Functional recovery of skilled forelimb use in rats obliged to use the impaired limb after grafting of the frontal cortex lesion with homotopic fetal cortex

The long-term effect of transplanting embryonic frontal cortex into a unilateral frontal cortex lesion has been studied in adult rats. Before surgery, activity in an open field, muscular strength of both forelimbs, and performance in a paw-reaching-for-food task were scored in 26 rats. In 21 animals a unilateral cortex lesion was then made in the forelimb motor area of the hemisphere contralateral to the preferred paw in the paw-reaching-for-food task, while the other 5 animals were sham-operated. On retesting, the lesion animals changed the preferred paw. A solid homotopic transplant of embryonic tissue (embryonic day 17) was then placed in the lesion cavity in 11 of the lesion rats. Three months later neither lesion alone nor lesion plus transplantation affected open field behavior and muscular strength, but the lesion permanently affected performance in the paw-reaching-for-food task, as shown by a change of preferred paw and a functional deficit in the paw contralateral to the lesion. Transplantation ameliorated the deficits caused by the lesion, but this was only evident when animals were forced to reach with the paw contralateral to the lesion plus transplant. The behavioral results were independent of the size of the lesion and graft. Connections between graft and host tissue were studied by means of the fluorescent tracer 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). A dense array of labeled fibers was found in the host cortex adjacent to the transplant. The results suggest that functional recovery depends on grafting but is only evident when the animal is obliged to use the affected limb.     

Transitive choices by a simple, fully connected, backpropagation neural network: implications for the comparative study of transitive inference.

In search of the minimal requirements for transitive reasoning, a simple neural network was trained and tested on the non-verbal version of the conventional "five-term-series task" – a paradigm used with human adults, children and a variety of non-human species. The transitive performance of the network was analogous in several aspects to that reported for children and animals. The three effects usually associated with transitive choices i.e. "symbolic distance", "lexical marking" and "end-anchor", were also clearly shown by the neural network. In a second experiment, where the training conditions were manipulated, the network failed to match the behavioural pattern reported for human adults in the test following an ordered presentation of the premises. However, it mimicked young children's performance when tested with a novel comparison term. Although we do not intend to suggest a new model of transitive inference, we conclude, in line with other authors, that a simple error-correcting rule can generate transitive behaviour similar to the choice pattern of children and animals in the binary form of the five-term-series task without requiring high-order logical or paralogical abilities. The analysis of the training history and of the final internal structure of the network reveals the associative strategy employed. However, our results indicate that the scope of the associative strategy used by the network might be limited. The extent to which the conventional five-term-series task, in absence of appropriate manipulations of training and testing conditions, is suitable to detect cognitive differences across species is also discussed on the basis of our results. Accepted after revision: 29 May 2001 Electronic Publication     

The ADHD Response-Inhibition Deficit as Measured by the Stop Task: Replication with DSM–IV Combined Type, Extension, and Qualification

Although response inhibition has been proposed as a core element of child attention-deficit hyperactivity disorder (ADHD), the literature is heavily reliant on studies using DSM–III–R diagnostic criteria, older methods of measuring response inhibition, samples of boys, and failing to control thoroughly for comorbid problems—both as diagnoses and as subclinical variation. The present study replicated a deficit in response inhibition in the ADHD combined type (DSM–IV, American Psychiatric Association, 1994) using samples matched on age and sex. The study replicated an effect size of approximately d = .6 in boys with ADHD, and observed an even larger effect size for girls, although the Sex × Group interaction was nonsignificant. Children with ADHD also had problems with response output, shown by variable responding. Excluding comorbid conduct disorder, reading disorder, generalized anxiety disorder, obsessive–compulsive disorder, major depression, and posttraumatic stress disorder from the sample did not alter the results. Correlations indicated that response inhibition was associated with both attentional problems and reading level. Covarying for reading problems did not eliminate the ADHD group effect, but the association of response inhibition with reading clearly requires further examination. Overall, the study supported the role of response inhibition in the DSM–IV ADHD combined type, but with key qualifications as to degree of specificity in reference both to comorbid problems and other executive functions.     

Discovering the Alphabetic Principle: A Lost Opportunity for Educational Reform

We review the recently published report by the Committee on the Prevention of Reading Difficulties in Young Children from a behavior analytic perspective. The authors prescribe what children should learn to be successful readers based on the correlates of reading and the developmental progression of reading errors. The report offers no discussion of theoretical models that can be used by teachers and parents to reform reading instruction or specific procedures that have been shown to be effective at promoting various reading skills. We discuss these omissions in terms of the level of research included in the review, the authors' structural approach to synthesizing this research, and the constructivist orientation common to many early childhood educators. The paper concludes by identifying models and strategies from the behavior analysis literature that can be used to guide instruction and offers a modest suggestion for future reviews of reading research.     

