<sod>In children with ADHD, there is a general reduction of volume in certain brain structures, with a proportionally greater decrease in the volume in the left-sided [[prefrontal cortex]].<ref name="Malenka ADHD neurosci" /><ref name=Krain2006>{{cite journal |vauthors=Krain AL, Castellanos FX | title = Brain development and ADHD | journal = Clin Psychol Rev | volume = 26 | issue = 4 | pages = 433–444 | date = August 2006 | pmid = 16480802 | doi = 10.1016/j.cpr.2006.01.005 }}</ref> The [[posterior parietal cortex]] also shows thinning in ADHD individuals compared to controls.<ref name="Malenka ADHD neurosci">{{cite book |vauthors=Malenka RC, Nestler EJ, Hyman SE |veditors=Sydor A, Brown RY | title = Molecular Neuropharmacology: A Foundation for Clinical Neuroscience | year = 2009 | publisher = McGraw-Hill Medical | location = New York | isbn = 9780071481274 | pages = 266, 315, 318–323 | edition = 2nd | chapter = Chapters 10 and 13 | quote =Early results with structural MRI show thinning of the cerebral cortex in ADHD subjects compared with age-matched controls in prefrontal cortex and posterior parietal cortex</ref> Other brain structures in the prefrontal-striatal-cerebellar and prefrontal-striatal-thalamic circuits have also been found to differ between people with and without ADHD.<ref name="Malenka ADHD neurosci" /><ref name="pmid22169776" /><ref name="pmid22983386" /><eod>
<sod>In children with ADHD, there is a general reduction of volume in certain brain structures, with a proportionally greater decrease in the volume in the left-sided [[prefrontal cortex]].<ref name="Malenka ADHD neurosci" /><ref name=Krain2006>{{cite journal |vauthors=Krain AL, Castellanos FX | title = Brain development and ADHD | journal = Clin Psychol Rev | volume = 26 | issue = 4 | pages = 433–444 | date = August 2006 | pmid = 16480802 | doi = 10.1016/j.cpr.2006.01.005 }}</ref> The [[posterior parietal cortex]] also shows thinning in ADHD individuals compared to controls.<ref name="Malenka ADHD neurosci">{{cite book |vauthors=Malenka RC, Nestler EJ, Hyman SE |veditors=Sydor A, Brown RY | title = Molecular Neuropharmacology: A Foundation for Clinical Neuroscience | year = 2009 | publisher = McGraw-Hill Medical | location = New York | isbn = 9780071481274 | pages = 266, 315, 318–323 | edition = 2nd | chapter = Chapters 10 and 13 | quote = Dopamine acts in the nucleus accumbens to attach motivational significance to stimuli associated with reward.&nbsp;... It acts in the orbital prefrontal cortex to set a value on rewards&nbsp;... Therapeutic (relatively low) doses of psychostimulants, such as methylphenidate and amphetamine, improve performance on working memory tasks both in normal subjects and those with ADHD. Positron emission tomography (PET) demonstrates that methylphenidate decreases regional cerebral blood flow in the dorsolateral prefrontal cortex and posterior parietal cortex while improving performance of a spatial working memory task. This suggests that cortical networks that normally process spatial working memory become more efficient in response to the drug.&nbsp;... [It] is now believed that dopamine and norepinephrine, but not serotonin, produce the beneficial effects of stimulants on working memory.&nbsp;... stimulants act not only on working memory function, but also on general levels of arousal and, within the nucleus accumbens, improve the saliency of tasks. Thus, stimulants improve performance on effortful but tedious tasks&nbsp;... through indirect stimulation of dopamine and norepinephrine receptors.&nbsp;... Early results with structural MRI show thinning of the cerebral cortex in ADHD subjects compared with age-matched controls in prefrontal cortex and posterior parietal cortex, areas involved in working memory and attention.}}</ref> Other brain structures in the prefrontal-striatal-cerebellar and prefrontal-striatal-thalamic circuits have also been found to differ between people with and without ADHD.<ref name="Malenka ADHD neurosci" /><ref name="pmid22169776" /><ref name="pmid22983386" /><eod>