Bidirectional plasticity in striatonigral synapses: a switch to balance direct and indirect basal ganglia pathways

There is no hypothesis to explain how direct and indirect basal ganglia (BG) pathways interact to reach a balance during the learning of motor procedures. Both pathways converge in the substantia nigra pars reticulata (SNr) carrying the result of striatal processing. Unfortunately, the mechanisms that regulate synaptic plasticity in striatonigral (direct pathway) synapses are not known. Here, we used electrophysiological techniques to describe dopamine D(1)-receptor-mediated facilitation in striatonigral synapses in the context of its interaction with glutamatergic inputs, probably coming from the subthalamic nucleus (STN) (indirect pathway) and describe a striatonigral cannabinoid-dependent long-term synaptic depression (LTD). It is shown that striatonigral afferents exhibit D(1)-receptor-mediated facilitation of synaptic transmission when NMDA receptors are inactive, a phenomenon that changes to cannabinoid-dependent LTD when NMDA receptors are active. This interaction makes SNr neurons become coincidence-detector switching ports: When inactive, NMDA receptors lead to a dopamine-dependent enhancement of direct pathway output, theoretically facilitating movement. When active, NMDA receptors result in LTD of the same synapses, thus decreasing movement. We propose that SNr neurons, working as logical gates, tune the motor system to establish a balance between both BG pathways, enabling the system to choose appropriate synergies for movement learning and postural support.     

Recording online processes in task-oriented reading with Read&;Answer

We present an application to study task-oriented reading processes called Read&Answer. The application mimics paper-and-pencil situations in which a reader interacts with one or more documents to perform a specific task, such as answering questions, writing an essay, or similar activities. Read&Answer presents documents and questions with a mask. The reader unmasks documents and questions so that only a piece of information is available at a time. This way the entire interaction between the reader and the documents on the task is recorded and can be analyzed. We describe Read&Answer and present its applications for research and assessment. Finally, we explain two studies that compare readers’ performance on Read&Answer with students’ reading times and comprehension levels on a paper-and-pencil task, and on a computer task recorded with eye-tracking. The use of Read&Answer produced similar comprehension scores, although it changed the pattern of reading times.     

Efficacy of the program "Testas's (mis)adventures" to promote the deep approach to learning

This paper provides information about the efficacy of a tutorial training program intended to enhance elementary fifth graders' study processes and foster their deep approaches to learning. The program "Testas's (mis)adventures" consists of a set of books in which Testas, a typical student, reveals and reflects upon his life experiences during school years. These life stories are nothing but an opportunity to present and train a wide range of learning strategies and self-regulatory processes, designed to insure students' deeper preparation for present and future learning challenges. The program has been developed along a school year, in a one hour weekly tutorial sessions. The training program had a semi-experimental design, included an experimental group (n=50) and a control one (n=50), and used pre- and posttest measures (learning strategies' declarative knowledge, learning approaches and academic achievement). Data suggest that the students enrolled in the training program, comparing with students in the control group, showed a significant improvement in their declarative knowledge of learning strategies and in their deep approach to learning, consequently lowering their use of a surface approach. In spite of this, in what concerns to academic achievement, no statistically significant differences have been found.     

Emergence of self-organized symbol-based communication in artificial creatures

In this paper, we describe a digital scenario where we simulated the emergence of self-organized symbol-based communication among artificial creatures inhabiting a virtual world of unpredictable predatory events. In our experiment, creatures are autonomous agents that learn symbolic relations in an unsupervised manner, with no explicit feedback, and are able to engage in dynamical and autonomous communicative interactions with other creatures, even simultaneously. In order to synthesize a behavioral ecology and infer the minimum organizational constraints for the design of our creatures, we examined the well-studied case of communication in vervet monkeys. Our results show that the creatures, assuming the role of sign users and learners, behave collectively as a complex adaptive system, where self-organized communicative interactions play a major role in the emergence of symbol-based communication. We also strive in this paper for a careful use of the theoretical concepts involved, including the concepts of symbol and emergence, and we make use of a multi-level model for explaining the emergence of symbols in semiotic systems as a basis for the interpretation of inter-level relationships in the semiotic processes we are studying.     

Absence of effect of the change of food context in the activity-based anorexia phenomenon in rats

The goal of this study was to analyse how the context in which animals remain during the period of access to food modulates the development of activity-based anorexia in rats. For this purpose, the effect of changing the context of the activity period and the eating period was measured in terms of body weight loss, reduction in food intake and increase in physical activity. A 2 yen 2 factorial design was implemented, by having or not having access to a running wheel, and by being exposed or not exposed to a context change. Results showed that exposure to different contexts for the wheel and for the food did not affect weight loss, food intake or activity levels. These results are in line with the theoretical position of Epling and Pierce (1992) that activity is induced by the food restriction regime.     

