Prospective memory and pediatric traumatic brain injury: effects of cognitive demand.

This study investigated the effects of pediatric traumatic brain injury (TBI) on prospective memory. Fourteen children and 14 adolescents with TBI were compared with 25 and 23 noninjured children and adolescents, respectively. Based on a prefrontal model, the cognitive demand on the ongoing component of a prospective-memory task was manipulated. Overall, those with TBI had poorer prospective-memory performance than their noninjured peers. Performance was worse in a high cognitive-demand condition than a low, and younger children performed worse than adolescents. Decreases in performance from the low- to high-demand conditions were not significantly different between the two children's groups but were between the two adolescents' groups. Furthermore, the age and injury effects were reflected in the performances on executive function tests: the Self-ordered Pointing Task (SOPT), and the Stroop Color Word Interference Test. The Tower of London (TOL), which did not produce age or injury effects, was nevertheless found to be an important predictor of performance on the high-demand task in those with TBI. Although previous research has demonstrated impaired prospective memory performance in children with TBI, this study attempted to explain why this might occur, specifically that the prefrontal regions might be implicated.     

Prospective Memory and Pediatric Traumatic Brain Injury: Effects of Cognitive Demand

This study investigated the effects of pediatric traumatic brain injury (TBI) on prospective memory. Fourteen children and 14 adolescents with TBI were compared with 25 and 23 noninjured children and adolescents, respectively. Based on a prefrontal model, the cognitive demand on the ongoing component of a prospective-memory task was manipulated. Overall, those with TBI had poorer prospective-memory performance than their noninjured peers. Performance was worse in a high cognitive-demand condition than a low, and younger children performed worse than adolescents. Decreases in performance from the low- to high-demand conditions were not significantly different between the two children's groups but were between the two adolescents' groups. Furthermore, the age and injury effects were reflected in the performances on executive function tests: the Self-ordered Pointing Task (SOPT), and the Stroop Color Word Interference Test. The Tower of London (TOL), which did not produce age or injury effects, was nevertheless found to be an important predictor of performance on the high-demand task in those with TBI. Although previous research has demonstrated impaired prospective memory performance in children with TBI, this study attempted to explain why this might occur, specifically that the prefrontal regions might be implicated.     

Are People Successful at Learning Sequences of Actions on a Perceptual Matching Task?

We report the results of an experiment in which human subjects were trained to perform a perceptual matching task. Subjects were asked to manipulate comparison objects until they matched target objects using the fewest manipulations possible. An unusual feature of the experimental task is that efficient performance requires an understanding of the hidden or latent causal structure governing the relationships between actions and perceptual outcomes. We use two benchmarks to evaluate the quality of subjects' learning. One benchmark is based on optimal performance as calculated by a dynamic programming procedure. The other is based on an adaptive computational agent that uses a reinforcement-learning method known as Q-learning to learn to perform the task. Our analyses suggest that subjects were successful learners. In particular, they learned to perform the perceptual matching task in a near-optimal manner (i.e., using a small number of manipulations) at the end of training. Subjects were able to achieve near-optimal performance because they learned, at least partially, the causal structure underlying the task. In addition, subjects' performances were broadly consistent with those of model-based reinforcement-learning agents that built and used internal models of how their actions influenced the external environment. We hypothesize that people will achieve near-optimal performances on tasks requiring sequences of action-especially sensorimotor tasks with underlying latent causal structures-when they can detect the effects of their actions on the environment, and when they can represent and reason about these effects using an internal mental model.     

Hormonal state affects recovery from frontal cortex lesions in adult female rats

Pseudopregnant and normal cycling female Sprague-Dawley rats were trained on a delayed-spatial alternation task. After acquisition training, the subjects received frontal cortex lesions and were subsequently tested for retention. The pseudopregnant animals with lesions were less impaired than their normal cycling counterparts. Learning and retention testing were not affected by hormonal status in the noninjured controls. Histological examination showed that the normal cycling rats with frontal cortex lesions possessed enlarged ventricles, indicating the presence of edema in this surgical group. However, brain tissue of pseudopregnant subjects given the same lesion and sham operates of both hormonal states did not display this characteristic of edema. We speculate that the behavioral and anatomical impairment observed in the normal cycling females with brain injury is due to higher levels of vasopressin, a potent vasoconstrictor synchronized with brain injury in our manipulation.     

