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NEURORADIOLOGYORIGINAL ARTICLE PURPOSE We aimed to test the effect of prescan training and orientation in functional magnetic resonance imaging (fMRI) in children with attention deficit hyperactivity disorder (ADHD) and to investigate whether fMRI compliance was modified by state anxiety. METHODSSubjects included 77 males aged 6-12 years; there were 53 patients in the ADHD group and 24 participants in the healthy control group. Exclusion criteria included neurological and/or psychiatric comorbidities (other than ADHD), the use of psychoactive drugs, and an intelligence quotient outside the normal range. Children were individually subjected to prescan orientation and training. Data were acquired using a 1.5 Tesla scanner and an 8-channel head coil. Functional scans were performed using a standard neurocognitive task. RESULTSThe neurocognitive task led to reliable fMRI maps. Compliance was not significantly different between ADHD and control groups based on success, failure, and repetition rates of fMRI. Compliance of ADHD patients with extreme levels of anxiety was also not significantly different. CONCLUSIONThe fMRI compliance of ADHD children is typically lower than that of healthy children. However, compliance can be increased to the level of age-matched healthy control children by addressing concerns about the technical and procedural aspects of fMRI, providing orientation programs, and performing on-task training. In patients thus trained, compliance does not change with the level of state anxiety suggesting that the anxiety hypothesis of fMRI compliance is not supported. Functional magnetic resonance imaging (fMRI), which uses blood oxygen level-dependent contrast, is a noninvasive procedure for imaging regional brain activity. MRI exhibits high spatial resolution; even 1.5 Tesla (T) imaging used in standard clinical practice (spatial resolution of 2-4 mm) yields robust functional signal changes (1). MRI can be performed without the ethical concerns associated with the other available imaging techniques and can thus be used in children and in healthy populations. In healthy volunteers, fMRI has produced reproducible findings across scanning sites and age groups with respect to the localization and development of cognitive processes (2). Its capacity for noninvasive imaging of the brain in vivo during cognitive processing has made fMRI an exciting tool for laboratory research, as well as clinical studies and clinical practices that involve diagnosis, follow-up, and presurgical mapping (3, 4).A disorder that attracts a great deal of attention in children is attention deficit hyperactivity disorder (ADHD). This focused attention is partly due to the high incidence (0.2%-12.2%) of ADHD, which is also the most frequent diagnosis in children referred to child psychiatry departments (5-7). From the neuropsychological point of view, ADHD is associated with deficits in executive functions (8,9). Nevertheless, as the number of theories on the subject demonstrates, ADHD remains an unresolved issue, especially with res...

Aims and objectives: This study assessed bilinguals’ language control (LC) and inhibitory control (IC) performance (switch costs and Stroop effects) simultaneously in the same participants to investigate how these processes influence each other. Design: Seventy-four Turkish-English bilinguals were presented with Turkish (L1) or English (L2) color words printed either in congruent or incongruent ink color and instructed to name the ink color of these words in the presentation language. Stimuli’s language and congruency were either the same as in the previous trial or different. Data and analysis: Reaction times (RTs), switch costs (mean RTs on language repetition subtracted from switch trials), and the Stroop effects (mean RTs on congruent subtracted from incongruent trials) were analyzed using the linear mixed-effect model. Findings: The switch costs were larger on incongruent than congruent, and the Stroop effects were larger on language switch than repetition trials. This means that the LC performance decreased while resolving conflict, and the IC performance decreased during switching language, indicating that these two share a common IC mechanism. However, the switch costs and Stroop effects across L1 and L2 were symmetrical in all conditions, leaving the previous interpretation uncertain. Besides, the Stroop effects were larger when followed by congruent than incongruent trials during language repetition, whereas they were equal during switching. This means that the ability to adjust performance by previous experience was disrupted during language switching. Moreover, for the high-L2 proficiency group, this ability was diminished in language repetition trials too. These results indicate that rather than inhibition, other processes may primarily mediate bilinguals’ LC. Originality: This study provides evidence for how language and inhibitory control influence each other by combining language switching and Stroop paradigms. Furthermore, it investigates the sequential congruency effects (SCE). Significance/implications: This study shows that SCE investigation may provide significant theoretical implications.

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