Numerical magnitude processing impairments in genetic syndromes: a cross‐syndrome comparison of Turner and 22q11.2 deletion syndromes

Cross‐syndrome comparisons offer an important window onto understanding heterogeneity in mathematical learning disabilities or dyscalculia. The present study therefore investigated symbolic numerical magnitude processing in two genetic syndromes that are both characterized by mathematical learning disabilities: Turner syndrome and 22q11.2 deletion syndrome (22q11DS). We further verified whether the phenotypic outcomes of these syndromes emerged from the same or different cognitive processes and therefore examined whether numerical impairments were related to working memory deficits, often observed in these syndromes. Participants were 24 girls with Turner syndrome, 25 children with 22q11DS and 48 well‐matched typically developing control children. All children completed a symbolic numerical magnitude comparison task and four additional working memory tasks. Both groups of children with genetic syndromes showed similar impairments in symbolic numerical magnitude processing compared to typically developing controls. Importantly, in Turner syndrome, group differences in symbolic numerical magnitude processing disappeared when their difficulties in visual‐spatial working memory were taken into account. In contrast, the difficulties in 22q11DS were not explained by poor visual‐spatial working memory. These data suggest that different factors underlie the symbolic numerical magnitude processing impairments in both patient groups with mathematical learning disabilities and highlight the value of cross‐syndrome comparisons for understanding different pathways to mathematical learning disabilities or dyscalculia.     

Cognitive-affective neuroscience of somatization disorder and functional somatic syndromes: reconceptualizing the triad of depression-anxiety-somatic symptoms

Somatization disorder is a somatoform disorder that overlaps with a number of functional somatic syndromes and has high comorbidity with major depression and anxiety disorders. Proposals have been made for revising the category of somatoform disorders, for simplifying the criteria for somatization disorder, and for emphasizing the unitary nature of the functional somatic syndromes in future classifications. A review of the cognitive-affective neuroscience of somatization disorder and related conditions suggests that overlapping psychobiological mechanisms mediate depression, anxiety, and somatization symptoms. Particular genes and environments may contribute to determining whether symptoms are predominantly depressive, anxious, or somatic, and there are perhaps also overlaps and distinctions in the distal evolutionary mechanisms that produce these symptoms.     

Consciousness and Commentaries

There are several neuropsychological syndromes in which good residual function is retained in the absence of acknowledged awareness, among them blindsight, amnesia, and unilateral neglect. All of them point to the need in studying conscious awareness not only for an “on-line” demonstration of the relevant capacity, but for an independent commentary or classificatory response by the subject, whether human or animal. The parametric limits of blindsight (visual discrimination without awareness) can be measured using a “commentary key” psychophysical paradigm, and the results may possibly allow an approach to identifying neural structures involved in visual awareness.     

Spatial orienting in the visual field: a unified perceptual space?

Visual attention can be oriented toward a spatial location in the visual field exogenously by an abrupt onset of a peripheral cue. In a series of behavioral studies on exogenous orienting of attention with a double-cue paradigm, we demonstrated a functional subdivision of perceptual space in the visual field. Specifically, inhibition of return (IOR) is much stronger at periphery relative to perifoveal visual field up to approximately 15° eccentricity, suggesting two dissociable functional areas in the visual field. To further investigate the generality of this functional subdivision of the visual field, we measured IOR effects with another single-cue paradigm and applied a very short cue-target interval that was typically anticipated not to observe any inhibitory effect at all. Consistent with this expectation, no IOR effects at the eccentricities up to 15° were observed. However, significant IOR effects beyond 15° eccentricities were consistently demonstrated. These results not only revealed an early onset of IOR for more peripheral stimuli, but also confirmed that the perceptual space in the visual field is not homogeneous but underlies a functional subdivision with a border of ca. 15° eccentricity.     