Prevalence of traumatic brain injury in an inpatient psychiatric population

This study investigated the prevalence of traumatic brain injury (TBI) in an inpatient psychiatric population. We hypothesized increased prevalence of TBI relative to the general population due to a variety of risk factors observed in psychiatric patients. One hundred (mean age = 34) psychiatric inpatients completed the revised Head Injury Questionnaire. Chart review of 17 subjects reporting injuries established whether injuries were documented in medical records. Sixty-eight percent of this psychiatric population reported one or more injuries in which they were unconscious or dazed. This number is higher than the prevalence in the general population. Injuries were generally of mild to moderate severity; multiple injuries were common. Chart review of 17 subjects reporting TBI indicated that histories of TBI had not been noted in the medical record. Finally, 63% of TBI subjects reported that their injury predated the onset of their psychiatric symptoms. These results suggest a possible role of TBI in psychiatric symptomatology and have implications for psychiatric treatment in this population.     

Beery-Buktenica Developmental Test of Visual-Motor Integration performance in children with traumatic brain injury and attention-deficit/hyperactivity disorder

Evaluation of visuoconstructional abilities is a common part of clinical neuropsychological assessment, and the Beery-Buktenica Developmental Test of Visual-Motor Integration (VMI; K. E. Beery & N. A. Beery, 2004) is often used for this purpose. However, few studies have examined its psychometric properties when used to assess children and adolescents with traumatic brain injury (TBI) or attention-deficit/hyperactivity disorder (ADHD), even though these are among the most common acquired and neurodevelopmental forms of brain dysfunction in children. This study examined the validity of VMI scores in 123 children with TBI and 65 with ADHD. The TBI and ADHD groups performed significantly worse than the standardization sample, obtaining VMI mean scores of 87.2 (SD = 13.7) and 93.5 (SD = 11.27). Previous research has noted decrements in visuoconstructional abilities in TBI but relative sparing in ADHD. To examine the criterion validity of VMI scores, the authors therefore compared these 2 groups. As anticipated, the TBI group performed significantly worse than the ADHD group, but receiver operator characteristic analysis indicated that VMI scores were poor at discriminating between groups. Nonetheless, convergent validity evidence supported interpretation of VMI scores as measuring perceptual organization in both groups. In particular, principal components analysis indicated that VMI total scores loaded with perceptual organization tests from the Wechsler Intelligence Scale for Children, 3rd ed. (WISC-III; D. Wechsler, 1997), and its highest correlation was with the WISC-III Perceptual Organization Index. Also, the VMI correlated significantly with the Grooved Pegboard test for the group with TBI. These findings suggest that VMI scores are sensitive to visuoconstructional and motor deficits in children with developmental and acquired brain dysfunction.     

Perceptual complexity and form class cues in novel word extension tasks: how 4-year-old children interpret adjectives and count nouns

Two experiments examined the role of perceptual complexity, object familiarity and form class cues on how children interpret novel adjectives and count nouns. Four-year-old children participated in a forced-choice match-to-target task in which an exemplar was named with a novel word and children were asked to choose another one that matched the exemplar in either shape or material In experiment 1, 56 children were provided with lexical form class cues suggestive of adjectives. The results of Experiment 1 showed that perceptual complexity and not object familiarity determined whether children made material or shape matches. In Experiment 2, 56 children were provided with lexical form class cues suggestive of count nouns. The results of Experiment 2 showed that neither perceptual complexity nor object familiarity affected children's selections in the matching task. When provided with lexical form class cues suggestive of a count noun, children selected shape matches. Thus the results suggest that the perceptual properties of the objects presented to children coupled with the particular lexical form class cue determine which features of objects children attend to when interpreting novel words.     

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.     

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.     

Comparison in the Development of Categories

Recent research on children's word learning has led to a paradox. Although word learning appears to be a deep source of insight into conceptual knowledge for children, preschoolers often categorize objects on the basis of shallow perceptual features such as shape. The current studies seek to resolve this discrepancy. We suggest that comparing multiple instances of a category enables children to extract deeper relational commonalities among category members. We examine 4-year-olds' categorization behaviors when asked to select a match for a target object (e.g., an apple) between a perceptually similar, out-of-kind object (e.g., a balloon) and a perceptually different category match (e.g., a banana). Children who learn a novel word as a label for multiple instances of the category are more likely to select the category match over the perceptual match. Children who learn a label for only one instance are equally likely to select either alternative. This effect is present even when individual target instances are more perceptually similar to the perceptual choice than to the category choice. We conclude that structural alignment processes may be important in the development of category understanding.     

Application of virtual reality graphics in assessment of concussion.

