The goal of this study is to test a causal neural mechanism of cannabis use-related problem recognition in individuals with severe cannabis use disorder using a non-invasive form of neuromodulation called transcranial magnetic stimulation (TMS). The main question it aims to answer is: -Does manipulating neural activity in the medial orbitofrontal cortex of the brain affect cannabis use-related problem recognition? Researchers will compare three forms of theta burst stimulation (TBS; sham, intermittent, and continuous) in each participant to see if manipulations in neural activity lead to changes in cannabis use-related problem recognition. Participants will complete a screening interview about their mental health and substance use history and complete four in-person laboratory sessions, which involve questionnaires, four brief magnetic resonance imaging (MRI) scans, three TBS sessions, and three electroencephalogram (EEG) sessions. Participants will also be asked to provide urine samples and take saliva and/or breathalyzer tests at some of the lab visits.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
24
For sham TMS, participants will receive a placebo version of either cTBS or iTBS (in a counterbalanced order). To do this, we will use the "placebo" side of the TMS coil, which produces the same sound volume and sequence as active TMS but does not induce neuromodulatory effects due to using the opposite side of the TMS coil as the "active" side TMS coil. To simulate somatosensory effects of active TMS, sham TMS also use superficial stimulation with the same pulse sequence via a small electrode placed on the target region underneath the coil.
Trains consisting of bursts of three stimuli at 50 Hz repeated at 5 Hz frequency delivered at 110% of measured individual motor threshold in 20 x 2-second trains with 8-second intertrain intervals (192 seconds total)
Trains consisting of bursts of three stimuli at 50 Hz repeated at 5 Hz frequency delivered at 110% of measured individual motor threshold in 1 x 40-second train (40 seconds total)
Cerebral blood flow (CBF) in the medial orbitofrontal cortex
Function magnetic resonance imaging (fMRI) will be used to measure cerebral blood flow (CBF) in the medial orbitofrontal cortex (mOFC) using a 3-Tesla magnet. CBF values will be compared within-subject across stimulation conditions.
Time frame: Lab Visits 2 (day 8), 3 (day 15), and 4 (day 22)
Amplitude of neurophysiological responses to self-referential cannabis use-related information
Electroencephalogram (EEG) will be used to measure late positive potential (LPP) amplitudes to personalized auditory statements about cannabis-related positive expectancies and negative consequences, along with neutral stimuli. LPP amplitudes will be compared within-subject across stimulation conditions.
Time frame: Lab Visits 2 (day 8), 3 (day 15), and 4 (day 22)
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