Joshua Ewen

Dr. Joshua Ewen


Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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31 January 2011 in Child Neuropsychology
Verified
Journal Article
Closed access
LJLisa A. Jacobson
Lisa A. Jacobson
MRMatthew Ryan
Matthew Ryan
RMRebecca B. Martin
Rebecca B. Martin
JEJoshua Ewen
Joshua Ewen
SMStewart H. Mostofsky
Stewart H. Mostofsky
EME. Mark Mahone
E. Mark Mahone
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.

5 April 2011 in The Neuroscientist
Verified
Journal Article
Open access
PDF file
SMStewart H. Mostofsky
Stewart H. Mostofsky
JEJoshua Ewen
Joshua Ewen
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.

3 January 2014 in Psychological Science
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Journal Article
Open access
PDF file
JMJeff Moher
Jeff Moher
BLBalaji M. Lakshmanan
Balaji M. Lakshmanan
HEHoward E. Egeth
Howard E. Egeth
JEJoshua Ewen
Joshua Ewen
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.

1 May 2016 in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging
Verified
Journal Article
Closed access
RVRoma A. Vasa
Roma A. Vasa
SMStewart H. Mostofsky
Stewart H. Mostofsky
JEJoshua Ewen
Joshua Ewen

23 December 2011 in Developmental Medicine & Child Neurology
Verified
Journal Article
Open access
PDF file
WLWarren Lo
Warren Lo
DMDouglas A. Marchuk
Douglas A. Marchuk
KBKaren L Ball
Karen L Ball
CJCsaba Juhász
Csaba Juhász
LJLori C Jordan
Lori C Jordan
BWBRAIN VASCULAR MALFORMATION CONSORTIUM NATIONAL STURGE–WEBER SYNDROME WORKGROUP
BRAIN VASCULAR MALFORMATION CONSORTIUM NATIONAL STURGE–WEBER SYNDROME WORKGROUP
Aim  To review recent developments in the understanding, diagnosis, and treatment of Sturge–Weber syndrome (SWS).Method  Members of the Brain Vascular Malformation Consortium Sturge–Weber Syndrome National Workgroup contributed their expertise to review the literature and present promising directions for research.Results  The increasing number of reports dealing with SWS over the last decade reflects progress in the diagnosis and understanding of the neurological involvement. The proliferation of centers and advocacy groups to care for patients with SWS and to stimulate research has aided the development of new insights into the clinical manifestations and the pathophysiology of neurological progression, and the development of novel hypotheses to direct future research. Many key questions remain, but the tools and networks to answer them are being developed.Interpretation  This review summarizes important new knowledge and presents new research directions that are likely to provide further insights, earlier diagnosis, improved treatments, and possibly, prevention of this syndrome.

21 August 2019 in Frontiers in Integrative Neuroscience
Verified
Journal Article
Open access
PDF file
JEJoshua Ewen
Joshua Ewen
JSJohn A. Sweeney
John A. Sweeney
WPWilliam Z. Potter
William Z. Potter
Biological treatment development for syndromal neuropsychiatric conditions such as autism has seen slow progress for decades. Speeding drug discovery may result from the judicious development and application of biomarker measures of brain function to select patients for clinical trials, to confirm target engagement and to optimize drug dose. For neurodevelopmental disorders, electrophysiology (EEG) offers considerable promise because of its ability to monitor brain activity with high temporal resolution and its more ready application for pediatric populations relative to MRI. Here, we discuss conceptual/definitional issues related to biomarker development, discuss practical implementation issues, and suggest preliminary guidelines for validating EEG approaches as biomarkers with a context of use in neurodevelopmental disorder drug development.