Journal of the International Neuropsychological Society (2011), 17, 1143–1152. Copyright E INS. Published by Cambridge University Press, 2011. doi:10.1017/S1355617711001226 Functional Magnetic Resonance Imaging of Working Memory and Response Inhibition in Children with Mild Traumatic Brain Injury Lauren S. Krivitzky, 1 Tresa M. Roebuck-Spencer, 2 Robert M. Roth, 3 Kaitlin Blackstone, 1 Chad P. Johnson, 1 AND Gerard Gioia 1 1 Division of Pediatric Neuropsychology, Department of Psychiatry and Behavioral Sciences, Children’s National Medical Center, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia 2 University of Oklahoma, Norman, Oklahoma 3 Brain Imaging Laboratory, Department of Psychiatry, Dartmouth Medical School, Hanover, New Hampshire (RECEIVED March 24, 2011; FINAL REVISION August 12, 2011; ACCEPTED August 12, 2011) Abstract The current pilot study examined functional magnetic resonance imaging (fMRI) activation in children with mild traumatic brain injury (mTBI) during tasks of working memory and inhibitory control, both of which are vulnerable to impairment following mTBI. Thirteen children with symptomatic mTBI and a group of controls completed a version of the Tasks of Executive Control (TEC) during fMRI scanning. Both groups showed greater prefrontal activation in response to increased working memory load. Activation patterns did not differ between groups on the working memory aspects of the task, but children with mTBI showed greater activation in the posterior cerebellum with the addition of a demand for inhibitory control. Children with mTBI showed greater impairment on symptom report and ‘‘real world’’ measures of executive functioning, but not on traditional ‘‘paper and pencil’’ tasks. Likewise, cognitive testing did not correlate significantly with imaging results, whereas increased report of post-concussive symptoms were correlated with increased cerebellar activation. Overall, results provide some evidence for the utility of symptom report as an indicator of recovery and the hypothesis that children with mTBI may experience disrupted neural circuitry during recovery. Limitations of the study included a small sample size, wide age range, and lack of in-scanner accuracy data. (JINS, 2011, 17, 1143–1152) Keywords: Concussion, Brain, Inhibition, Traumatic brain injury, Cerebellum, Prefrontal cortex, Post concussive symptoms INTRODUCTION Traumatic brain injury (TBI) is an important public health issue in the United States. Pediatric TBI has an estimated annual incidence of 180 cases per 100,000, accounting for over 400,000 hospital visits each year (Kraus, Sivak, & Kucera, 1995; Langlois, Rutland-Brown, & Thomas, 2004). Mild TBI (mTBI) accounts for 80 to 90% of all treated cases (Cassidy et al., 2004). However, current published rates of mTBI may be an underestimate given that many mild injuries go untreated or are otherwise unaccounted for (Cassidy et al., 2004; McCrea, Hammeke, Olsen, Leo, & Guskiewicz, 2004; Williamson & Goodman, 2006). mTBI has been defined by the Centers for Disease Control (CDC) as an injury that occurs when an impact or forceful motion of the head results in a brief alteration of mental status, loss of consciousness less than 30 min (or not at all), and post-traumatic amnesia less than 24 hr. A range of neurobehavioral changes are seen in the first days and weeks after mTBI and include somatic, cognitive, and emotional/behavioral difficulties. Commonly reported somatic and emotional symptoms include headache, dizziness, fatigue, sensitivity to light and noise, difficulty concentrating, trouble remembering, and increased anxiety (Mittenberg, Wittner, & Miller, 1997; Yeates et al., 1999). Cognitive changes typically include problems in attention, speed of processing, working memory, and response inhibi- tion (Babikian & Asarnow, 2009; Levin et al., 2002; Satz et al.,1997). Resolution of these neurobehavioral changes following pediatric TBI can be variable across children and may range from a few hours to days or months. In well-controlled pediatric studies, cognitive and achievement deficits have Correspondence and reprint requests to: Gerard Gioia, Children’s National Medical Center, 15245 Shady Grove Road, Suite 350, Rockville, MD 20852. E-mail: ggioia@cnmc.org 1143