Pilot fMRI Studies of Aging-Related Effects of THC

Inclusion Criteria: * CNB use within past 2 years and felt "high" when used. * Able to read, speak, and understand English. * Able and willing to provide written informed consent, and willing to commit to the study protocol. Exclusion Criteria: * Current marijuana tolerance, desire to cut down, or cravings to use during periods of abstinence. * Positive screen for drug or alcohol (except CNB) on test day will result in rescheduling the appointment * History of adverse effects with CNB * CNB users who are abstaining * IQ \<80 on the Wechsler Abbreviated Scale of Intelligence * Inability to comprehend written instructions using the WRAT 4 reading achievement test * Pregnant, breastfeeding, and ineffective birth control methods * Unable or unsafe to have an MRI * Serious medical, neuro-ophthalmological, or neurological illness (e.g. cancer, seizure disorders, encephalopathy * History of head trauma with loss of consciousness \> 30 minutes or concussion lasting 30 days * Focal brain lesion seen on structural MRI * Any medical/neurological condition that could compromise neurocognitive performance (e.g. epilepsy, multiple sclerosis, fetal alcohol syndrome) * Anyone deemed unsafe to study personnel for any reason * Hearing loss such that subject cannot hear sounds at the levels (dB) or pitches (Hz) to be used in the study * Significant pain and/or reduced mobility in the arms