Abnormal balance in individuals suffering from traumatic brain injury (TBI) has been documented in numerous recent studies. However, specific mechanisms causing balance deficits have not been systematically examined. This paper demonstrated the destabilizing effect of visual field motion, induced by virtual reality graphics in concussed individuals but not in normal controls. Fifty five student-athletes at risk for concussion participated in this study prior to injury and 10 of these subjects who suffered MTBI were tested again on day 3, day 10, and day 30 after the incident. Postural responses to visual field motion were recorded using a virtual reality (VR) environment in conjunction with balance (AMTI force plate) and motion tracking (Flock of Birds) technologies. Two experimental conditions were introduced where subjects passively viewed VR scenes or actively manipulated the visual field motion. Long-lasting destabilizing effects of visual field motion were revealed, although subjects were asymptomatic when standard balance tests were introduced. The findings demonstrate that advanced VR technology may detect residual symptoms of concussion at least 30 days post-injury.     

Late maturation of auditory perceptual learning

Adults can improve their performance on many perceptual tasks with training, but when does the response to training become mature? To investigate this question, we trained 11‐year‐olds, 14‐year‐olds and adults on a basic auditory task (temporal‐interval discrimination) using a multiple‐session training regimen known to be effective for adults. The adolescents all began with performance in the adult range. However, while all of the adults improved across sessions, none of the 11‐year‐olds and only half of the 14‐year‐olds did. The adolescents who failed to learn did so even though the 10‐session training regimen provided twice the number of sessions required by adults to reach asymptotic performance. Further, over the course of each session, the performance of the adults was stable but that of the adolescents, including those who learned, deteriorated. These results demonstrate that the processes that underlie perceptual learning can continue to develop well into adolescence.     

Attention After Pediatric Traumatic Brain Injury: A Multidimensional Assessment

Attentional disturbance is a common complaint after TBI in children and adolescents, however, few studies have assessed post-traumatic attentional functions. The attentional constructs proposed by Mirsky, Anthony, Duncan, Ahearn, and Kellam (1991) provided a multidimensional framework for prospective assessment of late attentional disturbance after mild-moderate (n = 34) and severe (n = 57) traumatic brain injury (TBI). Attention was evaluated from 5 to 8 years after TBI in children ages 0 to 15 years at the time of injury. Children with severe TBI performed more poorly than children with mild-moderate TBI on tests comprising the focus/execute and shift constructs. Younger children scored below older children irrespective of injury severity on the Digit Span subtest and interstimulus interval scores from an adaptive rate continuous performance test reflecting the encode and sustain constructs of Mirsky et al. (1991). Age × Severity interaction effects were found for speeded perceptual-motor tests; scores were reduced following mild-moderate and severe TBI in younger children and following severe TBI in older patients. Results are discussed in terms of the vulnerability of skills in a rapid stage of development to disruption by acquired brain injury.     

Cognitive remediation in pediatric traumatic brain injury

Robinson's (1970) elaborative encoding technique (PQRST) was implemented as the active cognitive intervention strategy to address verbal memory deficits in 2 fourth-grade boys following mild or moderate traumatic brain injury (TBI). A metacognitive reading comprehension technique (Smith & Dauer, 1984) was also implemented for comparison purposes. Single-case methodology was employed using a counter-balanced crossover of the two intervention strategies controlling for the effects of attention. The performance of both boys was significantly better during strategy training with the PQRST technique and approached the performance level of the normal comparison subject. In contrast, the performance of both subjects with TBI remained at, or returned to, baseline levels during the metacognitive intervention. These findings suggest that Robinson's cognitive remediation intervention holds promise in addressing memory and reading comprehension deficits following pediatrie traumatic brain injury. Future research should focus on enhancing generalization and transfer of training to classroom assignments.     

Priming visual face-processing mechanisms: electrophysiological evidence

Accumulated evidence from electrophysiology and neuroimaging suggests that face perception involves extrastriate visual mechanisms specialized in processing physiognomic features and building a perceptual representation that is categorically distinct and can be identified by face-recognition units. In the present experiment, we recorded event-related brain potentials in order to explore possible contextual influences on the activity of this perceptual mechanism. Subjects were first exposed to pairs of small shapes, which did not elicit any face-specific brain activity. The same stimuli, however, elicited face-specific brain activity after subjects saw them embedded in schematic faces, which probably primed the subjects to interpret the shapes as schematic eyes. No face-specific activity was observed when objects rather than faces were used to form the context. We conclude that the activity of face-specific extrastriate perceptual mechanisms can be modulated by contextual constraints that determine the significance of the visual input.     

