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Cocaine administration decreases functional connectivity in human primary visual and motor cortex as detected by
1Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226, USA. sjli@mcw.edu
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.
Insights
Cocaine significantly reduces functional connectivity in the visual and motor cortex by 50% and 43%, respectively. These findings in functional magnetic resonance imaging (fMRI) suggest altered neuronal activity in long-term users.
Area of Science:
- Neuroscience
- Radiology
- Pharmacology
Background:
- Long-term cocaine use impacts brain function.
- Understanding cocaine's physiological effects is crucial for addiction research.
Purpose of the Study:
- To investigate the effects of acute cocaine administration on resting-state functional connectivity using fMRI.
- To quantify changes in brain activity in response to cocaine in specific cortical regions.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was performed on seven long-term cocaine users.
- Data acquired using T2*-weighted echo-planar imaging (EPI) under rest, saline, and cocaine conditions.
- Cross-correlation and spatial correlation coefficient (SCC) analyses were used to assess functional connectivity.
Main Results:
- Cocaine administration led to a 50% reduction in SCC in the primary visual cortex.
- A 43% reduction in SCC was observed in the primary motor cortex.
- These reductions indicate significant alterations in neuronal activity.
Conclusions:
- Acute cocaine administration markedly decreases functional connectivity in visual and motor cortices.
- Resting-state fMRI signal changes after cocaine may serve as a baseline for future studies.
- Findings highlight cocaine's impact on brain network function.