The development of reading impairment: a cognitive neuroscience model

This review discusses recent cognitive neuroscience investigations into the biological bases of developmental dyslexia, a common disorder impacting approximately 5 to 17 percent of the population. Our aim is to summarize central findings from several lines of evidence that converge on pivotal aspects of the brain bases of developmental dyslexia. We highlight ways in which the approaches and methodologies of developmental cognitive neuroscience that are addressed in this special issue-including neuroimaging, human genetics, refinement of cognitive and biological phenotypes, neural plasticity and computational model-can be employed in uncovering the biological bases of this disorder. Taking a developmental perspective on the biological bases of dyslexia, we propose a simple cascading model for the developmental progression of this disorder, in which individual differences in brain areas associated with phonological processing might influence the specialization of visual areas involved in the rapid processing of written words. We also discuss recent efforts to understand the impact of successful reading interventions in terms of changes within cortical circuits associated with reading ability.     

Early life influences on life-long patterns of behavior and health

The stability of a child's early life has profound effects on physical and mental health, and unstable parent-child relationships, as well as abuse, can lead to behavioral disorders and increased mortality and morbidity from a wide variety of common diseases later in life. One common consequence, namely, depressive illness, is associated with chemical imbalances in the brain and hormonal dysregulation, constituting a form of allostatic load that alters interpretations of stimuli and influences, behavioral, and hormonal responses to potentially stressful situations. The brain not only encodes information and controls the behavioral responses but it is also changed structurally by those experiences. Structural changes in the hippocampus and amygdala, which are important brain structures for cognition and emotion, are representative of what may be occurring throughout the brain as a result of allostatic load resulting from the chronic stress of a disorder such as depression. Such structural changes include dendritic debranching and hypertrophy, cell proliferation, and synaptic remodeling; they are produced by the combined overactivity of stress hormones and endogenous neurotransmitters. These mediators are normally involved in adaptation, but can also promote damage when they are dysregulated and over-active. They are very likely to be strongly biased by early life experiences. The findings from animal models thus provide a basis for understanding potential mechanisms of environmental and developmental determinants of individual differences in human stress reactivity, as well as anxiety, depression, and a host of related systemic disorders. There is an increasing amount of translational research that is beginning to tie the basic research to clinical outcomes of individuals exposed to abusive or inconsistent care-giving in early life. A major goal of studies on this important topic is to define times in development and strategies for intervening to prevent or reverse the effects of adverse early life experiences. Although prevention is clearly the preferable route, some degree of reversal of psychopathology and pathophysiology caused by early life adversity appears to be an achievable goal.     

Looking and search measures of object knowledge in preschool children

The same preschoolers were tested on an observation task and a search task involving the invisible displacement of an object. In the observation task, children watched an object roll behind a screen from which protruded the top of a solid wall. Analyses revealed significantly longer looking to impossible than to possible outcomes in all children. In search, the child was allowed to retrieve the rolled object. Most 3-year-olds but significantly fewer 2.5-year-olds completed the search successfully. An unexpected sex difference was found, with boys outperforming girls. Search performance was not associated with observation measures. The findings indicate that children visually discriminate violations of solidity but that this sensitivity is not associated with successful search performance.     

Long-term semantic transfer: An overlapping-operations account

Semantic priming is usually a short-lived effect. However, it is also usually investigated using undemanding tasks, such as naming or lexical decision. We instead required subjects to perform category verification. We observed semantically mediated transfer occurring at an average lag of 90 intervening trials. We also observed that this priming was specific to the stimulus properties made salient in prime and probe displays and the particular task demanded in those displays. We interpret the results within an overlapping-operations framework, based on the work of Kolers (e.g., 1976).     

Gross-motor skill acquisition by preschool dance students under self-instruction procedures

The effects of two training procedures--(a) modeling and praise and (b) self-instruction, modeling, and praise--on complex gross-motor chain acquisition for preschool dance class students were evaluated. Six girls participated in the study. A multiple baseline design across six gross-motor chains with a secondary group comparison for treatment order effects was used. Both procedures were effective in teaching the gross-motor chains. Nevertheless, for 4 of the 6 participants, the self-instruction procedure produced a faster acquisition rate in at least two of the three comparable pairs of gross-motor chains. Furthermore, very early in gross-motor chain acquisition, for five of the six gross-motor chains, the self-instruction condition was associated with faster response acquisition.     

Chronic pain, stress, and the dynamics of affective differentiation

We describe a program of research examining how the relationship between positive and negative affect varies both between individuals and within individuals over time. This Dynamic Model of Affect (DMA) proposes that under conditions that promote maximal information processing, positive and negative affective systems function relatively independently. In contrast, under conditions characterized by uncertainty, including pain and stress, the affects become strongly inversely related. Included in our consideration are potential individual differences in the ability to sustain affective differentiation during pain and other stressors and the implications of this model for perceptions of social relations and for interventions to improve well-being among the chronically ill.     

Endogenous temporal orienting of attention in detection and discrimination tasks

Endogenous temporal-orienting effects were studied using a cuing paradigm in which the cue indicated the time interval during which the target was most likely to appear. Temporal-orienting effects were defined by lower reaction times (RTs) when there was a match between the temporal expectancy for a target (early or late) and the time interval during which the target actually appeared than when they mismatched. Temporal-orienting effects were found for both early and late expectancies with a detection task in Experiment 1. However, catch trials were decisive in whether temporal-orienting effects were observed in the early-expectancy condition. No temporal-orienting effects were found in the discrimination task. In Experiments 2A and 2B, temporal-orienting effects were observed in the discrimination task; however, they were larger when temporal expectancy was manipulated between blocks, rather than within blocks.     

Performance of able-bodied subjects on a text-typing task using a head-operated device and expanded membrane cursor keys

Children and adults with disabilities frequently rely on computers to complete written tasks. Those with significant motor limitations typically use alternative computer-input devices since the traditional keyboard and mouse are insufficient to accommodate their abilities. For persons unable to isolate their fingers, input devices controlled by movements of the head or whole hand or arm movements may be among the options considered. This study investigated the performance of a head-operated device and expanded membrane cursor keys for text entry. Data from 24 young adults indicated the head-operated device performed significantly faster given reduced cognitive demands for device operation, increased stimulus-response compatibility, and simplicity of movement. Use of the expanded membrane cursor keys resulted in significantly lower error rates. No significant differences in comfort or ease of use were reported for the two devices. The relative performance of device options for users sharing similar motor challenges provides rehabilitation specialists with important clinical information.