Event-Related fMRI of Inhibitory Control in the Predominantly Inattentive and Combined Subtypes of ADHD

Department of Psychiatry, Mount Sinai School of Medicine, New York, New York 10029, USA.
Journal of neuroimaging: official journal of the American Society of Neuroimaging (Impact Factor: 1.73). 08/2009; 19(3):205-12. DOI: 10.1111/j.1552-6569.2008.00289.x
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To examine the neurophysiological basis for the pronounced differences in hyperactivity and impulsiveness that distinguish the predominantly inattentive type of attention-deficit/hyperactivity disorder (ADHD-PI) from the combined type of the disorder (ADHD-C).
Event-related brain responses to a go/no-go test of inhibitory control were measured with functional magnetic resonance imaging (fMRI) in 11 children with ADHD-C and 9 children with ADHD-PI, aged 7 to 13 years, who were matched for age, sex, and intelligence.
There were no significant group differences in task performance. Children with ADHD-C and ADHD-PI activated overlapping regions of right inferior frontal gyrus, right superior temporal lobe, and left inferior parietal lobe during inhibitory control. However, the magnitude of the activation in the temporal and parietal regions, as well as in the bilateral middle frontal gyrus, was greater in children with ADHD-PI than those with ADHD-C. Conversely, children with ADHD-C activated bilateral medial occipital lobe to a greater extent than children with ADHD-PI.
The results provide preliminary evidence that phenotypic differences between the ADHD-C and ADHD-PI subtypes are associated with differential activation of regions that have previously been implicated in the pathophysiology of ADHD and are thought to mediate executive and attentional processes.

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Available from: Mary V. Solanto, Oct 03, 2015
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    • "Response inhibition as measured by go/no-go tasks has emerged as one of the principal paradigms for studying ADHD (Aron and Poldrack, 2005). Using this task, it has been clearly demonstrated that children (Beauregard and Levesque, 2006; Derefinko et al., 2008; Durston et al., 2003; Inoue et al., 2012; Ma et al., 2012; Monden et al., 2012; Siniatchkin et al., 2012; Smith et al., 2006; Solanto et al., 2009; Vaidya et al., 1998), adolescents (Schulz et al., 2004; Tamm et al., 2004) and adults (Dibbets et al., 2009; Karch et al., 2010; Mulligan et al., 2011; Sebastian et al., 2012; Vasic et al., in press) with ADHD have response inhibition deficits. An extensive review of functional neuroimaging in healthy adults indicates that widespread regions of the frontal cortex, especially the right inferior frontal gyrus (IFG), are associated with response inhibition (Aron and Poldrack, 2005). "
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    ABSTRACT: An objective biomarker is a compelling need for the early diagnosis of attention deficit hyperactivity disorder (ADHD), as well as for the monitoring of pharmacological treatment effectiveness. The advent of fNIRS, which is relatively robust to the body movements of ADHD children, raised the possibility of introducing functional neuroimaging diagnosis in younger ADHD children. Using fNIRS, we monitored the oxy-hemoglobin signal changes of 16 ADHD children (6 to 13 years old) performing a go/no-go task before and 1.5 h after MPH or placebo administration, in a randomized, double-blind, placebo-controlled, crossover design. 16 age-and gender-matched normal controls without MPH administration were also monitored. Relative to control sub-jects, unmedicated ADHD children exhibited reduced activation in the right inferior frontal gyrus (IFG) and middle frontal gyrus (MFG) during go/no-go tasks. The reduced right IFG/MFG activation was acutely nor-malized after MPH administration, but not after placebo administration. The MPH-induced right IFG/MFG activation was significantly larger than the placebo-induced activation. Post-scan exclusion rate was 0% among 16 right-handed ADHD children with IQ > 70. We revealed that the right IFG/MFG activation could serve as a neuro-functional biomarker for monitoring the acute effects of methylphenidate in ADHD children. fNIRS-based examinations were applicable to ADHD children as young as 6 years old, and thus would con-tribute to early clinical diagnosis and treatment of ADHD children.