Concept formation and categorization of complex,asymmetric, and impossible figures

Impossible figures are striking examples of inconsistencies between global and local perceptual structures, in which the overall spatial configuration of the depicted image does not yield a coherent three-dimensional object. In order to investigate whether structural “impossibility” is an important perceptual property of depicted objects, we used a category formation task in which subjects were asked to divide pictures of shapes into groups that seemed most natural to them. Category formation is usually unidimensional, such that sorting is dominated by a single perceptual property, so this task can serve as a measure of which dimensions are most salient. In Experiment 1, subjects received sets of 12 line drawings consisting of six possible and six impossible objects. Very few subjects grouped the figures by impossibility on the first try, and only half did so after multiple attempts at sorting. In Experiment 2, we investigated other global properties of figures: symmetry and complexity. Subjects readily sorted objects by complexity, but seldom by symmetry. In Experiment 3, subjects were asked to draw each of the figures before sorting them, which had only a minimal effect on categorization. Finally, in Experiment 4, subjects were explicitly instructed to divide the shapes by symmetry or impossibility. Performance on this task was perfect for symmetry, but not for impossibility. Although global properties of figures seem extremely important to our perception, the results suggest that some of these cues are not immediately obvious or salient for most observers.     

The neurobiology of adaptive learning in reading: A contrast of different training conditions

fMRI was used to investigate the separate influences of orthographic, phonological, and semantic processing on the ability to learn new words and the cortical circuitry recruited to subsequently read those words. In a behavioral session, subjects acquired familiarity for three sets of pseudowords, attending to orthographic, phonological, or (learned) semantic features. Transfer effects were measured in an event-related fMRI session as the subjects named trained pseudowords, untrained pseudowords, and real words. Behaviorally, phonological and semantic training resulted in better learning than did orthographic training. Neurobiologically, orthographic training did not modulate activation in the main reading regions. Phonological and semantic training yielded equivalent behavioral facilitation but distinct functional activation patterns, suggesting that the learning resulting from these two training conditions was driven by different underlying processes. The findings indicate that the putative ventral visual word form area is sensitive to the phonological structure of words, with phonologically analytic processing contributing to the specialization of this region.     

Multiple sessions of systolic blood pressure biofeedback: Its effects on ability to control systolic pressure during training,after training,and its effects on pulse rate

Seventy-one normotensive subjects participated in four training sessions in which they were either (a) instructed to increase their blood pressure, (b) instructed to decrease their blood pressure, or (c) not instructed to change their blood pressure. The subjects either (a) were provided with biofeedback concerning systolic blood pressure or (b) were not provided with biofeedback concerning systolic blood pressure. After the last training session, subjects participated in a transfer session in which they were again instructed concerning changes in pressure but were not provided with biofeedback. Analyses conducted on data from the training and transfer sessions indicated that subjects who were instructed to increase pressure and given biofeedback to aid them showed higher pressure than subjects in other conditions and that there were no differences among those other conditions; that is, biofeedback was effective for teaching subjects to increase pressure but was not effective for teaching subjects to decrease pressure. Additional training sessions did not add to the effect achieved in the first training session. During training sessions, subjects who were instructed to increase pressure showed higher heart rates than subjects in other conditions. The results raise questions concerning the interpretation of earlier experiments that did not include no-treatment, instructions-only, and attention control conditions.     

STRATEGIES TO INCREASE EXERCISE-REPORT CORRESPONDENCE BY BOYS WITH MODERATE MENTAL RETARDATION: COLLATERAL CHANGES IN INTENTION-EXERCISE CORRESPONDENCE

Correspondence between verbal and nonverbal behavior in an exercise room was taught to 4 13-year-old boys diagnosed with moderate mental retardation. Participants were asked prior to each exercise session which exercise machine(s) they intended to use. No contingencies on stating intentions (promising) were applied. Following the exercise session, participants were asked to say (report) which machine(s) they had used. Following the baseline condition, do-report correspondence training was introduced sequentially across participants. During do-report correspondence training, accurate reporting was reinforced. High rates of both do-report and promise-do correspondence were observed. Data were analyzed via a multiple baseline across subjects design and contingency-space analysis. Results are discussed with regard to observed changes in promise-do correspondence subsequent to observed changes in do-report correspondence.     

Developmental versus sensory deficit effects on perceptual processing in the reading disabled

Thirty children and 5 adults participated in two experiments designed to compare visual processing in normal and reading disabled children. The children were aged 8, 10, and 12 years. In Experiment 1, subjects were asked to detect the temporal order of two briefly presented stimuli. In Experiment 2, subjects sorted cards containing bracket stimuli that did or did not produce perceptual grouping effects. Poor readers required more time to make accurate temporal order judgments and showed stronger perceptual grouping effects. For both good and poor readers, the amount of time necessary to make a correct temporal order judgment decreased, and perceptual grouping effects became weaker with age. However, the magnitude of the difference between the groups did not lessen with age. These results suggest that there are visual processing differences between good and poor readers that do not appear to correct by age 12.