Pure optic ataxia and visual hemiagnosia – extending the dual visual hypothesis

Goodale and Milner's two visual system hypothesis is an influential model for the understanding of the primate visual system. Lesions of either the ventral (occipito‐temporal) or the dorsal (occipito‐parietal) stream produce distinct and dissociated syndromes in humans: visual agnosia is typical for ventral damage, whereas optic ataxia (OA) for dorsal damage. We studied the case of a 59‐year‐old left‐handed woman with a circumscribed lesion around the left posterior occipital sulcus, extending to the underlying white matter. Initially, she presented with a central visual field OA, which regressed to an OA to the right visual hemifield during the 3 months observation period. In addition, tachistoscopic experiments showed visual hemiagnosia to the right visual hemifield. In line with the findings of the neuropsychological experiments, the analysis of the structural MR data by means of a trackwise hodologic probabilistic approach revealed damage to the left superior longitudinal fasciculus and to the left inferior longitudinal fasciculus, indicating an impairment of both the dorsal and the ventral stream. The combination of OA and visual hemiagnosia in the same patient has never been previously described. The present case study thus provides further insights for the understanding of visual processing.     

Seeing why they cannot see: Understanding the syndrome and causes of posterior cortical atrophy

Posterior cortical atrophy (PCA) is a syndrome defined by focal neurodegeneration of the parietal, occipital, and occipito‐temporal cortices and associated with progressive dysfunction of visual processing, praxis, numeracy and reading. The condition is most commonly caused by (and viewed as an atypical presentation of) Alzheimer's disease, although can also be caused by other degenerative diseases. The current paper examines the relationship of PCA to other degenerative syndromes, and considers what comparisons of these syndromes and disease phenotypes can tell us about underlying disease mechanisms. The focus then turns to neuropsychological investigations of the cognitive basis of symptoms which, although unusual in the broader context of a dementia clinic, are particularly characteristic of the PCA syndrome, before exploring implications for clinical management and patient and carer support.     

Spatial orienting in the visual field: a unified perceptual space?

Visual attention can be oriented toward a spatial location in the visual field exogenously by an abrupt onset of a peripheral cue. In a series of behavioral studies on exogenous orienting of attention with a double-cue paradigm, we demonstrated a functional subdivision of perceptual space in the visual field. Specifically, inhibition of return (IOR) is much stronger at periphery relative to perifoveal visual field up to approximately 15° eccentricity, suggesting two dissociable functional areas in the visual field. To further investigate the generality of this functional subdivision of the visual field, we measured IOR effects with another single-cue paradigm and applied a very short cue-target interval that was typically anticipated not to observe any inhibitory effect at all. Consistent with this expectation, no IOR effects at the eccentricities up to 15° were observed. However, significant IOR effects beyond 15° eccentricities were consistently demonstrated. These results not only revealed an early onset of IOR for more peripheral stimuli, but also confirmed that the perceptual space in the visual field is not homogeneous but underlies a functional subdivision with a border of ca. 15° eccentricity.     

Visual identification following inferotemporal ablation in the monkey

Nine monkeys took part in two experiments on visual learning and the effect of inferotemporal ablation. The first experiment contrasted lesion effects in two tasks given to separate groups of animals: serial visual reversal learning set with only two visual stimuli in use throughout the experiment, and discrimination learning set with a new pair of visual stimuli for each discrimination problem. Following inferotemporal ablation, the within-reversal learning rate recovered to the normal pre-operative level, while within-problem learning in discrimination learning set remained substantially impaired. This result suggests that inferotemporal ablation does not directly impair visual associative learning, but rather produces a defect in visual identification such that only a small set of familiar stimuli can be correctly identified and associated with reward. The second experiment replicated an earlier experiment in showing that monkeys with inferotemporal ablation could learn at a normal rate to choose between stimuli according to their spatial orientation. A relation between the two types of unimpaired visual learning in the operated animals was suggested and analogies with clinical syndromes were discussed. The experimental results were interpreted within a distributed-trace model of learning, and this interpretation was illustrated and supported by a computer simulation presented in the Appendix.     

A computational model of semantic memory impairment: modality specificity and emergent category specificity.

