Daniel Zarabozo

Does literacy have an effect on stick construction tasks

Since constructional apraxia is often concomitant with brain lesions, the study of constructional tasks in the non-brain-damaged population might be useful in helping to disentangle other causal factors. This paper explores the performance of illiterate individuals (N = 29) as compared to that of semiliterates (N = 21) and literates (N = 23) in order to see the effect of reading and writing abilities on constructional tasks. Each participant was asked to construct 4 figures based upon models having varying degrees of complexity. A global criterion of lack of fidelity and several analytic criteria (related to distortion, rotation, and disarticulation errors) were used to evaluate performance. Although illiterates generally made more errors than semiliterates and semiliterates more than literates, only some of these differences were statistically significant. Significant differences were found for lack of global fidelity and disarticulation errors when all 4 figures were considered together. Subtler data emerged with respect to single figures.

TIME REPRODUCTION DISTURBANCES IN ADHD CHILDREN: AN ERP STUDY

Sixteen ADHD children and a control group were asked to reproduce the varying time duration of successively presented visual stimuli. Time estimation was poorer in ADHD children, who showed more impulsive errors. ERPs exhibited similar grand-mean waveforms for both groups during the estimating period, but they were significantly different during the reproducing stage, when an early positive wave over frontal regions characterized the control group, interpreted as memory-guided motor output, followed by a slow negativity probably reflecting an inhibitory motor closure process, both probably involving central executive networks that seem to be improperly activated in ADHD children.

Rapid Automatized Naming and Lexical Decision in Children from an Electrophysiological Perspective

Rapid Automatized Naming (RAN) deficits have been associated with less developed orthographic abilities that may affect lexical decisions. The effects of Spanish-speaking childrens RAN performance on lexical decisions were evaluated by analyzing ERP and behavioral measures. Based upon their naming speed in four RAN tasks, 28 normal IQ, right-handed, 7-year-old children were selected and divided uniformly into two groups: average-naming (AN), and slow-naming (SN). ERPs were obtained during a lexical decision task consisting of 100 strings of four sequentially-presented letters that completed words (50 trials) or pseudowords (also 50 trials). The SN group showed major reading difficulties when compared to the AN group, as well as a significantly lower number of correct responses and slower reaction times in the lexical task. Two main ERP components were observed: parietal N320, interpreted as analogous to N170/N200; and a subsequent P3-like component (P500) with a higher amplitude for pseudowords, which probably reflects higher cognitive demands. Better reading comprehension and fewer misread pseudowords correlated with minor N320 latencies, while lower N320 amplitudes for words correlated with faster reading speeds, lower naming times and fewer errors while reading a text. The present results suggest that naming speed and ERP seem to be valuable in distinguishing early orthographic stored code retrieval abilities through a lexical decision task. Moreover, RAN and ERP emerge as accurate tools for evaluating reading processes in the early stages of reading acquisition.

Effect of chronic iron deficiency on neuropsychological domains in infants.

The aim of this study was to assess the effects of chronic iron deficiency on neuropsychological traits in infants. We established the nutritional iron status and assessed the neuropsychological characteristics of 58 Mexican 14- to 18-month-old infants. The Bayley Scales of Infant Development, preschool language scales and an environmental sound perception task designed expressly for the study, were used. The infants’ mothers were asked to fill out 2 questionnaires concerning their child’s sociodemographic background. Six different neuropsychological domains were analyzed. Results showed that the chronic iron deficiency group did show significantly lower scores on language, environmental sound perception, and motor measures, when compared with infants with normal nutritional iron status at 6 and 14 to 18 months. Our conclusion is that the development of language and motor skills and environmental sound perception appeared to be sensitive to the effects of chronic iron deficiency in infants.

Syntactic Processing in Turner's Syndrome

A significant controversy concerning language development in Turners syndrome has been found. Whereas some authors have observed that girls with Turners syndrome maintain their verbal abilities intact, others have reported significant differences in Wechsler Verbal IQ when compared with normal controls. However, little has been studied about the linguistic characteristics of these patients when using tests to evaluate different linguistic levels. With the aim of assessing syntactic processes, 15 patients with Turners syndrome (aged 8 to 19 years) were compared with 15 healthy girls, matched by age, Wechsler Full-Scale IQ range, type of school (private or public), and school grade. A syntactic processing battery including 11 different subtests was developed. Compared with controls, the participants with Turners syndrome obtained a fewer number of correct answers in most of the subtests and shorter latencies in some of them. We concluded that the subjects with Turners syndrome have difficulties in using syntactic structures. It is suggested that some of these language difficulties are related to disturbances in using spatial-language relationships. (J Child Neurol 2002;17:668-672).

Neuropsychological Impairment in School-Aged Children Born to Mothers With Gestational Diabetes.

The aim of this study was to determine whether school-aged children born to mothers with gestational diabetes show delays in their neuropsychological development. Several key neuropsychological characteristics of 32 children aged 7 to 9 years born to mothers with gestational diabetes were examined by comparing their performance on cognitive tasks to that of 28 children aged 8 to 10 years whose mothers had glucose levels within normal limits during pregnancy. The gestational diabetes group showed low performance on graphic, spatial, and bimanual skills and a higher presence of soft neurologic signs. Lower scores for general intellectual level and the working memory index were also evident. Our results suggest that gestational diabetes is associated with mild cognitive impairment.

Event-related brain potentials in normal children during detection of inverse serial digits

Three inverse serial digit detection tasks were evaluated with event-related brain potentials (ERPs) in 15 11-year-old children to determine how the increase of perceptual or memory demands could modify detection processing. Reaction times were significantly longer for the task that used visual blurring, compared to that with a greater memory demand. Difference-ERPs (target minus non-target conditions) showed three significant parietal components; one earlier positive peak at 162 ms interpreted as an index of working memory load; a same polarity 295 ms peak which probably represents a P3 analogous and a subsequent negative polarity component (520 ms) possibly involved with motor preparation. A fourth difference-component was a frontal positive peak at 680 ms, interpreted as related to task difficulty.

Event-related brain potentials in reading disabled children during an inverse serial digit detection task.

It has been reported that limitations in different components of working memory could underlie reading disabilities. In addition, reading-disabled (RD) children seem to perform worse when digit name processing is required. With the purpose to explore further these assumptions one inverse serial digit detection task was evaluated using event-related brain potentials in fifteen 8-year-old RD children and a control group (CG). CG obtained significantly more correct responses than RD, but had similar reaction times. The experimental task performance significantly correlated with the performance on reading tests. Difference event-related potentials showed a voltage component peaking at 160 ms over frontocentral leads (P160d) that reached significantly higher amplitude in RD group, and was interpreted as an index of the amount of neural resources involved in visual working memory load. The amplitude of P160d significantly correlated with reading speed, the backward digit span and with the experimental task performance. Present results point out that highly demanding working memory tasks reveal behavioral and electrophysiological differences in RD children with respect to healthy controls.