Post-adolescent developmental changes in cortical complexity.

BACKGROUND: Post-adolescence is known to be a period of general maturation and development in the human brain. In brain imaging, volumetric and morphologic cortical grey-matter changes can easily be assessed, but the analysis of cortical complexity seems to have been broadly neglected for this age interval. METHODS: Magnetic resonance imaging (MRI) was used to acquire structural brain images. The study involved 17 adolescents (mean age 14.1 ± 0.27, 11 girls) who were compared with 14 young adults (mean age 24.24 ± 2.76, 7 women) for measures of brain complexity (fractal dimension--FD), grey matter (GM) volume and surface-area of cortical ribbon. FD was calculated using box-counting and Minkowski-Bouligand methods; FD and GM volume were measured for the whole brain, each hemisphere and lobes: frontal, occipital, parietal and temporal. RESULTS: The results show that the adults have a lower cortical complexity than the adolescents, which was significant for whole brain, left and right hemisphere, frontal and parietal lobes for both genders; and only for males in left temporal lobe. The GM volume was smaller in men than in boys for almost all measurements, and smaller in women than in girls just for right parietal lobe. A significant Pearson correlation was found between FD and GM volume for whole brain and each hemisphere in both genders. The decrease of the GM surface-area was significant in post-adolescence for males, not for females. CONCLUSIONS: During post-adolescence there are common changes in cortical complexity in the same regions for both genders, but there are also gender specific changes in some cortical areas. The sex differences from different cortical measurements (FD, GM volume and surface-area of cortical ribbon) could suggest a maturation delay in specific brain regions for each gender in relation to the other and might be explained through the functional role of the corresponding regions reflected in gender difference of developed abilities.

Working Memory Training in Norwegian Children with Cerebral Palsy (CP) Show Minimal Evidence of Near and No Far Transfer Effects.

In children with cerebral palsy (CP), learning disabilities are well documented, and impairments in executive functions, such as attention, inhibition, shifting and working memory, represent significant burdens on patients, their families and the society. The aim of this study was to evaluate whether Cogmed RM working memory training could improve working memory in children with CP and investigate whether increased working memory capacity would generalize to other cognitive functions. Twenty-eight children completed the training and the results were compared to a waitlist control group (n = 32). The results yielded three main findings. First, children with CP improved with practice on trained working memory tasks. Second, the intervention group showed minimal near transfer effects to non-trained working memory tasks. Third, no effects on cognitive and behavioral far transfer measures were found.

Working memory deficit in dyslexia: behavioral and FMRI evidence.

Dyslexia is a condition characterized by difficulty of reading given adequate intelligence and educational opportunities, primarily associated with a phonological processing deficit. In this study we show that dyslexic children also show a deficit in working memory compared to a control group, measured with fMRI. A working memory n-back task with three load levels was used. Behavioral data showed that the dyslexics had poorer performance compared to the controls. fMRI data showed that the dyslexics had reduced activation in the prefrontal and parietal cortices and the cerebellum compared with the controls. These results imply a working memory deficit in dyslexia.

Executive working memory processes in dyslexia: behavioral and fMRI evidence.

Dyslexia is an impairment in learning to read and write, primarily associated with a phonological core deficit. However, the manifestation of symptoms in dyslexia also includes impaired working memory (WM). The aim of this study was to investigate cortical activation related to verbal WM in dyslexic and normal readers aged around 13 years, controlling for phonological awareness processing. We used a modified WM n-back task where the participants remembered the first or last speech segment (phonemes) of the names of common objects shown as pictures. Dyslexic readers were impaired compared with the control group. Compared with the dyslexic readers, controls showed increased fMRI activation in the left superior parietal lobule and the right inferior prefrontal gyrus. Unlike controls, dyslexics did not show a significant increase in activation in WM areas with increased memory load. These findings provide support for a specific working memory deficit in dyslexic individuals.

Dyslexic children show short-term memory deficits in phonological storage and serial rehearsal: an fMRI study.

Dyslexia is primarily associated with a phonological processing deficit. However, the clinical manifestation also includes a reduced verbal working memory (WM) span. It is unclear whether this WM impairment is caused by the phonological deficit or a distinct WM deficit. The main aim of this study was to investigate neuronal activation related to phonological storage and rehearsal of serial order in WM in a sample of 13-year-old dyslexic children compared with age-matched nondyslexic children. A sequential verbal WM task with two tasks was used. In the Letter Probe task, the probe consisted of a single letter and the judgment was for the presence or absence of that letter in the prior sequence of six letters. In the Sequence Probe (SP) task, the probe consisted of all six letters and the judgment was for a match of their serial order with the temporal order in the prior sequence. Group analyses as well as single-subject analysis were performed with the statistical parametric mapping software SPM2. In the Letter Probe task, the dyslexic readers showed reduced activation in the left precentral gyrus (BA6) compared to control group. In the Sequence Probe task, the dyslexic readers showed reduced activation in the prefrontal cortex and the superior parietal cortex (BA7) compared to the control subjects. Our findings suggest that a verbal WM impairment in dyslexia involves an extended neural network including the prefrontal cortex and the superior parietal cortex. Reduced activation in the left BA6 in both the Letter Probe and Sequence Probe tasks may be caused by a deficit in phonological processing. However, reduced bilateral activation in the BA7 in the Sequence Probe task only could indicate a distinct working memory deficit in dyslexia associated with temporal order processing.

Evidence of deviant emotional processing in psychopathy: a FMRI case study.

