Abstract
ObjectiveThis study aimed to explore the functional connectivity of the default mode network (DMN) in crack-cocaine users, in comparison with that observed in age-matched non-drug-using controls.Materials and MethodsInpatient crack-cocaine users who had been abstinent for at least four weeks and age-matched non-drug-using controls underwent resting state functional magnetic resonance imaging. Images were acquired while the subjects rested with their eyes closed. After data preprocessing, DMNs were defined by spatial independent component analysis and seed-based correlation analysis, by chosen regions of interest centered in the ventral anterior cingulate cortex and in the posterior cingulate cortex.ResultsThe functional connectivity of the DMN determined by independent component analysis did not differ between the crack-cocaine users and the controls. However, the seed-based correlation analysis seeking a single metric of functional connectivity between specific brain regions showed that the negative connectivity between the ventral anterior cingulate cortex and the left superior parietal lobule was significantly greater in the crack-cocaine users than in the controls.ConclusionThe results suggest that selective extrinsic network connectivity of the DMN related to motor and executive function is impaired during crack-cocaine addiction.
Highlights
Crack-cocaine has emerged as a substance that readily supplies the active principle through the inhalation of smoke from burning rocks of the substance, typically by means of a pipe[1]
According to Volkow et al[4], there are four interrelated circuits that are involved in or affected by drug addiction: the reward circuit—involving several nuclei in the basal ganglia, notably the nucleus accumbens of the ventral striatum, and relaying information to the ventral pallidum; the motivation/drive circuit—involving the orbitofrontal and subcallosal cortices, dorsal striatum, and motor cortex; the learning/memory circuit— involving the amygdala and the hippocampus; and the control circuit—which controls cognitive flexibility and planning, involving the dorsolateral prefrontal cortex, anterior cingulate cortex, and inferior frontal cortex. Many of these brain structures are associated with the default mode network (DMN)(5–7), one of the brain networks seen in resting state functional magnetic resonance imaging studies[8]
The DMN is composed of brain regions that are typically deactivated during task demands but exhibit synchronous low frequency oscillation in the resting state[6,7,9]
Summary
Crack-cocaine has emerged as a substance that readily supplies the active principle (cocaine) through the inhalation of smoke from burning rocks of the substance, typically by means of a pipe[1]. According to Volkow et al[4], there are four interrelated circuits that are involved in or affected by drug addiction: the reward circuit—involving several nuclei in the basal ganglia, notably the nucleus accumbens of the ventral striatum, and relaying information to the ventral pallidum; the motivation/drive circuit—involving the orbitofrontal and subcallosal cortices, dorsal striatum, and motor cortex; the learning/memory circuit— involving the amygdala and the hippocampus; and the control circuit—which controls cognitive flexibility and planning, involving the dorsolateral prefrontal cortex, anterior cingulate cortex, and inferior frontal cortex Many of these brain structures are associated with the default mode network (DMN)(5–7), one of the brain networks seen in resting state functional magnetic resonance imaging (rs-fMRI) studies[8]. This provides a new perspective on brain function by addressing the importance of ongoing or intrinsic activity[7]
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