Sviluppo di metodi di neuroimaging per valutare la neurobiologia della dipendenza

Subjects will briefly see two images side by side on a screen. Immediately after, a dot appears on the left or on the right. The subjects task is to press the left or right button, following the position of the image (left or right). Images can contain food-related items. We will also show short 1-minute food-related movies. Subjects will be asked to fast for three hours before this task begins.

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in the context of fMRI to study blood-oxygenation-level- dependent responses in the brain to sensory stimulation.

In this task subjects will view pictures of various items on the screen in front of them. Subjects will rate the items by how much they would like to have them. Subjects will choose how much they want the item by pressing a button.

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in the context of fMRI to study blood-oxygenation-level- dependent responses in the brain to sensory stimulation.

Subjects will be asked to imagine whether they would receive money now or money later (in the future). The future money option may be several days from now or as far out as 6 weeks from now. For example, a s ubject may see a $100 option in 6 weeks or a $10 option now. Subjects will not receive actual money for participation in this task

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in the context of fMRI to study blood-oxygenation-level- dependent responses in the brain to sensory stimulation.

Subjects will make a choice among some items presented on the screen in front of them. One of the items will be the winner item. The other items will be loser items. Each time a subject is presented with various items, they will choose the item they think is the winner item. Subjects will start with bonus points at the beginning of the task, so they can add more points to this amount as they continue to choose winner items.

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in the context of fMRI to study blood-oxygenation-level- dependent responses in the brain to sensory stimulation.

Electroencephalography or electrooculography (EEG/ EOG) sessions to record electrical activity of the brain or measure corneo-retinal standing potentials.

During the MRI scan, subjects will get small electric shocks through electrodes placed on one of their toes. The shocks feel like an elastic band snapping against the skin. Right after a shock, subjects will see a dot on the computer screen. Subejcts will press a button to rate the intensity of the shock.

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in conjunction with pupillometry in the context of fMRI to study blood-oxygenation-level-dependent responses to selective neurostimulation of pain fibers.

Subjects will identify changes in various shapes when they are displayed on the screen in front of them. Some changes of the shapes may be that they were rotated, enlarged, or multiplied. Subjects will choose the changes in the shapes by pressing a button.

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in the context of fMRI to study blood-oxygenation-level- dependent responses in the brain to sensory stimulation.

Participants will be visually instructed to take a brief deep breath (inhale) and release the breath (exhale). They will inhale and exhale one more time with visual cues at specific times (60 seconds, 120 seconds, 180 seconds, 240 seconds, etc. with successive 60 seconds intervals). A black cross will remain centered on a grey slide during the normal respiration periods. To signal the RC periods, the slide will change color to yellow READY slide, then to green BREATHE IN slide, then to blue BREATHE OUT slide. The sequence will repeat one more time to Breath In and Breath Out and then finally go back to the yellow Breathe Normally slide. The instruction words will be written on the slides. Each slide will be shown for 3 seconds. The task will take a total of 15 minutes (total of 900 seconds with 14 RC periods).

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in the context of fMRI to study blood-oxygenation-level- dependent responses in the brain to sensory stimulation.

High spatial MRI and diffusion tensor imaging (DTI) to assess brain morphology and structural connectivity.

During the MRI scan, subjects will do a task that requires close concentration. Subjects will be asked to respond quickly to images on the computer screen, during which they will hear distracting noises. The subject will be able to remove the distraction in order to complete the task. During some sub-study sessions, subjects will start with no money ($0) and may be able to earn up to $40 if they do not remove the distraction. At other sub-study sessions, subjects will start with $40 and may lose between 25 to $1 each time they remove the distraction. Subjects cannot lose more than $40 in these sessions. Compensation for this sub-study is up to $40 per session, depending on their performance.

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in the context of fMRI to study blood-oxygenation-level- dependent responses in the brain to sensory stimulation.

The Spinner task requires the subject to participate in a game of chance while lying in the MRI scanner. Subjects will be asked to respond by pressing a button. The MID task is a reaction time task. The MID Task tests how quickly a subject can press a button to hit a target on the screen in front of them. If the subject presses the button as soon as the target appears, the subject will score points. Subjects should try to score as many points as you can.

1H MR spectroscopy to assess brain metabolites.

Three fMRI sessions to assess test-retest reliability of functional connectivity (FC) measures at rest and during task performance.

To be used in the context of fMRI to study blood-oxygenation-level- dependent responses in the brain to sensory stimulation.

MRI: we will analyze measures such as the amplitude and the reliability of the test-retest measures of fMRI signals; functional connectivity metrics; tractography between seed and target regions of interest (diffusion tensor imaging, DTI); morphometry of brain regions (using automatic segmentation and voxel-brain morphometry, VBM); and brain metabolite levels in regions of interest (using MR spectroscopy, MRS).

EEG (electroencephalography): we will quantify measures such as event or task-related potentials, and coherence between sensors or sources located close to the brain areas of interest. We are also quantifying blink rates from the electrooculogram (EOG).

Behavioral measures during fMRI tasks: we will quantify measures such as reaction times and accuracy (using MRI compatible response pads) as well as eye movement (using MRI compatible eye trackers) and self-reports of the study experience (i.e. degree of interest and motivation and alertness).

Autonomic data may be collected or observations made during the course of the experiment that will give further information about the state of the body and emotions during experiments (blood pressure, skin conductance, respiratory rate). Self-report data may be collected during the course of the experiment to assess the level of interest, boredom, alertness of the participants.