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    • "The precise role of the right temporal structures in inhibitory control is more difficult to delineate. These areas have been shown to interact with higher level prefrontal regions during inhibitory control tasks (Egner and Hirsch, 2005) and to be modulated in inhibition-related disorders (Tamm et al., 2004; Solanto et al., 2009), but their precise role remains unclear. An alternative account for the role of right temporal areas in FA commission would be their involvement in the processing of the auditory spatial features distinguishing Go from NoGo stimuli in the current task. "
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    ABSTRACT: Inhibitory control refers to the ability to suppress planned or ongoing cognitive or motor processes. Electrophysiological indices of inhibitory control failure have been found to manifest even before the presentation of the stimuli triggering the inhibition, suggesting that pre-stimulus brain-states modulate inhibition performance. However, previous electrophysiological investigations on the state-dependency of inhibitory control were based on averaged event-related potentials (ERPs), a method eliminating the variability in the ongoing brain activity not time-locked to the event of interest. These studies thus left unresolved whether spontaneous variations in the brain-state immediately preceding unpredictable inhibition-triggering stimuli also influence inhibitory control performance. To address this question, we applied single-trial EEG topographic analyses on the time interval immediately preceding NoGo stimuli in conditions where the responses to NoGo trials were correctly inhibited [correct rejection (CR)] vs. committed [false alarms (FAs)] during an auditory spatial Go/NoGo task. We found a specific configuration of the EEG voltage field manifesting more frequently before correctly inhibited responses to NoGo stimuli than before FAs. There was no evidence for an EEG topography occurring more frequently before FAs than before CR. The visualization of distributed electrical source estimations of the EEG topography preceding successful response inhibition suggested that it resulted from the activity of a right fronto-parietal brain network. Our results suggest that the fluctuations in the ongoing brain activity immediately preceding stimulus presentation contribute to the behavioral outcomes during an inhibitory control task. Our results further suggest that the state-dependency of sensory-cognitive processing might not only concern perceptual processes, but also high-order, top-down inhibitory control mechanisms.
    Frontiers in Human Neuroscience 06/2013; 7:238. DOI:10.3389/fnhum.2013.00238 · 2.99 Impact Factor
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    • "Validity of DSM-IV ADHD 18 MRI spectroscopy study reported that ADHD-C had significantly lower metabolism than ADHD-I in the right lenticular nucleus (Sun et al., 2005), and secondary analyses by Solanto et al. (2009) suggested that alerting and orienting processes may be less efficient in children with ADHD-I than children with ADHD-C. "
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    ABSTRACT: Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria for attention deficit/hyperactivity disorder (ADHD) specify two dimensions of inattention and hyperactivity-impulsivity symptoms that are used to define three nominal subtypes: predominantly hyperactive-impulsive type (ADHD-H), predominantly inattentive type (ADHD-I), and combined type (ADHD-C). To aid decision making for DSM-5 and other future diagnostic systems, a comprehensive literature review and meta-analysis of 546 studies was completed to evaluate the validity of the DSM-IV model of ADHD. Results indicated that DSM-IV criteria identify individuals with significant and persistent impairment in social, academic, occupational, and adaptive functioning when intelligence, demographic factors, and concurrent psychopathology are controlled. Available data overwhelmingly support the concurrent, predictive, and discriminant validity of the distinction between inattention and hyperactivity-impulsivity symptoms, and indicate that nearly all differences among the nominal subtypes are consistent with the relative levels of inattention and hyperactivity-impulsivity symptoms that define the subtypes. In contrast, the DSM-IV subtype model is compromised by weak evidence for the validity of ADHD-H after first grade, minimal support for the distinction between ADHD-I and ADHD-C in studies of etiological influences, academic and cognitive functioning, and treatment response, and the marked longitudinal instability of all three subtypes. Overall, we conclude that the DSM-IV ADHD subtypes provide a convenient clinical shorthand to describe the functional and behavioral correlates of current levels of inattention and hyperactivity-impulsivity symptoms, but do not identify discrete subgroups with sufficient long-term stability to justify the classification of distinct forms of the disorder. Empirical support is stronger for an alternative model that would replace the subtypes with dimensional modifiers that reflect the number of inattention and hyperactivity-impulsivity symptoms at the time of assessment. (PsycINFO Database Record (c) 2012 APA, all rights reserved).
    Journal of Abnormal Psychology 05/2012; 121(4). DOI:10.1037/a0027347 · 4.86 Impact Factor
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