Joshua B. Ewen

Working memory influences processing speed and reading fluency in ADHD

Processing-speed deficits affect reading efficiency, even among individuals who recognize and decode words accurately. Children with ADHD who decode words accurately can still have inefficient reading fluency, leading to a bottleneck in other cognitive processes. This “slowing” in ADHD is associated with deficits in fundamental components of executive function underlying processing speed, including response selection. The purpose of the present study was to deconstruct processing speed in order to determine which components of executive control best explain the “processing” speed deficits related to reading fluency in ADHD. Participants (41 ADHD, 21 controls), ages 9–14 years, screened for language disorders, word reading deficits, and psychiatric disorders, were administered measures of copying speed, processing speed, reading fluency, working memory, reaction time, inhibition, and auditory attention span. Compared to controls, children with ADHD showed reduced oral and silent reading fluency and reduced processing speed—driven primarily by deficits on WISC-IV Coding. In contrast, groups did not differ on copying speed. After controlling for copying speed, sex, severity of ADHD-related symptomatology, and GAI, slowed “processing” speed (i.e., Coding) was significantly associated with verbal span and measures of working memory but not with measures of response control/inhibition, lexical retrieval speed, reaction time, or intrasubject variability. Further, “processing” speed (i.e., Coding, residualized for copying speed) and working memory were significant predictors of oral reading fluency. Abnormalities in working memory and response selection (which are frontally mediated and enter into the output side of processing speed) may play an important role in deficits in reading fluency in ADHD, potentially more than posteriorally mediated problems with orienting of attention or perceiving the stimulus.

Altered Connectivity and Action Model Formation in Autism Is Autism

Internal action models refer to sensory-motor programs that form the brain basis for a wide range of skilled behavior and for understanding others’ actions. Development of these action models, particularly those reliant on visual cues from the external world, depends on connectivity between distant brain regions. Studies of children with autism reveal anomalous patterns of motor learning and impaired execution of skilled motor gestures. These findings robustly correlate with measures of social and communicative function, suggesting that anomalous action model formation may contribute to impaired development of social and communicative (as well as motor) capacity in autism. Examination of the pattern of behavioral findings, as well as convergent data from neuroimaging techniques, further suggests that autism-associated action model formation may be related to abnormalities in neural connectivity, particularly decreased function of long-range connections. This line of study can lead to important advances in understanding the neural basis of autism and, more critically, can be used to guide effective therapies targeted at improving social, communicative, and motor function.

Cortical auditory dysfunction in benign rolandic epilepsy

Purpose: To evaluate cortical auditory function, including speech recognition, in children with benign rolandic epilepsy (BRE).

Inhibition Drives Early Feature-Based Attention

Attention can modulate processing of visual input according to task-relevant features, even as early as approximately 100 ms after stimulus presentation. In the present study, event-related potential and behavioral data revealed that inhibition of distractor features, rather than activation of target features, is the primary driver of early feature-based selection in human observers. This discovery of inhibition consistent with task goals during early visual processing suggests that inhibition plays a much larger role at an earlier stage of target selection than previously recognized. It also highlights the importance of understanding the role of inhibition (in addition to activation) in attention.

Updates and future horizons on the understanding, diagnosis and treatment of Sturge–Weber syndrome brain involvement

Aim  To review recent developments in the understanding, diagnosis, and treatment of Sturge–Weber syndrome (SWS).

Quantitative EEG asymmetry correlates with clinical severity in unilateral Sturge-Weber syndrome.

Summary:  Purpose: Sturge‐Weber syndrome (SWS) is a neurocutaneous disorder with vascular malformations of the skin, brain, and eye. SWS results in ischemic brain injury, seizures, and neurologic deficits. We hypothesized that a decrease in quantitative EEG (qEEG) power, on the affected side, correlates with clinical severity in subjects with SWS.

