Central executive system impairment in traumatic brain injury

The aim of the present study was to identify cognitive functions affected by traumatic brain injury (TBI) and to verify the mechanism underlying cognitive impairment. More precisely, cognitive deficits following TBI can be considered as a consequence of (a) a speed processing deficit, that is a general slowing of perceptual, motor and cognitive subroutines; (b) an impairment of the Central Executive System of working memory (CES).Thirty-seven patients were submitted to a neuropsychological battery, aimed to evaluate different cognitive functions.Results showed severe deficits in speed processing, divided attention,working memory, executive functions and long term memory.Regression analyses, performed to test the two hypotheses, showed that the working memory deficit hypothesis is able to explain divided attention, executive functions and long term memory deficits more than speed processing hypothesis.     

Influence of mild cognitive impairment on visual word recognition

The present study examined the effects of normal aging and mild cognitive impairment (MCI) on visual word recognition. Madden et al. (1999) reported evidence of general slowing of cognitive processes in Alzheimer's disease (AD) patients relative to younger adults and healthy older adults using a lexical decision task. It was of interest to determine whether similar effects would be observed in MCI patients relative to healthy younger and older adults. We extended the lexical decision task paradigm developed by Allen et al. (2004b) on younger adults to an examination of the effect(s) of MCI on visual word recognition. Results from the present study showed that healthy older adults and MCI patients performed similarly. That is, both groups took longer than younger adults to process words presented in mixed-case than in consistent-case letters. Mild cognitive impairment patients, however, responded significantly more slowly than healthy older adults across all lexical decision task conditions and showed a trend toward larger case-mixing effects than healthy older adults, which suggests that MCI may result in poorer analytic processing ability. Based on the current findings, evidence of a generalized slowing of cognitive processes using a standard lexical decision task can be expanded to include not only AD patients, but also the preclinical stages of the disease as well.     

Impairments of attention following childhood traumatic brain injury.

Attentional deficits are commonly reported following traumatic brain injury (TBI) in adults, although the occurrence of such problems is less well documented in young children. This study aimed to investigate residual attentional abilities associated with TBI during childhood, by examining a number of aspects of attention including sustained, focussed, and divided attention, attentional shift, and response inhibition. Eighteen children with a history of TBI, aged between 8 and 14 years and 18 non-injured matched controls participated in the study. Results show that attentional skills may be differentially impaired after TBI, with children who have sustained moderate-to-severe TBI exhibiting significant deficits on the following attentional domains: sustain, focus, and response inhibition. These findings support the view that attentional impairments following pediatric TBI, while not global, may be more generalized than those reported for adult samples, perhaps reflecting the relative immaturity of attentional skills at the time of injury.     

Development of visual working memory precision in childhood

Visual working memory (VWM) is the facility to hold in mind visual information for brief periods of time. Developmental studies have suggested an increase during childhood in the maximum number of complete items that can simultaneously be stored in VWM. Here, we exploit a recent theoretical and empirical innovation to investigate instead the precision with which items are stored in VWM, where precision is a continuous measure reflecting VWM resolution. Ninety boys aged 7 to 13 years completed one-item and three-item VWM tasks in which stimuli were coloured bars varying in orientation. On each trial, participants used a rotating dial to reproduce the probed stimulus from memory. Results show linear age-related improvement in recall precision for both one-item and three-item VWM tasks. However, even the youngest age group stored a significant amount of information about all three items on the difficult 3-item VWM task. Importantly, the development of VWM precision was not accounted for by development on a sensorimotor control task. Whereas storage of a single complete item was previously thought to be well within the capacity limitations of the current age range, these results suggest protracted development during childhood and early adolescence in the resolution with which single and multiple items are stored in VWM. Probabilistic modelling of response distribution data suggests that improvement in VWM performance is attributable to a specific decrease in variability of stored feature representations, rather than to a decrease in misbinding or random noise. As such, we highlight a novel, potentially developmentally plausible mechanism that may underlie developmental improvement in VWM performance, independent of any alterations in the maximum number of complete items which can be stored.     

Emotional and autonomic responses to visual traumatic stimuli

A fine-grain analysis of autonomic responses are presented with the purpose of extending the conclusions from a previously published paper (Christianson & Nilsson, 1984) on emotional and memorial responses to traumatic visual stimuli. Control subjects were presented with a series of 18 slides of neutral faces, whereas the experimental subjects were presented with six slides of horrible facial injuries in positions 7–12, interspersed between six slides of neutral faces in the beginning, and six slides of neutral faces at the end of the series. The time course of heart rate (HR) and skin conductance (SC) during stimulus presentation was recorded. These data showed an initial pattern of increase in SC, but not in HR. This pattern was subsequently replaced by a combined increase in both SC and HR. The results are discrepant to previous work and are interpreted as effects of not informing the subjects about the gruesome slides to be presented.     

