Attention modulates hemispheric differences in functional connectivity: Evidence from MEG recordings

The present study examined intrahemispheric functional connectivity during rest and dichotic listening in 8 male and 9 female healthy young adults measured with magnetoencephalography (MEG). Generalized synchronization within the separate hemispheres was estimated by means of the synchronization likelihood that is sensitive to linear as well as non-linear coupling of MEG signals. We found higher functional intrahemispheric connectivity of frontal and temporal areas within the right as compared to the left hemisphere in the lower and higher theta band during rest, and in the lower theta band during dichotic listening. In addition, higher synchronization in the lower theta band correlated with better task performance. In the upper alpha band, hemispheric differences in intrahemispheric connectivity of the frontal regions were found to be modulated by focused attention instructions. That is, attention to the right ear exaggerates the pattern of higher synchroniza

Visuospatial Perception in Children Born Preterm With No Major Neurological Disorders

Objective: Many investigations have found deficits in visuospatial perception in children born preterm, however, it is not clear whether the deficits are specific to visuospatial perception or the consequences of deficits in other functional areas, whic

Relationships between neuropsychological measures of executive function and behavioral measures of ADHD symptoms and comorbid behavior

Objective: The aim of this study was to examine the relationship between executive functions (EFs), as measured by neuropsychological tests, and symptoms of attention deficit hyperactivity disorder (ADHD) and comorbid behavior, as rated by parents and teachers. As intelligence and language ability are important covariates they were also assessed. Method: The sample consisted of 43 children aged 7-11 years who were referred for neuropsychological assessment at a tertiary clinical facility. Most of the children had the diagnosis of ADHD combined or inattentive type. Different aspects of EFs were assessed. Results: EFs were not significantly related to symptoms of ADHD, but only to comorbid symptoms of depression and autistic symptomatology. Language ability rather than EFs best predicted teacher ratings of inattention. Conclusions: The results of the study do not support the EF theory of ADHD. The importance of screening for comorbid language disorders in children referred for ADHD is emphasized. (c) 2006 National Academy of Neuropsychology. Published by Elsevier Ltd. All rights reserved

Does testosterone affect lateralization of brain and behaviour? A meta-analysis in humans and other animal species

Lateralization of brain and behaviour has been the topic of research for many years in neuropsychology, but the factors guiding its development remain elusive. Based on sex differences in human lateralization, four hypotheses have been postulated that suggest a role for androgens, specifically testosterone. With the discovery that lateralization is a fundamental principle in the organization of brain and behaviour among vertebrates, it has now become possible to experimentally test such hypotheses in animal models. The use of different taxa, humans, other mammalian species and birds (with oestradiol and not testosterone involved in sexual differentiation in birds) facilitates to differentiate between the hypotheses. We used meta-analyses for analysing papers that provided sufficient information, and a semi-quantitative approach based on all relevant studies that we extracted from the literature. We tested the predictions of these hypotheses regarding strength and direction of lateralization for motor output, language and visuospatial cognition in these three taxa. We tested for sex differences and early organizational effects of testosterone (both correlative and experimental studies). We found sex differences in the direction of lateralization for non-human mammals (motor biases similar to humans) and in direction and strength in birds (visual cognitive tasks). However, the prediction that prenatal testosterone exposure affects the direction of lateralization was not supported for humans. In birds and non-human mammals, opposite trends were found, with the effect in non-human mammals being opposite to the expectation based on sex differences. None of the four hypotheses was sufficiently supported and more studies, testing a wider array of functions in different taxa while reporting the data more completely are needed

Neuropsychological outcome in chemotherapy-only-treated children with acute lymphoblastic leukemia

Purpose To evaluate neuropsychological functioning over time in children treated for acute lymphoblastic leukemia (ALL) with chemotherapy only. Patients and Methods Forty-nine consecutive patients (median age at first assessment, 6.8 years; range, 4.0 to 11.8 years) treated with intrathecal and systemic chemotherapy were included in a nationwide, prospective-longitudinal, sibling-controlled study. Patients and siblings completed three extensive neuropsychological assessments: at diagnosis, 3 to 6 months after completion of (2-year) treatment and 4.5 years after diagnosis. Assessments included measures of learning, memory, attention, speed, executive functioning, visual-constructive functioning, and fine-motor functioning. Multilevel analyses were applied to evaluate patients' performances over time and to compare patients to 29 siblings (median age of siblings at first assessment, 8.2 years; range, 4.5 to 12.6 years) and to normative data. Results No major differences were found in neuropsychological performance between patients and siblings, with both groups performing mainly in the normal range. The patient group as a whole, however, scored significantly lower than the siblings on complex fine-motor functioning at the last evaluation. Large practice effects were found for both patients and siblings in four of 11 tasks. Patients who uttered physical complaints (ie, pain and/ or tiredness) at the first pretreatment assessment scored significantly lower than siblings on attention and speed at the last two evaluations. Conclusion Despite intensive and potentially neurotoxic treatment, no evident negative, neuropsychological late effects were found 4.5 years after diagnosis, except for effects on complex fine-motor functioning. Both the large practice effects observed and the poorer performances on sustained attention for patients with physical complaints should be reckoned with in prospective, longitudinal neuropsychological research in children

Post-treatment intellectual functioning in children treated for acute lymphoblastic leukaemia (ALL) with chemotherapy-only:A prospective, sibling-controlled study

intellectual functioning (verbal, performance and full-scale IQ) in 43 children treated for acute lymphoblastic leukaemia (ALL) with chemotherapy-only was evaluated in a nationwide, prospective, sibling-controlled study. Intellectual assessment was performed at diagnosis and repeated shortly after cessation of 2 years treatment, including intrathecal and systemic chemotherapy. Using hierarchical regression analysis, patients' and siblings' (n = 27) scores were longitudinally analysed and compared to assess possible changes and differences over time. At both assessments, before and after treatment, patients showed average scores on intelligence tests compared to population norms. Longitudinal analysis and cross-sectional comparisons revealed no significant differences between patients and controls. Young patients showed a small relative decline, albeit not significant, on performance-IQ compared to healthy siblings. Despite intensive and potentially neurotoxic treatment, no evident negative effects on intelligence were found. However, it cannot be precluded that younger patients are at risk for a small decline in PIQ. (c) 2006 Elsevier Ltd. All rights reserved