自我信息的反应抑制优势：来自神经振荡的证据

为探明个体对自我信息的反应抑制神经机制,记录了被试在完成面孔识别的停止信号任务时的脑电信号。神经振荡结果显示,反应任务中,加工自我面孔引发了更大的同步化δ节律和去同步化β节律;停止任务中,自我面孔引发了更大的去同步化β节律,特别在大脑前额区和中线上。表明,自我信息的反应抑制优势发生在抑制控制阶段,在于增强的β节律的去同步化促进了运动准备,提高了后续的动作抑制的速度。     

言语工作记忆对视觉工作记忆的影响

工作记忆是当前认知心理学中的一个研究热点,而其言语子系统与视觉子系统之间的关系又是一个颇具争论性的问题。实验1、2采用双任务范式考察了言语工作记忆对视觉工作记忆的影响。结果发现,满负荷言语负载条件下的视觉记忆的成绩显著低于无言语负载条件。这表明,言语工作记忆影响了视觉工作记忆任务的完成。     

Making Probabilistic Relational Categories Learnable

Theories of relational concept acquisition (e.g., schema induction) based on structured intersection discovery predict that relational concepts with a probabilistic (i.e., family resemblance) structure ought to be extremely difficult to learn. We report four experiments testing this prediction by investigating conditions hypothesized to facilitate the learning of such categories. Experiment 1 showed that changing the task from a category‐learning task to choosing the “winning” object in each stimulus greatly facilitated participants' ability to learn probabilistic relational categories. Experiments 2 and 3 further investigated the mechanisms underlying this “who's winning” effect. Experiment 4 replicated and generalized the “who's winning” effect with more natural stimuli. Together, our findings suggest that people learn relational concepts by a process of intersection discovery akin to schema induction, and that any task that encourages people to discover a higher order relation that remains invariant over members of a category will facilitate the learning of putatively probabilistic relational concepts.     

Longitudinal study of striatal activation to reward and loss anticipation from mid-adolescence into late adolescence/early adulthood

Adolescent risk-taking behavior has been associated with age-related changes in striatal activation to incentives. Previous cross-sectional studies have shown both increased and decreased striatal activation to incentives for adolescents compared to adults. The monetary incentive delay (MID) task, designed to assess functional brain activation in anticipation of reward, has been used extensively to examine striatal activation in both adult and adolescent populations. The current study used this task with a longitudinal approach across mid-adolescence and late adolescence/early adulthood. Twenty-two participants (13 male) were studied using the MID task at two time-points, once in mid-adolescence (mean age = 16.11; SD = 1.44) and a second time in late adolescence/early adulthood (mean age = 20.14; SD = .67). Results revealed greater striatal activation with increased age in high- compared to low-incentive contexts (incentive magnitude), for gain as well as for loss trials (incentive valence). Results extend cross-sectional findings and show reduced striatal engagement in adolescence compared to adulthood during preparation for action in an incentive context.     

Reducing prejudice via direct and extended cross-group friendship

One of the most exciting developments in intergroup contact theory is the idea that a certain type of contact, cross-group friendship, might be particularly effective at reducing prejudice. In this chapter we review research on two types of cross-group friendship. Direct cross-group friendship refers to friendships that develop between members of different groups. Extended cross-group friendship, on the other hand, refers to vicarious experience of cross-group friendship, the mere knowledge that other ingroup members have cross-group friends. We consider the relationship between both types of cross-group friendship and prejudice and the processes that mediate and moderate these relationships. The research highlights the respective strengths and weaknesses of direct and extended cross-group friendship and illustrates how they might be practically combined in efforts to improve intergroup relations.     

Be aware of the rifle but do not forget the stench: differential effects of fear and disgust on lexical processing and memory

The aim of this study was to investigate the role of discrete emotions in lexical processing and memory, focusing on disgust and fear. We compared neutral words to disgust-related words and fear-related words in three experiments. In Experiments 1 and 2, participants performed a lexical decision task (LDT), and in Experiment 3 an affective categorisation task. These tasks were followed by an unexpected memory task. The results of the LDT experiments showed slower reaction times for both types of negative words with respect to neutral words, plus a higher percentage of errors, this being more consistent for fear-related words (Experiments 1 and 2) than for disgust-related words (Experiment 2). Furthermore, only disgusting words exhibited a higher recall accuracy than neutral words in the memory task. Moreover, the advantage in memory for disgusting words disappeared when participants carried out an affective categorisation task during encoding (Experiment 3), suggesting that the superiority in memory for disgusting words observed in Experiments 1 and 2 could be due to greater elaborative processing. Taken together, these findings point to the relevance of discrete emotions in explaining the effects of the emotional content on lexical processing and memory.