Attentional processes in young children with congenital visual impairment

The study investigated attentional processes of 32 preschool children with congenital visual impairment (VI). Children with profound visual impairment (PVI) and severe visual impairment (SVI) were compared to a group of typically developing sighted children in their ability to respond to adult directed attention in terms of establishing, maintaining, and shifting attention on toys. The measures of children's sensory‐motor understanding (SMU) and language ability were obtained using the Reynell‐Zinkin scales of mental development. The video‐recordings of these play‐based assessments were coded for three categories of behavioural responses (Establish, Maintain, and Shift). The three groups were matched on verbal comprehension (VC), but differed significantly in their SMU and their chronological age. The groups of children with PVI and SVI were found to be comparable in their ability to establish and maintain attention on objects. Despite a relatively good performance overall both groups scored significantly lower on those skills than children who were sighted. However, with regards to attention shifting, children with PVI showed significantly lower performance than both the children with SVI and the sighted children who were similar on this component. Ability to maintain and shift attention was significantly related to the cognitive ability of children with PVI; however the poorer attentional responses were not confined only to the children with low IQ. The results are discussed in relation to the role of vision, cognitive ability and executive function in attentional processes in children with congenital VI.     

Analyzing the role of culture in shaping American childhood: A twentieth-century case

Widespread beliefs about the nature and functions of children change over time, and affect actual treatment of children within and without the family. Significant changes in beliefs about children developed in the United States from the 1920s onward, with emphasis both on emotional value and on weakness or vulnerability. Increased consumption of expert advice played a key role in this shift, along with cultural translation of new issues concerning child labor and schooling. Key changes occurred in all industrial societies, but American culture generated some distinctive features that continue to show up in the anxieties many parents harbor about children and their effort to intervene on their children's behalf.     

Impact of simulated visual impairment on the cognitive test performance of young adults

Aims. This study investigated the effect of simulated visual impairment on the speed and accuracy of performance on a series of commonly used cognitive tests. Methods. Cognitive performance was assessed for 30 young, visually normal subjects (M=22.0±3.1 years) using the Digit Symbol Substitution Test (DSST), Trail Making Test (TMT) A and B and the Stroop Colour Word Test under three visual conditions: normal vision and two levels of visually degrading filters (Vistech^TM) administered in a random order. Distance visual acuity and contrast sensitivity were also assessed for each filter condition. Results. The visual filters, which degraded contrast sensitivity to a greater extent than visual acuity, significantly increased the time to complete (p<.05), but not the number of errors made, on the DSST and the TMT A and B and affected only some components of the Stroop test. Conclusions. Reduced contrast sensitivity had a marked effect on the speed but not the accuracy of performance on commonly used cognitive tests, even in young individuals; the implications of these findings are discussed.     

Communicative impairment in traumatic brain injury: a complete pragmatic assessment

The aim of the present study was to examine the communicative abilities of traumatic brain injury patients (TBI). We wish to provide a complete assessment of their communicative ability/disability using a new experimental protocol, the Assessment Battery of Communication, (ABaCo) comprising five scales—linguistic, extralinguistic, paralinguistic, context and conversational—which investigate all the main pragmatic elements involved in a communicative exchange. The ABaCo was administered to 21 TBI subjects and to a control group. The results showed that performance by TBI patients was worse than that of controls on all scales; moreover they showed a trend of increasing difficulty in understanding and producing different pragmatic phenomena, i.e., standard communication acts, deceits and ironies, whether such phenomena are expressed through the linguistic or extralinguistic modality.     

Concurrent adaptation to opposite visual distortions: impairment and cue

The present study compared single and dual adaptation to visuomotor rotations in different cueing conditions. Participants adapted either to a constant rotation or to opposing rotations (dual adaptation) applied in an alternating order. In Experiment 1, visual and corresponding postural cues were provided to indicate different rotation directions. In Experiment 2, either a visual or a postural cue was available. In all cueing conditions, substantial dual adaptation was observed, although it was attenuated in comparison to single adaptation. Analysis of switching costs determined as the performance difference between the last trial before and the first trial after the change of rotation direction suggested substantial advantage of the visual cue compared to the postural cue, which was in line with previous findings demonstrating the dominance of visual sense in movement representation and control.     

Hemispheric visual atentional imbalance in patients with traumatic brain injury

We find a spatially asymmetric allocation of attention in patients with traumatic brain injury (TBI) despite the lack of obvious asymmetry in neurological indicators. Identification performance was measured for simple spatial patterns presented briefly to a locus 5 degrees into the left or right hemifield, after precuing attention to the same (ipsilateral) or opposite (cross-hemifield) side. Though the cue was non-predictive of target location overall, performance was significantly slower for cross than for ipsilateral trials in both patients and controls. We tested 21 TBI patients without overt focal brain damage and nine control subjects. Only patients demonstrated significantly worse performance for left side presentation in the ipsilateral condition. Furthermore, in the cross-hemifield condition, the left-right difference seen in TBI patients was significantly larger-reflecting a failure in producing a leftward attention shift. Again no significant difference was found in controls. These hemifield effects suggest an asymmetry in the ability of TBI patients in shifting attention to the left hemifield, whether from central fixation or from a cue in the contra-lateral hemifield. The results support basic hypotheses regarding visual attention: Attentional control may be asymmetric and attention may be a distributed, rather than localized cortical function.     