In this case-report we describe a prototypical criminal psychopath by clinical characteristics and functional magnetic resonance imaging (fMRI). To study emotional disability in psychopathy we compared fMRI-BOLD (blood oxygen level dependent) responses to healthy controls. In a block-design subjects were exposed to drawings of facial expressions alternated with scrambled drawings. Exposure to facial expressions activated brain regions of older origin in the psychopath, whereas all activated regions in controls were neocortical. Our findings support the notion that the processing of emotional stimuli in psychopathy is atypical.

Sex-differences in grey-white matter structure in normal-reading and dyslexic adolescents.

MR images were used to look for brain structure irregularities in adolescent children with dyslexia by use of combined grey and white matter volume measurements and fractal dimension (FD) of the grey-white matter border. The data were collected from 13 dyslexic adolescent (8 boys and 5 girls) that were compared with 18 control subjects (8 boys and 10 girls). The MR images were first segmented, and the volume as well as the FD of the grey/white matter border for the whole brain and for each hemisphere was computed. Changes were found in the measured volumes of both grey and white matter and were best reflected in the ratio of grey/white matter and in FD values, especially in the left hemisphere. The results showed that, although dyslexia is less frequent in women, the structural differences in the brain are more pronounced in their case, pointing to an increased vulnerability of the female brain to morphological changes associated with dyslexia.

Long-term use of methylphenidate in a boy with hypothalamic tumor, drug-resistant epilepsy and ADHD.

•We report the successful treatment of a boy with hypothalamic tumor, gelastic seizures, drug-resistant epilepsy and ADHD•The use of methylphenidate significantly reduced symptoms of ADHD while seizure frequency remained unchanged.

Do children with cerebral palsy benefit from computerized working memory training? Study protocol for a randomized controlled trial.

BACKGROUND: Cerebral palsy (CP) is the most common motor disability in childhood (2 to 3 per 1000 live births), and is frequently accompanied by cognitive impairments and behavioural problems. Children with CP are at increased risk of attention deficit disorder with or without hyperactivity (Attention Deficit Disorder (ADD)/Attention Deficit Hyperactivity Disorder (ADHD)) including working memory deficits. The primary aim of this study is to evaluate if cognitive training may improve working memory in children with CP. METHODS/DESIGNS: The study is an investigator-blinded, randomized controlled trial with a stepped-wedge design that will include 115 schoolchildren with CP. Eligible for participation are children with CP, aged 7 to 15 years, who are able to follow instructions and handle a computer mouse. Exclusion criteria are the presence of photosensitive epilepsy, Gross Motor Function Classification System (GMFCS) level V (most severe CP) (Phys Ther 80: 974-985, 2000) and severe visual or hearing impairments. Following assessment of eligibility and baseline cognitive assessment the participants will be randomized to either cognitive working memory training or treatment-as-usual ('control group'). The intervention is a computer-based working memory training program consisting of 25 daily sessions to be performed over a 5 to 6-week period at home. A neuropsychological assessment will be performed before and 4 to 6 weeks after completed training. When the latter assessment has been completed in the intervention group, the 'control group' will start on the same training program. Both groups will meet for a final neuropsychological assessment six months after completed training by an examiner unaware of group adherence. DISCUSSION: There is limited evidence for the effect of most interventions in children with CP, and evidence is completely lacking for interventions aiming to improve deficits in cognition, learning and behaviour. The proposed multicenter study, will bring forth comprehensive information about cognitive, neuropsychological, and daily-life functioning in children with CP aged between 7 and 15 years. In addition, the study will be the first to evaluate the effects of an intervention method to improve working memory in children with CP. If successful, computer-based working memory training may represent an efficient and cost-effective intervention for this group of children. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02119364.

An fMRI study of working memory for schematic facial expressions.

Functional magnetic resonance imaging (fMRI) was used to examine neuronal activation in relation to increasing working memory load in an n-back task, using schematic drawings of facial expressions and scrambled drawings of the same facial features as stimuli. The main objective was to investigate whether working memory for drawings of facial features would yield specific activations compared to memory for scrambled drawings based on the same visual features as those making up the face drawings. fMRI-BOLD responses were acquired with a 1.5 T Siemens MR scanner while subjects watched the facial drawings alternated with the scrambled drawings, in a block-design. Subjects had to hold either 1 or 2 items in working memory. We found that the main effect of increasing memory load from one to two items yielded significant activations in a bilaterally distributed cortical network consisting of regions in the occipitotemporal cortex, the inferior parietal lobule, the dorsolateral prefrontal cortex, supplementary motor area and the cerebellum. In addition, we found a memory load x drawings interaction in the right inferior frontal gyrus in favor of the facial drawings. These findings show that working memory is specific for facial features which interact with a general cognitive load component to produce significant activations in prefrontal regions of the brain.

Frontoparietal activation during delayed visuospatial recall in patients with epilepsy due to hippocampal sclerosis.

We hypothesized that brain activation during encoding and retrieval of visual material differed between epilepsy patients with hippocampal sclerosis (HS) and healthy controls. Eleven patients with epilepsy and HS and nine age- and education-matched control subjects were tested during functional MRI recording. A three-block design for visuospatial memory encoding and retrieval and an interference interval longer than 1 minute without memory tasks were used. All subjects revealed parietal, occipital, and prefrontal activation patterns during encoding. Interference revealed parietal more than occipital activation, whereas retrieval revealed asymmetrical frontal and parietal activation. Patients demonstrated a relative increase in occipitoparietal versus frontal cortical activation as compared with controls. Memory performance did not differ between patients and controls. The increased activation in occipitoparietal versus frontal areas in the patients suggests cortical reorganization of visuospatial recognition memory in epilepsy patients with HS. The study is limited by other factors that may contribute to the results, for example, antiepileptic drugs, effects of greater cognitive effort allocated in patients than controls, and possibly subclinical epileptic activity. However, normal visuospatial memory performance in our patients with HS suggests successful network plasticity.