It is demonstrated how a modality-specific semantic memory system can account for category-specific impairments after brain damage. In Experiment 1, the hypothesis that visual and functional knowledge play different roles in the representation of living things and nonliving things is tested and confirmed. A parallel distributed processing model of semantic memory in which knowledge is subdivided by modality into visual and functional components is described. In Experiment 2, the model is lesioned, and it is confirmed that damage to visual semantics primarily impairs knowledge of living things, and damage to functional semantics primarily impairs knowledge of nonliving things. In Experiment 3, it is demonstrated that the model accounts naturally for a finding that had appeared problematic for a modality-specific architecture, namely, impaired retrieval of functional knowledge about living things. Finally, in Experiment 4, it is shown how the model can account for a recent observation of impaired knowledge of living things only when knowledge is probed verbally.     

Attentional factors in visual field asymmetries.

Over the past 30 years, numerous studies have reported left/right asymmetries in visual field performance, with performance generally superior in the right visual field for verbal tasks and in the left visual field for spatial tasks. These asymmetries parallel those found in neurological studies of hemispheric specialization. Consequently, many investigators have concluded that visual hemifield differences are primarily a reflection of the functional differences between the two cerebral hemispheres. However, alternative explanations proposing that visual field effects are dependent on other factors such as inadequate fixation, eye movements during presentation, postexposural scanning, and attentional biases have been offered. The potential impact of each of these factors on visual field differences are reviewed and discussed. Evidence is provided suggesting that attention and hemispheric functional differences interact to produce the magnitude and direction of visual field differences.     

The visual word form area: expertise for reading in the fusiform gyrus

Brain imaging studies reliably localize a region of visual cortex that is especially responsive to visual words. This brain specialization is essential to rapid reading ability because it enhances perception of words by becoming specifically tuned to recurring properties of a writing system. The origin of this specialization poses a challenge for evolutionary accounts involving innate mechanisms for functional brain organization. We propose an alternative account, based on studies of other forms of visual expertise (i.e. bird and car experts) that lead to functional reorganization. We argue that the interplay between the unique demands of word reading and the structural constraints of the visual system lead to the emergence of the Visual Word Form Area.     

The Influence of Boundaries on Young Children's Searching and Gathering

Two experiments were conducted to examine how boundaries influence the organization of the gathering and searching of 3- and 4-year-olds. In Experiment 1, children retrieved miniature carrots that were in plain view from a dollhouse that was divided in half by a visual, a functional, or a visual-functional boundary. There was also a control condition in which no boundary was present. Children exhibited more organized gathering in the visual and visual-functional boundary conditions than in the functional boundary and no-boundary conditions. This suggests that visual rather than functional properties of boundaries influenced the organization of young children's gathering behavior. In Experiment 2, we increased task difficulty by requiring children to search for carrots that were out of sight. Unlike in Experiment 1, children produced more organized searching in the visual, visual-functional, and the functional boundary conditions than in the no-boundary condition. Our discussion focuses on the role of the physical environment in organizing behavior.     

Psychotherapeutic Interventions and Processes

Cognitive behavioral therapy (CBT) has been one of the most influential developments in psychiatry ever. Since it was developed and introduced, a vast number of treatment protocols focused on specific psychiatric syndromes have been developed. Although this has benefitted many patients and advanced the field, CBT as a treatment with its focus on alleviating psychiatric syndromes seemed to have reached a plateau and a process-focus approach is now emerging within the family of CBT models. This represents a new form of idiographic functional analysis guided by models that integrate a coherent set of change processes. Here, I describe the foundations of this new approach to mental health, called process-based therapy (PBT) and discuss its scientific and clinical implications.     