"Just looking at food makes me gain weight": experimental induction of thought-shape fusion in eating-disordered and non-eating-disordered women

Thought-shape fusion (TSF) is a cognitive distortion that can be induced experimentally and is associated with eating pathology. The current study was conducted in order to elucidate the effects of TSF induction in females with eating disorders (n=35), as well as in restrained eaters (n=38) and unrestrained eaters (n=39). It was hypothesized that TSF induction would result in anxiety, guilt, increased feelings of fatness, perceived weight gain and feelings of moral wrong-doing relative to an anxiety and control induction. It was further hypothesized that restrained eaters and individuals with eating disorders would exhibit a stronger reaction to a TSF induction than would unrestrained eaters. The results indicated that, as predicted, TSF can be induced in individuals both with and without eating disorders, and individuals with eating disorders reported the highest levels of "state" TSF after the induction relative to the non-clinical controls. However, contrary to expectations, restrained eaters reported higher levels of perceived weight gain and moral wrong-doing after the anxiety induction (but not the TSF induction) relative to the control induction. Potential mechanisms for this pattern of results are discussed, and the clinical implications of research on TSF are also considered.     

Imagery intervention in open and closed tennis motor skill performance

To assess use of imagery intervention in performance of two tennis motor skills the quasi-experimental design included a pre- and posttest and a control group. The tennis service shot and service receiving skill were selected as representative of open and closed skills, respectively. 48 subjects, male tennis players, whose ages ranged from 16 to 18 yr. (M = 17.2), were divided into two groups: (1) Technical practice only which was used as control group and (2) Imagery group who received both imagery and technical practice. Analysis of covariance showed a significant main effect for the imagery intervention on the closed skill (p = .002). Findings suggest that imaging a positive outcome may be more powerful in improving performance of closed skill movements than of open skill movements.     

Moral judgments, emotions and the utilitarian brain

The investigation of the neural and cognitive mechanisms underlying the moral mind is of paramount importance for understanding complex human behaviors, from altruism to antisocial acts. A new study on patients with prefrontal damage provides key insights on the neurobiology of moral judgment and raises new questions on the mechanisms by which reason and emotion contribute to moral cognition.     

The Reverse-Caricature Effect Revisited: Familiarization With Frontal Facial Caricatures Improves Veridical Face Recognition

Prior research suggests that recognition of a person's face can be facilitated by exaggerating the distinctive features of the face during training. We tested if this 'reverse-caricature effect' would be robust to procedural variations that created more difficult learning environments. Specifically, we examined whether the effect would emerge with frontal rather than three-quarter views, after very brief exposure to caricatures during the learning phase and after modest rotations of faces during the recognition phase. Results indicate that, even under these difficult training conditions, people are more accurate at recognizing unaltered faces if they are first familiarized with caricatures of the faces, rather than with the unaltered faces. These findings support the development of new training methods to improve face recognition.     

The development of intergroup bias in childhood: how social norms can shape children's racial behaviours

The present research examined the developmental course of racial behaviours in childhood. It tested the hypothesis that White children's expressions of racial prejudice do not necessarily decline in middle childhood due to the development of particular cognitive skills but that instead, as argued by the socio-normative approach, children older than seven will go on expressing prejudiced attitudes under appropriate conditions. This would be explained by the presence of an anti-racism norm, along with the existence of values promoting equal rights, which impede blatant expressions of racism. In the first study 283 White children aged 6-7 and 9-10 years performed a task of resource allocation to White and Black target children in conditions of high (White interviewer was present) or low (White interviewer was absent) salience of the anti-racist norm. The 6- to 7-year-old children discriminated against the Black target in both conditions whereas older children discriminated against the Black child only when the anti-racist norm was not salient. In Study 2, 187 White children aged 6-7 and 9-10 years performed the same resource allocation task in conditions of explicit activation of similarity vs dissimilarity or egalitarian vs merit-based norms regarding race relations. Supporting the hypothesis of the role of racist or anti-racist norms on the expression of intergroup discrimination, results have again shown that 6- to 7-year-old children discriminated against the Black target in both conditions while older children presented significantly different prejudiced/nonprejudiced behaviours consistent with the activated norms. These results were discussed in terms of the need for a reanalysis of the assumptions and research results of the cognitive-developmental theory and of further developments in the socio-normative approach regarding the development of prejudice in childhood.