DOI 10.1007/s00702-005-0344-y J Neural Transm (2006) 113: 671–684 Oculomotor inhibition in children with and without attention-deficit hyperactivity disorder (ADHD) C. Hanisch, R. Radach, K. Holtkamp, B. Herpertz-Dahlmann, and K. Konrad Department of Child and Adolescent Psychiatry, University Hospital Aachen, Germany Received December 21, 2004; accepted May 21, 2005 Published online August 5, 2005; # Springer-Verlag 2005 Summary. The aim of the present study was to distinguish between a general deficit in oculomotor control and a deficit restricted to inhibitory functions in children with atten- tion deficit hyperactivity disorder (ADHD). In addition, we were interested in differen- tiating between a general inhibition deficit and deficient subfunctions of inhibition. We used a prosaccade task to measure general oc- ulomotor abilities in 22 children with ADHD and in age- and gender-matched healthy controls. A fixation, an antisaccade and a countermanding saccade task were used to measure specific aspects of oculomotor in- hibition. Two major results were obtained: First, our prosaccade task suggests similar saccadic response preparation and saccadic accuracy in the ADHD compared to the con- trol children. Secondly, the fixation and the countermanding saccade task indicate defi- cits on measures of oculomotor inhibition in the ADHD group. While patients were specifi- cally impaired in stopping an already initiated response or in suppressing exploratory sac- cades in a novel situation, inhibition of a pre- potent response was not deficient. Our data thus indicate an underlying impairment in cognitive inhibition in ADHD that has been associated with prefrontal lobe functions. More specifically, as the anterior cingulate gyrus has been associated with the counter- manding saccade task and group differences were most pronounced in this paradigm our data are in line with imaging data stressing the importance of this cortical structure in the pathophysiology of ADHD. Keywords: ADHD, inhibition, oculomotor tasks. Abbreviations ACC Anterior cingulate cortex, ADHD Atten- tion deficit hyperactivity disorder, FBB Par- ent rating of ADHD symptoms, FEF Frontal eye field, SD Standard deviation, SSD Stop signal delay, SRT Saccadic reaction time, SSRT Stop signal reaction time. Introduction Oculomotor paradigms provide a promising methodology for characterizing maturational abnormalities in brain systems associated with neurodevelopmental disorders. During the last years, they have been applied to a num- ber of psychiatric disorders, such as ADHD (Munoz et al., 2003), OCD (Rosenberg et al., 1997), autism (Kemner et al., 2004; Takarae et al., 2004), dyslexia (Ramus, 2003) or tou- rette syndrome (Swenney, 2004, for a review).