SAR-39684-the-neurocircuitry-of-illicit-psychostimulant-addiction--an-_020713.pdf

Drug use in addiction which is more tightly regulated

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drug use in addiction, which is more tightly regulated by the DS. 129 Several studies suggest that cocaine addiction results in altered engagement of frontoparietal networks during attentional tasks. 130,131 Recently it was found that cocaine abusers exhibited reduced functional connectivity between the midbrain, where DA neurons are situated, and cortical and subcortical brain regions during an attentional Stroop task that tested the processing of drug and neutral words. 132 Reduced activation in the right parietal cortex, a region involved in attention, during the two-back verbal working memory task was also found in cocaine-dependent males. 133 In a study investigating the neural underpinnings of drug craving, chronic cocaine use was associated with enhanced reactivity to drug-associated cues, paralleled by enhanced connectivity between the left dorsolateral PFC and occipital cortex compared to healthy control subjects. 134 In addition, the OFC was activated significantly more in cocaine users in response to cocaine cues, but not appetitive stimuli. 134 It has also been found that chronic cocaine users demonstrate impaired sensorimotor abilities that are accompanied by abnormal activity in the cortical and subcortical brain areas involved in motor control. 135 Structural effects Cocaine users have reduced subcortical gray-matter density which negatively correlates with impaired performance in psychomotor performance, recognition and working memory, and planning. 136 Interestingly, in a study that included cocaine- and AMPH-dependent subjects, reduced gray-matter volume in the medial OFC was found, which correlated with increased high-risk decisions in a modified gambling task. 137 Likewise, cocaine-dependent subjects demonstrated impaired decision-making on the Iowa gambling task, which correlated with compromised frontal, parietal, and corpus callosum white-matter integrity. 138 In addition, abnormalities in white-matter microstructure underlying the PFC and HPC are associated with chronic METH use, during both late and early abstinence. 139,140 Chronic METH use is also associated with gray-matter deficits in the cingulate and limbic cortices, reduced hippocampal volume, and white-matter hypertrophy in the temporal regions around the HPC. 141 These cortical and hippocampal abnormalities likely contribute to impaired memory performance found in chronic METH users, while white-matter hypertrophy may be related to altered glial changes. 141 Additionally, decreased temporal lobe, but not frontal lobe, volume was found in both AMPH- and cocaine-dependent subjects. 142 Effects on molecular substrates: DA receptors, DAT, and VMAT Postmortem studies Repeated psychostimulant use can alter DA receptor and transporter expression in several brain regions. Most human postmortem studies have focused on DAT expression in submit your manuscript | Dove press Dove press 35 Neurocircuitry of illicit psychostimulant addiction Substance Abuse and Rehabilitation downloaded from by 71.51.178.127 on 08-Aug-2018 For personal use only.
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