Abnormal Brain Default-Mode Network Functional Connectivity in Drug Addicts

Abstract

BackgroundThe default mode network (DMN) is a set of brain regions that exhibit synchronized low frequency oscillations at resting-state, and is believed to be relevant to attention and self-monitoring. As the anterior cingulate cortex and hippocampus are impaired in drug addiction and meanwhile are parts of the DMN, the present study examined addiction-related alteration of functional connectivity of the DMN.MethodologyResting-state functional magnetic resonance imaging data of chronic heroin users (14 males, age: 30.1±5.3 years, range from 22 to 39 years) and non-addicted controls (13 males, age: 29.8±7.2 years, range from 20 to 39 years) were investigated with independent component analysis to address their functional connectivity of the DMN.Principal FindingsCompared with controls, heroin users showed increased functional connectivity in right hippocampus and decreased functional connectivity in right dorsal anterior cingulate cortex and left caudate in the DMN.ConclusionsThese findings suggest drug addicts' abnormal functional organization of the DMN, and are discussed as addiction-related abnormally increased memory processing but diminished cognitive control related to attention and self-monitoring, which may underlie the hypersensitivity toward drug related cues but weakened strength of cognitive control in the state of addiction.

Reduced specialized processing in psychotic disorder: a graph theoretical analysis of cerebral functional connectivity

“…2010; Ma et al. 2011; Ding and Lee 2013). The patient population included 26 patients with a diagnosis other than schizophrenia.…”

Resting-state Abnormalities in Heroin-dependent Individuals

“…Heroin-dependent subjects showed reduced functional connectivity between the dACC and the other DMN's components. This finding may explain the weakening of attentional coordination and self-monitoring (Ma et al, 2011). Reduced functional connectivity has been also reported between the dACC and the superior frontal gyrus .…”

“…Declarative memory is a crucial function for the development of addictive behavior because it automatically stores information about heroin taking . The enhanced activation of the hippocampus within the DMN that has been found in heroin-dependent individuals might underlie the increased sensitivity for heroin-related cues because the abnormal augmentation 20 of memory processing seem to mislead the subject's attention and the self-monitoring (Ma et al, 2011). The altered resting-state brain organization which is characterized by an increased degree was evident in theparahippocampal gyrus (Yuan et al, 2010c) as well as the hippocampus (Liu et al, 2009b).…”

“…Therefore, its decreased functional connectivity with the OFC, DLPFC and the right middle temporal lobe of heroin-dependent individuals justifies the impairments in inhibition and decision control (Yuan et al, 2010a). Furthermore, an enhanced degree has been detected in the rACC of heroin-dependent individuals highlighting the complexity of information transfer (Yuan et al, 2010c).The dorsal ACC constitutes the ACC's cognitive component that is involved both in conflict and error monitoring, as well as in inhibition control (Bush et al, 2000;Ma et al, 2010Ma et al, , 2011. Heroin-dependent subjects showed reduced functional connectivity between the dACC and the other DMN's components.…”

“…The DMN is associated with "introspective" and "self-referential" mental activity , "mentalizing" Frith, 1999, 2003), "autobiographical" self Buckner and Carroll, 2007), "self-projection" (Buckner and Carroll, 2007), "stimulus independent thought" Mason et al, 2007), episodic memory (Greicius et al, 2003;Shannon and Buckner, 2004). Furthermore, it is involved in drug-addiction Ma et al, 2011;Li et al, 2013b). Fox et al (2005) proposed that the DMN, as well as another set of brain regions called the task-positive network organize the human brain.…”