ray matter deficits and resting-state abnormalities in abstinent eroin-dependent individuals

Previous neuroimaging studies have demonstrated both structural and functional damages in heroindependent individuals. However, few studies investigated gray matter deficits and abnormal resting-state networks together in heroin-dependent individuals. In the present study, voxel-based morphometry (VBM) was used to identify brain regions with gray matter density reduction. Resting-state fMRI connectivity analysis was employed to assess potential functional abnormalities during resting-state. All clinical significances were investigated by examining their association with duration of heroin use. Compared with healthy subjects, heroin-dependent individuals showed significant reduction in gray matter density esting-state in the right dorsolateral prefrontal cortex (DLPFC) and a decrease in resting-state functional connectivity between the right DLPFC and left inferior parietal lobe (IPL). The gray matter density of the right DLPFC and its resting-state functional connectivity with the left IPL both showed significantly negative correlation with duration of heroin use, which were likely to be related to the functional impairments in decision-making and cognitive control exhibited by heroin-dependent individuals. Our findings demonstrated that long heroin dependence impairs the right DLPFC in heroin-dependent individuals, including tingstructural deficits and res rug addiction is conceptualized as a syndrome of impaired esponse inhibition and salience attribution, characterized by ompulsive drive to take drugs despite of serious negative conequences [11]. Emerging morphometry studies have reported tructural deficits in heroin-dependent individuals, such as heroinependent individuals exhibited increased white matter intensity n the frontal area and decreased gray matter density in the ilateral prefrontal cortices and in the temporal regions as comared with healthy subjects [18,19,28]. Recently, Yuan et al. 28] showed that gray matter density of the prefrontal, tempoal and cingulate cortices in heroin-dependent individuals was egatively correlated with the duration of heroin use. However, he authors failed to investigate the resting-state abnormalities f these abnormal structural brain regions in heroin-dependent ndividuals. ∗ Corresponding author at: Institute of Automation, Chinese Academy of Sciences, . O. Box 2728, Beijing 100190, China. Tel. : +86 10 62527995; fax: +86 10 62527995. E-mail address: tian@ieee.org (J. Tian). 304-3940/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. oi:10.1016/j.neulet. 2010.07. 005 state functional impairments. © 2010 Elsevier Ireland Ltd. All rights reserved. In addition, functional impairments in heroin-dependent individuals have also been verified by employing task-related fMRI methods [9,15,25]. Numerous neuroimaging studies have revealed impaired response inhibition function and decision-making function in heroin-dependent subjects by presenting hypoactivation of the prefrontal and rostral anterior cingulate cortex (ACC) in certain tasks [9,15,25]. Although fMRI task-related studies can investigate specific functional disturbances in heroin-dependent individuals, assessment of resting-state functional networks may have different and potentially broader significance. Resting-state functional connectivity analysis has been utilized to investigate the integration level of neural systems when no explicit task was engaged and the results demonstrated correlated spontaneous activity occurring within spatially distinct, functionally related groups of brain regions during task-free conditions [7,8,12]. Recently, assessments of resting-state networks have also been conducted in heroin addiction [16,20,26]. Ma et al. [20] adopted the seed-based regions of interest (ROIs) correlation analysis method and observed alteration in resting-state brain connectivity in heroin-dependent individuals, i.e. increased functional connectivity between the nucleus accumbens (NAc) and ACC, the NAc and orbitofrontal cortex 1 ce Letters 482 (2010) 101–105 ( t c y a i o n p c s p d a d v m i t t v o t t R l a y r t M n t u o t d e i p d d d o s h t d p o p w [ r 2 u o i w N fi a a h Table 1 Demographic and clinical characteristics of heroin-dependent individuals and