scores above and beyond that of the total score.     

Aging preserves the ability to perceive 3D object shape from static but not deforming boundary contours

A single experiment investigated how younger (aged 18-32 years) and older (aged 62-82 years) observers perceive 3D object shape from deforming and static boundary contours. On any given trial, observers were shown two smoothly-curved objects, similar to water-smoothed granite rocks, and were required to judge whether they possessed the "same" or "different" shape. The objects presented during the "different" trials produced differently-shaped boundary contours. The objects presented during the "same" trials also produced different boundary contours, because one of the objects was always rotated in depth relative to the other by 5, 25, or 45 degrees. Each observer participated in 12 experimental conditions formed by the combination of 2 motion types (deforming vs. static boundary contours), 2 surface types (objects depicted as silhouettes or with texture and Lambertian shading), and 3 angular offsets (5, 25, and 45 degrees). When there was no motion (static silhouettes or stationary objects presented with shading and texture), the older observers performed as well as the younger observers. In the moving object conditions with shading and texture, the older observers' performance was facilitated by the motion, but the amount of this facilitation was reduced relative to that exhibited by the younger observers. In contrast, the older observers obtained no benefit in performance at all from the deforming (i.e., moving) silhouettes. The reduced ability of older observers to perceive 3D shape from motion is probably due to a low-level deterioration in the ability to detect and discriminate motion itself.     

Successful Child Psychotherapy of Attention Deficit/Hyperactive Disorder: An Agitated Depression Explanation

Science tries to explain phenomena in ways that are demonstrable and replicable to develop logical, coherent, parsimonious, and predictive theoretical systems. Yet hyperactive children are given stimulants to "calm" them down, despite the fact that science would predict stimulants would increase hyperactivity. Bradley (1937, 1950) observed that half of the behavior-problem children to whom he administered a stimulant for one week became subdued. He called this finding paradoxical, speculating that inhibitory centers of the central nervous system were stimulated. While Bradley's assertion of a paradoxical reverse effect in children may be an empirical observation, it is not an explanation. The Attention Deficit/Hyperactive Disorder (ADHD) is inferred to exist from hyperactive behavior, which in turn, is inferred to be neurological in origin, a circular argument. An inevitable consequence of the belief in the hypothetical neurological etiology of ADHD is that children are typically given stimulants. Using the case of a seven-year old child, described as experiencing ADHD, who was treated successfully without medication as an illustration, the author provides an alternative, more parsimonious explanation of the etiology, suggesting that ADHD is related to agitated depression.     

A Note on Prototypes,Convexity and Fuzzy Sets

The work on prototypes in ontologies pioneered by Rosch [10] and elaborated by Lakoff [8] and Freund [3] is related to vagueness in the sense that the more remote an instance is from a prototype the fewer people agree that it is an example of that prototype. An intuitive example is the prototypical “mother”, and it is observed that more specific instances like ”single mother”, “adoptive mother”, “surrogate mother”, etc., are less and less likely to be classified as “mothers” by experimental subjects. From a different direction Gärdenfors [4] provided a persuasive account of natural predicates to resolve paradoxes of induction like Goodman’s “Grue” predicate [5]. Gärdenfors proposed that “quality dimensions” arising from human cognition and perception impose topologies on concepts such that the ones that appear “natural” to us are convex in these topologies. We show that these two cognitive principles — prototypes and predicate convexity — are equivalent to unimodal (convex) fuzzy characteristic functions for sets. Then we examine the case when the fuzzy set characteristic function is not convex, in particular when it is multi-modal. We argue that this is an indication that the fuzzy concept should really be regarded as a super concept in which the decomposed components are subconcepts in an ontological taxonomy.     

Poor shape perception is the reason reaches-to-grasp are visually guided online

Both judgment studies and studies of feedforward reaching have shown that the visual perception of object distance, size, and shape are inaccurate. However, feedback has been shown to calibrate feedfoward reaches-to-grasp to make them accurate with respect to object distance and size. We now investigate whether shape perception (in particular, the aspect ratio of object depth to width) can be calibrated in the context of reaches-to-grasp. We used cylindrical objects with elliptical cross-sections of varying eccentricity. Our participants reached to grasp the width or the depth of these objects with the index finger and thumb. The maximum grasp aperture and the terminal grasp aperture were used to evaluate perception. Both occur before the hand has contacted an object. In Experiments 1 and 2, we investigated whether perceived shape is recalibrated by distorted haptic feedback. Although somewhat equivocal, the results suggest that it is not. In Experiment 3, we tested the accuracy of feedforward grasping with respect to shape with haptic feedback to allow calibration. Grasping was inaccurate in ways comparable to findings in shape perception judgment studies. In Experiment 4, we hypothesized that online guidance is needed for accurate grasping. Participants reached to grasp either with or without vision of the hand. The result was that the former was accurate, whereas the latter was not. We conclude that shape perception is not calibrated by feedback from reaches-to-grasp and that online visual guidance is required for accurate grasping because shape perception is poor.     

Evaluation of a Peer-Led Mutual Support Group for Chinese Families of People with Schizophrenia

Family interventions in schizophrenia have shown positive effects on patients but little attention has been paid to their effects on family members, particularly those in non-Western countries. This randomized controlled trial evaluated the effectiveness of a bi-weekly, 12-session, family-led mutual support group for Chinese caregivers of schizophrenia sufferers over 6 months compared with standard psychiatric care. It was conducted with 76 families of outpatients with schizophrenia in Hong Kong of whom 38 were assigned randomly to either a mutual support group or standard care. Families' psychosocial health status and patients' symptom severity and length of re-hospitalizations at recruitment, one-week and 12-month post-intervention were compared between groups. Results of repeated-measures mixed model indicated that the mutual support group experienced significantly greater improvements in families' burden, functioning and number of support persons and length of patients' re-hospitalizations at two post-tests. The findings provide evidence that mutual support groups can be an effective family-initiated, community-based intervention for Chinese schizophrenia sufferers.