视觉表象产生加工的可塑性水平研究

采用标准化的视觉表象产生任务,以经过系统训练以及三个不同年龄阶段被试为研究对象来研究视觉表象产生加工时所表现出的可塑性水平。研究结果表明,视觉表象产生加工水平会因外界系统训练而发生功能增强的练习效应,也表现出随着个体的发展所呈现出的年龄效应,年幼儿童还不能产生空间表征,9岁左右可能是儿童类别表象产生能力发展的一个重要时期,也是个体视觉表象产生加工能力可塑性最高的时期。说明由于受大脑神经细胞活动特性改变的影响,视觉表象产生能力具有相对较高的可塑性和易变性特点。     

发展性阅读障碍的视觉空间注意加工能力

鉴于阅读起始于基础视觉加工阶段, 越来越多的研究者开始关注阅读障碍者的视觉空间注意加工能力。视觉空间注意是指个体对视觉刺激的空间位置的注意, 可通过线索提示、视觉搜索和视觉注意广度等视觉任务来考察。大量国内外研究发现, 发展性阅读障碍者在视觉空间注意任务下表现出行为和神经活动方面的异常。其中的神经机制问题不仅反映在与视觉空间注意有关的顶叶区域激活异常, 还存在于脑区间功能连接异常(如顶叶区域与字形加工区的功能连接)。未来研究还需利用横断和追踪研究探讨阅读障碍与视觉空间注意能力发展关系的内在机制, 以及探究语言特性对阅读障碍者视觉空间注意缺陷的可能调节作用。     

The likely success of functional analysis tied to the DSM

Nelson-Gray and Farmer argue that behavioral assessment and functional analysis may be beneficially applied to personality disorders (PDs). While this is a reasonable response to the largely non-behaviorally derived Diagnostic and Statistical Manual (DSM), it is not yet clear that grafting such theoretically incongruent elements will be viable. In essence, they argue that a syndromal classification system could serve a nomothetic role of guiding a functional, idiographic analysis. This is possible, but it seems unlikely that this process would remain in equilibrium, with no interactive effect of the functional analysis on the syndromes themselves. Yet the DSM system has shown itself to be surprisingly closed to a more functional approach, so the relationship between the DSM and functional analysis is not open in both directions. What is needed is a nomothetic level of analysis that is also functionally derived. The primary benefit of functional over syndromal categories is one of treatment utility, a concept that is itself surprisingly absent from the authors' otherwise comprehensive discussion of behavioral assessment.     

Functional and dynamic properties of visual peripersonal space

In order to code visual peripersonal space, human and non-human primates need an integrated system that controls both visual and tactile inputs within peripersonal space around the face and the hand, based on visual experience of body parts. The existence of such a system in humans has been demonstrated, and there is evidence showing that visual peripersonal space relating to the hand has important dynamic properties, for example, it can be expanded and contracted depending on tool use. There is also evidence for a high degree of functional similarity between the characteristics of the visual peripersonal space in humans and in monkeys.     

A quantitative analysis of accuracy,reliability and bias in judgements of functional analyses

Functional analysis can be considered a diagnostic assessment that behavior analysts use to determine behavioral function. Such a diagnosis ultimately requires a yes or no decision (i.e., a variable maintains a behavior, or it does not) that is determined by both subjective (clinical judgement) and objective (data) variables. Accurate and reliable identification of function is essential for successful treatment, yet behavior analysts' interpretation of data relies on their ability to detect visual differences in graphed data. Some research indicates that behavior analysts have questionable reliability in their visual analysis. To further examine the reliability, accuracy, and bias in visual analysis of functional analysis graphs, we simulated functional analysis results and surveyed 121 BCBA-Ds experienced in visual analysis. We then examined reliability of responses and used a signal detection theory approach to analyze accuracy and bias. Findings suggest that reliability and accuracy of judgements are questionable, and exploration of decision aids is warranted.     

Functional disconnection in pure alexia and color naming deficit demonstrated by facilitation methods.

The authors suggest that the possible combinations of pure alexia with concomitant neuropsychological symptoms form a continuum determined by the extent and severity of the brain lesion. The disconnection mechanism underlying these syndromes is demonstrated by the facilitating effect of unblocking methods (in the tactile, somesthetic, auditory, and visual modality) on the reading performance of a pertinent case. In the unblocking situation, other pathways than the one impaired by the brain lesion are used. It is proposed that the color naming deficit is associated with defective verbal identification of graphemic stimuli because of their common linguistic features. The delineation from aphasic color naming and reading deficit is discussed.