title: Cocaine administration decreases functional connectivity in human primary visual and motor cortex as detected by functional MRI.
abstract: Functional magnetic resonance imaging (fMRI) was conducted to observe the effects of cocaine administration on the physiological fluctuations of fMRI signal in two brain regions. Seven long-term cocaine users with an average age of 32 years and 8 years of cocaine use history were recruited for the study. A T2*-weighted fast echo-planar imaging (EPI) pulse sequence was employed at 1.5 T to acquire three sets of brain images for each subject under three conditions (at rest, after saline injection, and after cocaine injection [0.57 mg/kg]). Cross-correlation maps were constructed using the synchronous, low frequency signal from voxel time courses after filtering respiratory, cardiac, and other physiological noise. A quantitative evaluation of the changes in functional connectivity was made using spatial correlation coefficient (SCC) analysis. A marked 50% reduction in SCC values in the region of primary visual cortex and 43% reduction in SCC values in the region of primary motor cortex were observed after cocaine administration. This significant reduction in SCC values in these cortical regions is a reflection of changes in neuronal activity. It is suggested that the observed changes in low frequency components after acute cocaine administration during a resting, no-task situation may be used as a baseline reference source when assessing the effects of cocaine on task-driven activation or on mesolimbic dopamine pathways.
authors.affiliation: Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226, USA. sjli@mcw.edu
authors.forename: S J
authors.initials: SJ
authors.lastname: Li
authors.forename: B
authors.initials: B
authors.lastname: Biswal
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: R
authors.initials: R
authors.lastname: Risinger
authors.forename: C
authors.initials: C
authors.lastname: Rainey
authors.forename: J K
authors.initials: JK
authors.lastname: Cho
authors.forename: B J
authors.initials: BJ
authors.lastname: Salmeron
authors.forename: E A
authors.initials: EA
authors.lastname: Stein
mesh_terms: D000293:Adolescent; D000328:Adult; D003042:Cocaine / Q000008:administration & dosage*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000187:drug effects* / Q000473:pathology; D012016:Reference Values; D012680:Sensitivity and Specificity; D012965:Sodium Chloride / Q000008:administration & dosage; D019966:Substance-Related Disorders / Q000175:diagnosis / Q000503:physiopathology*; D009435:Synaptic Transmission / Q000187:drug effects*; D014793:Visual Cortex / Q000187:drug effects* / Q000473:pathology
chemical_list: D012965:Sodium Chloride; D003042:Cocaine