The Disrupted Connectivity Hypothesis of Autism Spectrum Disorders: Time for the Next Phase in Research

During the past decade, the disrupted connectivity theory has generated considerable interest as a pathophysiological model for autism spectrum disorders (ASD). This theory postulates that deficiencies in the way the brain coordinates and synchronizes activity amongst different regions may account for the clinical symptoms of ASD. This review critically examines the current structural and functional connectivity data in ASD and evaluates unresolved assumptions and gaps in knowledge that limit the interpretation of these data. Collectively, studies very often show group alterations in what are thought of as measures of cerebral connectivity, though the patterns of findings vary considerably. We argue that there are three principle needs in this research agenda. First, further basic research is needed to understand the links between measures commonly used (DTI, fMRI, EEG) and other (histological, computational) levels of analysis. Second, speculated causes of inconsistencies in the literature (age, clinical heterogeneity) demand studies that directly evaluate these interpretations. Finally, the field needs well-specified mechanistic models of altered cerebral communication in ASD whose predictions can be tested on multiple levels of analyses.

Use of quantitative EEG in infants with port-wine birthmark to assess for Sturge-Weber brain involvement.

OBJECTIVE Many infants born with a facial port-wine (PW) birthmark will not develop brain involvement of Sturge-Weber syndrome (SWS). Previous studies have shown asymmetry in quantitative EEG (qEEG) correlates with degree of clinical impairment in children and adults with known SWS. We hope to determine if quantitative qEEG can be used as a method to predict which infants are most likely to develop SWS brain involvement on MRI. The current study looks at the ability of qEEG to differentiate between infants with radiographically demonstrated SWS and those without. METHODS We first performed an observational study of qEEG results on eight infants with facial PW birthmark (four had SWS brain involvement). We recorded standard clinical EEGs and then derived a measure of asymmetry. We subsequently validated this threshold through a study of an additional nine infants with PW birthmark (five with SWS brain involvement). RESULTS Quantitative EEG correctly identified infants with SWS brain involvement in all cases in the Validation cohort. This technique was at least as good as a pediatric electroencephalographer with extensive experience reading SWS EEGs. CONCLUSIONS This study demonstrates the ability for qEEG to discriminate between those infants with SWS brain involvement and those with neurologically asymptomatic PW birthmark. SIGNIFICANCE This study represents an important step toward the development of a qEEG technique able to predict which infants with PW birthmark will develop SWS brain involvement.

EEG evolution in Sturge-Weber syndrome

The EEG in Sturge-Weber syndrome (SWS) was theorized over 50 years ago as changing over time from normality to focal asymmetry to lastly epileptiform. We sought to validate these findings in a larger cohort today. Children with confirmed SWS and routine EEG at our center were evaluated retrospectively. An EEG score (0-3) was created and linked to patient current age, overall neurologic function, and seizure frequency. Eighty-one EEGs from 44 patients with SWS (mean age 2.0 years (range: 0.2-37.9 years)) were evaluated and assigned an EEG score. The mean age for patients with an EEG score of 0-1 (normal or focal slowing) was 3.2 years (SEM 0.6), whereas those with an EEG score of 2-3 (focal sharp waves or frequent spike-wave bursts) was 8.7 years (SEM 1.7) (p=0.006). There was no correlation between the EEG score and either the SWS overall neuroscore or seizure subscore (measuring frequency). The EEG in patients with SWS does appear to evolve over time, becoming more abnormal with more frequent epileptiform activity, as suspected in smaller studies decades ago. This progressive change, however, did not correlate with the childs neurologic function or seizure frequency.

Decreased Modulation of EEG Oscillations in High-Functioning Autism during a Motor Control Task

Autism spectrum disorders (ASD) are thought to result in part from altered cortical excitatory-inhibitory balance; this pathophysiology may impact the generation of oscillations on electroencephalogram (EEG). We investigated premotor-parietal cortical physiology associated with praxis, which has strong theoretical and empirical associations with ASD symptomatology. Twenty five children with high-functioning ASD (HFA) and 33 controls performed a praxis task involving the pantomiming of tool use, while EEG was recorded. We assessed task-related modulation of signal power in alpha and beta frequency bands. Compared with controls, subjects with HFA showed 27% less left central (motor/premotor) beta (18–22 Hz) event-related desynchronization (ERD; p = 0.030), as well as 24% less left parietal alpha (7–13 Hz) ERD (p = 0.046). Within the HFA group, blunting of central ERD attenuation was associated with impairments in clinical measures of praxis imitation (r = −0.4; p = 0.04) and increased autism severity (r = 0.48; p = 0.016). The modulation of central beta activity is associated, among other things, with motor imagery, which may be necessary for imitation. Impaired imitation has been associated with core features of ASD. Altered modulation of oscillatory activity may be mechanistically involved in those aspects of motor network function that relate to the core symptoms of ASD.