Major depressive disorder (MDD) is a severe, disabling pathology characterized, in addition to affective, cognitive and motor symptoms, by self-focused attention and rumination. During recursive self-focused processes...Major depressive disorder (MDD) is a severe, disabling pathology characterized, in addition to affective, cognitive and motor symptoms, by self-focused attention and rumination. During recursive self-focused processes and rumination, the posterior cingulate cortex (PCC) is activated. In vivo proton magnetic resonance spectroscopy (MRS) is a noninvasive imaging technique that can directly assess living biochemistry in localized brain regions. The aim of this study, therefore, was to use 1H-MRS as a means of analyzing brain metabolites in the PCC of a group of first-episode, unmedicated MDD patients. PCC metabolite levels were analyzed at 3-T in a single voxel located bilaterally over the PCC in 7 patients diagnosed for the first time with MDD and with no previous pharmacological treatment, as well as in 9 control subjects. Differences in metabolite levels between groups were compared using independent t-tests. Myo-inositol was significantly higher, and NAA + NAAG/Cr significantly lower, in MDD patients than in controls. The other brain metabolites showed no statistical differences. The present results suggest that alterations in PCC metabolite levels are likely involved in MDD pathophysiology, and may help to improve our understanding of MDD and the role of the PCC in some symptoms of depression.展开更多
Background Previous animal and neuroimaging studies have demonstrated that brain function in heroin addicted users is impaired. However, the posterior cingulate cortex （PCC） has not received much attention. The purp...Background Previous animal and neuroimaging studies have demonstrated that brain function in heroin addicted users is impaired. However, the posterior cingulate cortex （PCC） has not received much attention. The purpose of this study was to investigate whether chronic heroin use is associated with craving-related changes in the functional connectivity of the PCC of heroin addicted users. Methods Fourteen male adult chronic heroin users and fifteen age and gender-matched healthy subjects participated in the present study. The participants underwent a resting-state functional magnetic resonance imaging （fMRI） scan and a cue-induced craving task fMRI scan. The activated PCC was identified in the cue-induced craving task by means of a group contrast test. Functional connectivity was analyzed based on resting-state fMRI data in order to determine the correlation between brain regions. The relationship between the connectivity of specific regions and heroin dependence was investigated. Results The activation of PCC, bilateral anterior cingulate cortex, caudate, putamen, precuneus, and thalamus was significant in the heroin group compared to the healthy group in the cue-induced craving task. The detectable functional connectivity of the heroin users was stronger between the PCC and bilateral insula, bilateral dorsal striatum, right inferior parietal Iobule （IPL） and right supramarginal gyrus （P 〈0.001） compared to that of the healthy subjects in the resting-state data analysis. The strength of the functional connectivity, both for the PCC-insula （r=0.60, P 〈0.05） and for PCC-striatum （t=0.58, P 〈0.05）, was positively correlated with the duration of heroin use. Conclusion The altered functional connectivity patterns in the PCC-insula and PCC-striatum areas may be regarded as biomarkers of brain damage severity in chronic heroin users.展开更多
基金Lily M.Granados-Dominguez received a grant from CONACYT for graduate studies.
文摘Major depressive disorder (MDD) is a severe, disabling pathology characterized, in addition to affective, cognitive and motor symptoms, by self-focused attention and rumination. During recursive self-focused processes and rumination, the posterior cingulate cortex (PCC) is activated. In vivo proton magnetic resonance spectroscopy (MRS) is a noninvasive imaging technique that can directly assess living biochemistry in localized brain regions. The aim of this study, therefore, was to use 1H-MRS as a means of analyzing brain metabolites in the PCC of a group of first-episode, unmedicated MDD patients. PCC metabolite levels were analyzed at 3-T in a single voxel located bilaterally over the PCC in 7 patients diagnosed for the first time with MDD and with no previous pharmacological treatment, as well as in 9 control subjects. Differences in metabolite levels between groups were compared using independent t-tests. Myo-inositol was significantly higher, and NAA + NAAG/Cr significantly lower, in MDD patients than in controls. The other brain metabolites showed no statistical differences. The present results suggest that alterations in PCC metabolite levels are likely involved in MDD pathophysiology, and may help to improve our understanding of MDD and the role of the PCC in some symptoms of depression.
基金This research was supported-in part by grants from the National Natural Science Foundation of China （Nos. 30870685, 81071142, 81071143 and 81201081） and the Development Project of Science and Technology of Shaanxi Province （Nos. 2008K12-02, 2009K01-65, 2010K16-03-01 and 2010K16-03-02）.
文摘Background Previous animal and neuroimaging studies have demonstrated that brain function in heroin addicted users is impaired. However, the posterior cingulate cortex （PCC） has not received much attention. The purpose of this study was to investigate whether chronic heroin use is associated with craving-related changes in the functional connectivity of the PCC of heroin addicted users. Methods Fourteen male adult chronic heroin users and fifteen age and gender-matched healthy subjects participated in the present study. The participants underwent a resting-state functional magnetic resonance imaging （fMRI） scan and a cue-induced craving task fMRI scan. The activated PCC was identified in the cue-induced craving task by means of a group contrast test. Functional connectivity was analyzed based on resting-state fMRI data in order to determine the correlation between brain regions. The relationship between the connectivity of specific regions and heroin dependence was investigated. Results The activation of PCC, bilateral anterior cingulate cortex, caudate, putamen, precuneus, and thalamus was significant in the heroin group compared to the healthy group in the cue-induced craving task. The detectable functional connectivity of the heroin users was stronger between the PCC and bilateral insula, bilateral dorsal striatum, right inferior parietal Iobule （IPL） and right supramarginal gyrus （P 〈0.001） compared to that of the healthy subjects in the resting-state data analysis. The strength of the functional connectivity, both for the PCC-insula （r=0.60, P 〈0.05） and for PCC-striatum （t=0.58, P 〈0.05）, was positively correlated with the duration of heroin use. Conclusion The altered functional connectivity patterns in the PCC-insula and PCC-striatum areas may be regarded as biomarkers of brain damage severity in chronic heroin users.
