Dysfunctional Modulation of Default Mode Network Activity in Attention-Deficit/Hyperactivity Disorder Baris Metin, Ruth M. Krebs, Jan R. Wiersema, Tom Verguts, and Roos Gasthuys Ghent University Jacob J. van der Meere University of Groningen Eric Achten and Herbert Roeyers Ghent University Edmund Sonuga-Barke Ghent University and University of Southampton The state regulation deficit model posits that individuals with attention-deficit/hyperactivity disorder (ADHD) have difficulty applying mental effort effectively under suboptimal conditions such as very fast and very slow event rates (ERs). ADHD is also associated with diminished suppression of default mode network (DMN) activity and related performance deficits on tasks requiring effortful engagement. The current study builds on these 2 literatures to test the hypothesis that failure to modulate DMN activity in ADHD might be especially pronounced at ER extremes. Nineteen adults with ADHD and 20 individuals without any neuropsychiatric condition successfully completed a simple target detection task under 3 ER conditions (2-, 4-, and 8-s interstimulus intervals) inside the scanner. Task-related DMN deactivations were compared between 2 groups. There was a differential effect of ER on DMN activity for individuals with ADHD compared to controls. Individuals with ADHD displayed excessive DMN activity at the fast and slow, but not at the moderate ER. The results indicate that DMN attenuation in ADHD is disrupted in suboptimal energetic states where additional effort is required to optimize task engagement. DMN dysregulation may be an important element of the neurobiological underpinnings of state regulation deficits in ADHD. Keywords: ADHD, default mode network, event rate, fMRI, state regulation deficit Supplemental materials: http://dx.doi.org/10.1037/abn0000013.supp Efficient performance depends on the ability to maintain an optimal energetic state despite changing environmental demands (Sanders, 1983). The performance of individuals with attention- deficit/hyperactivity disorder (ADHD) is hyper-sensitive to exper- imentally induced changes in certain aspects of the task context (see Sonuga-Barke, Wiersema, van der Meere, & Roeyers, 2010 for a review). For instance, task performance in ADHD is dis- rupted at extreme event rates (ERs). A meta-analysis of ER effects on Go/No-Go tasks demonstrated that individuals with ADHD make more impulsive errors under fast ER conditions and respond slower under slow ER conditions (Metin, Roeyers, Wiersema, van der Meere, & Sonuga-Barke, 2012). The state regulation deficit (SRD) model applies the framework of Sanders (Sanders, 1983) to explain these effects in terms of deficient management of energetic resources to maintain optimal task engagement under nonoptimal conditions (Sergeant, 2005). It has been hypothesized that individ- uals with ADHD have a problem in applying the required effort to actively modulate extreme ER-related changes in activation states This article was published Online First October 13, 2014. Baris Metin, Department of Experimental-Clinical and Health Psychology, Ghent University; Ruth M. Krebs, Department of Experimental Psychology, Ghent University; Jan R. Wiersema, Department of Experimental-Clinical and Health Psychology, Ghent University; Tom Verguts, Department of Experimental Psychology, Ghent University; Roos Gasthuys, Department of Experimental- Clinical and Health Psychology, Ghent University; Jacob J. van der Meere, Department of Clinical and Developmental Neuropsychology, University of Gro- ningen; Eric Achten, Department of Radiology, Ghent University; Herbert Roey- ers, Department of Experimental-Clinical and Health Psychology, Ghent Univer- sity; Edmund Sonuga-Barke, Developmental Brain-Behaviour Unit, School of Psychology, University of Southampton and Department of Experimental-Clinical and Health Psychology, Ghent University. Baris Metin is now in the Department of Psychology, Uskudar University. The study presented in this article was conducted at Ghent University, Faculties of Psychology and Medicine. Herbert Roeyers received research support from Shire. Edmund Sonuga-Barke declares the following com- peting interests during the last 3 years—fees for speaking, consultancy, research funding and conference support from Shire; speaker fees from Janssen Cilag, Medice & Obtech, book royalties from Oxford University Press and Jessica Kingsley; conference support from Shire. All other authors report no biomedical financial interests or potential conflicts of interest during the last 3 years. This study was supported by the Fund for Scientific Research-Flanders (grant number G.0310.09N). Correspondence concerning this article should be addressed to Baris Metin, Uskudar University, Department of Psychology, Altunizade Mh., Haluk Turksoy Sk. 14, 34662, Uskudar, I ˙ stanbul, Turkey. E-mail: drbarismetin@ gmail.com This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Journal of Abnormal Psychology © 2014 American Psychological Association 2015, Vol. 124, No. 1, 208 –214 0021-843X/15/$12.00 http://dx.doi.org/10.1037/abn0000013 208