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Cigarette craving and smoking during fMRI: Report on work in progress

Cigarette craving and smoking during fMRI: Report on work in progress. John Monterosso, PhD Dept of Psychiatry. Project Pitch. Imaging technology has been used to delineate substrates of craving for cigarettes. Studies of craving indicate its higher when smoking is imminently expected.

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Cigarette craving and smoking during fMRI: Report on work in progress

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  1. Cigarette craving and smoking during fMRI: Report on work in progress John Monterosso, PhD Dept of Psychiatry

  2. Project Pitch • Imaging technology has been used to delineate substrates of craving for cigarettes. • Studies of craving indicate its higher when smoking is imminently expected. • We hypothesize that the neural signature of craving will be stronger / different when smoking is imminent.

  3. Regions with positive correlations between change in mean craving scores (Urge to Smoke Scale) and change in relative metabolism (P<.005, uncorrected) in the heavy smoker group (n = 20) Hypothesized regions shown include: dorsolateral prefrontal cortex (DLPFC): orbitofrontal cortex (OFC) anterior insula (Ant Ins) bilaterally. Brody et al 2002

  4. Project Pitch • Imaging technology has been used to delineate substrates of craving for cigarettes. • Studies of craving indicate its higher when smoking is imminently expected. • We hypothesize that the neural signature of craving will be stronger / different when smoking is imminent.

  5. Cue reactivity and availability Skin Conductance Craving Carter and Tiffany 2001

  6. Project Pitch • Imaging technology has been used to delineate substrates of craving for cigarettes. • Studies of craving indicate its higher when smoking is imminently expected. • We hypothesize that the neural signature of craving will be stronger / different when smoking is imminent.

  7. Study Design • Healthy smokers • Pre-trained/ pre screened • Abstinent for ~12 h • 2 scan sessions per subject

  8. Activation task • Blocks begin with 24 second video • Background color indicates whether or not they will smoke after the video • E-Q- 2) E-Q+ 3) E+Q- 4) E+Q+ • Following video, 8 second window of 1) Smoke, or 2) Rest • Each video block occurs 3 times per run • Each run occurs 2 times per session • Each subject performs 2 runs

  9. FMRI Methodology • MRI relies primarily on the magnetic signature of hydrogen (tissue types are differentially loaded with H) • FMRI refers to a variety of techniques that acquire images quickly, and that in some way are sensitive to the activity of the brain • Most Common is BOLD…

  10. Blood Oxygenation Level Dependent FMRI • Activity leads to localized increases in blood flow • The increase in blood flow outstrips the increase in its use • Therefore, activity leads to a relative INCREASE in oxygenated blood • BOLD FMRI capitalizes on magnetic differences between oxygenated and deoxygenated blood.

  11. Important Issues with BOLD FMRI • No meaningful absolute measure -- all contrast based (unlike PET) • Signal dropout at interface of tissues that magnetize differently (“susceptibility artifact”) • Time course of blood flow must be taken into account.

  12. Cartoon of HRF T~8 T=0 T~20

  13. Surf with AFNI -- Single subject • Structural scans • T1 Vs T2 weighting • Signal dropout in OFC • Motion -- why it is such a problem • Motion correction • Functional data -- Preliminary support for hypothesis.

  14. What needs to be done • Preprocess -- fix what can be fixed, dump what cannot. • Group analysis (normalization) • Draw regions • Contrast Q+E+ with Q+E- • Time series analyses

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