The development of visual working memory capacity during early childhood

The change detection task has been used in dozens of studies with adults to measure visual working memory capacity. Two studies have recently tested children in this task, suggesting a gradual increase in capacity from 5 years to adulthood. These results contrast with findings from an infant looking paradigm suggesting that capacity reaches adult-like levels within the first year. The current study adapted the change detection task for use with children younger than 5 years to test whether the standard version of the task was too difficult and may have underestimated children's capacity. Results showed that 3- and 4-year-olds could successfully complete this modified task and that capacity increased roughly linearly, from 2 or 3 items during this period to 3 or 4 items between 5 and 7 years. Furthermore, performance did not differ significantly between the modified version and a replication of the standard version with 5- and 7-year-olds. Thus, there is no evidence that previous research with the change detection task underestimated children's capacity. Further research is needed to understand how performance relates across the infant looking task and change detection to provide a more complete picture of visual working memory capacity over development.     

The role of visual attention in predicting driving impairment in older adults

This study evaluated the role of visual attention (as measured by the DriverScan change detection task and the Useful Field of View Test [UFOV]) in the prediction of driving impairment in 155 adults between the ages of 63 and 87. In contrast to previous research, participants were not oversampled for visual impairment or history of automobile accidents. Although a history of automobile accidents within the past 3 years could not be predicted using any variable, driving performance in a low-fidelity simulator could be significantly predicted by performance in the change detection task and by the divided and selection attention subtests of the UFOV in structural equation models. The sensitivity and specificity of each measure in identifying at-risk drivers were also evaluated with receiver operating characteristic curves.     

Dissociations in visual attention deficits among persons with mild cognitive impairment

Impairments in visual attention and visual information processing have been identified as part of the neuropsychological features of Alzheimer's disease (AD), even in its earliest stages. There is increasing recognition that these deficits may be selective rather than global, with some attentional subtypes being more vulnerable than others. The few studies that have investigated attentional deficits in mild cognitive impairment (MCI), a putatively prodromal phase of AD, have not satisfactorily addressed the possible selectivity in attentional deficits in MCI. This study examined potential dissociations in visual attention deficits in MCI using a measure that assesses simple, divided, and selective attention. The results indicated a hierarchy of attentional impairments, with divided attention being the most affected and simple attention the least. Among participants with MCI, 53% showed evidence of impairment in divided attention compared to 19% of controls (OR = 4.81, p < .001). Poorer visual attention was also associated with poorer overall cognitive status. The implications of these findings for early identification of MCI, prevention of functional decline in MCI, and delay/reversal of cognitive degradation in MCI are discussed.     

Developmental impact of frontal lobe injury in middle childhood.

Executive function of frontal lobe systems, like intelligent behavior, appears to demonstrate two major features: it is adaptive and goal-directed. Disruption of executive function following injury to the frontal lobes in childhood might be predicted to impact the trajectory of normal cognitive, behavioral, and social development. Case studies of two children injured at different ages showed the primary developmental impact to involve the behavioral and social realms. While cognitive development may be suspected to also be considerably influenced, assessment of changes in cognitive abilities by traditional psychometric means was found to be problematic. Psychometric changes were found to occur over a prolonged period of time, emphasizing the importance of documenting observations and chronicling postinjury events.     

The impact of auditory distraction on retrieval of visual memories

Recent research has revealed that the presence of irrelevant visual information during retrieval of long-term memories diminishes recollection of task-relevant visual details. Here, we explored the impact of irrelevant auditory information on remembering task-relevant visual details by probing recall of the same previously viewed images while participants were in complete silence, exposed to white noise, or exposed to ambient sounds recorded at a busy café. The presence of auditory distraction diminished objective recollection of goal-relevant details, relative to the silence and white noise conditions. Critically, a comparison with results from a previous study using visual distractors showed equivalent effects for auditory and visual distraction. These findings suggest that disruption of recollection by external stimuli is a domain-general phenomenon produced by interference between resource-limited, top-down mechanisms that guide the selection of mnemonic details and control processes that mediate our interactions with external distractors.     

Academic achievement in Norwegian secondary schools: the impact of violence during childhood

Using data from a national survey (N = 6,979) of young people in their last year in Norwegian secondary schools in 2007 (aged 18 and 19), this paper examines the effect of experience of violence including sexual abuse during childhood (before the age of 13) on the later academic achievement of young people. This investigation includes three types of violence: non-physical, physical and sexual, and two types of victimisation: being abused and witness to abuse. First we investigate the relationship between the experience of various violent acts before the age of 13 and young people??s later academic achievement. Second, applying the structural equation modelling technique, we take into account the effect of background factors such as parents?? educational attainment and gender, and the effect of mediating factors such as social capital and educational motivation on the academic achievement of the young victims. The results show that exposure to violence during childhood not only directly influences young people??s educational outcomes but also exerts indirect influences on their achievement through its impact on young victims?? social relations and psychological health.