A FMRI Study On The Amplitude Of Low-frequency Fluctuation And Functional Connectivity In Resting-state Of Heroin Dependent Individuals

Part One: The Alteration of Low-frequency Amplitude in Heroin Dependence : A Resting State StudyObjective: The compulsive drug use patterns of heroin addicts was associated with the abnormal neural activity, which was the basis of brain neural circuit abnormality in addiction. The previous researches about drug addiction in resting state functional magnetic resonance imaging study mainly focused on the functional connectivity, but the local neuronal activities in resting state caused by heroin abuse was unclear. In this study we explored the characteristics of local neuronal activities in resting state of heroin dependent patients, and observed the relation between the heroin use history and the ALFF alteration, to investigate the neural biological mechanism of drug addiction.Materials and Methods: Seventeen heroin dependents(HD) and 15 normal controls(NC) were recruited according to strict inclusion and exclusion criteria, the gender, age and educational level between groups were matched. f MRI data were acquired on a 3.0T MRI scanner. The imaging data were processed by the REST and DPARSF software, and the ALFF map of each subject was acquired. Two-sample t test was used for group comparisons of AFLL. Then We determined the ‘‘seeding’’ region as the brain regions where the ALFF value changed significantly between HD and NC group. Whithin the HD group, the correlation between the ALFF values in the seeds and the heroin use history, including heroin use duration, accumulated dosage and the daily dosage, were performed by the partial correlation analysis.Results: Compared with NC, the ALFF of HD was obviously increased in the bilateral cerebellum, left superior occipital gyrus and left superior temporal gyrus and decreased in the right caudate, right anterior cingulate cortex(Anterior Cingulate Cortex,ACC), right superior medial frontal cortex(P < 0.01,corrected by Alpha Sim, T = 2.7633,cluster > 16). The ALFF value in the right caudate in HD individuals was negatively correlated with the duration of heroin use(r =- 0.642, P=0.010) and with the heroin daily dosage( r =-0.817, P < 0.001).Conclusion: Chronic heroin dependence caused the extensive ALFF abnormalities in the cortical and subcortical regions of HD, this was the adaptation reaction, and involved in the stimulus-reponse habit reinforcement and the compensating action of inhibitory control and decision-making behavior of cerebellar, which was related to the heroin use history.Part two: Altered Fronto-Striatal and Fronto-Cerebellar Circuits in Heroin-Dependent Individuals: A Resting-State f MRI StudyObjective: The former study found chronic heroin dependence may caused the extensive ALFF abnormalities in resting-state, which may be the basis of the alteration of the neural network in addiction. In this part, we investigated the relationship between the abnormalities of local neural activity and functional organization pattern using the method of functional connectivity(FC), according to the brain regions with changed ALFF in former study.Materials and Method: The regions which shown significant group difference were set as region of interest(ROI), the diameter was 6 mm, then the function connectivity between ROIs and whole brain were analyzed.Results: Compared with NC, the HD group showed reduced functional connectivity between the right caudate and the right superior temporal gyrus, bilateral middle frontal gyrus, right superior frontal gyrus, and left angular gyrus. Instead, an enhanced functional connectivity was found between the right caudate and the right cerebellum. The HD also showed increased functional connectivity of the right d ACC(Dorsal Anterior Cingulate Cortex) with right lingual gyrus, bilateral inferior frontal gyrus, right inferior parietal lobule.( P < 0.01, Alpha Sim corrected, cluster > 16).Conclusion: Chronic heroin dependent patients shown reduced ALFF in some regions and which was along with the dysfunction of functional connectivity in baseline, and the dysfunction of fronto-striatal and fronto-cerebellar circuit, both of which may cast new light on the mechanisms underlying heroin addiction.