Learning and Memory: The Remember-Know Task

1. Participant recruitment

1. Recruit 20 participants.
   1. Participants should be right-handed and have no history of neurological or psychological disorders.
   2. Participants should have normal or corrected-to-normal vision to ensure that they will be able to see the visual cues properly.
   3. Participants should not have metal in their body. This is an important safety requirement due to the high magnetic field involved in fMRI.
   4. Participants should not suffer from claustrophobia, since the fMRI requires lying in the small space of the scanner bore.

2. Pre-scan procedures

1. Fill out pre-scan paperwork.
2. When participants come in for their fMRI scan, instruct them to first fill out a metal screen form to make sure they have no counter-indications for MRI, an incidental-findings form giving consent for their scan to be looked at by a radiologist, and a consent form detailing the risks and benefits of the study.
3. Have the participant sit in front of a laptop computer, and show them 256 color pictures of namable objects (e.g., fan, apple, baseball), each for 3 s.
   1. For each object, the participants press a button to indicate if it was a living or non-living object. This task ensures their attention to the stimuli.
4. Prepare participants to go in the scanner by removing all metal from their body, including belts, wallets, phones, hair clips, coins, and all jewelry.

3. Provide instructions for the participant.

1. In the scanner, show the participant all 256 pictures that were studied before the scan, and an additional 256 novel pictures.
2. Participants judge each picture with "remember", "know", or "novel" responses via an MR-safe button-box.
   1. Instruct participants to respond "remember" if they saw the image during the study session and could recall specific details about its presentation.
   2. Instruct participants to respond "know" if the image was familiar but they did not recall specific details about seeing it before.
   3. Instruct participants to respond "new" if they had not seen the image before.
3. Stress to the participant the importance of keeping their head still throughout the scan.

4. Put the participant in the scanner.

1. Give the participant ear plugs to protect their ears from the noise of the scanner and ear phones to wear so they can hear the experimenter during the scan, and have them lie down on the bed with their head in the coil.
2. Give the participant the emergency squeeze ball and instruct them to squeeze it in case of emergency during the scan.
3. Use foam pads to secure the participants head in the coil to avoid excess movement during the scan, and remind the participant that it is very important to stay as still as possible during the scan, as even the smallest movements blur the images.

5. Data collection

1. Collect high-resolution anatomical scan.
2. Begin functional scanning.
   1. Synchronize the start of stimulus presentation with the start of the scanner.
   2. Present pictures via a laptop connected to a projector. The participant has a mirror above their eyes, reflecting a screen at the back of the scanner bore.
   3. Present each picture for 3 s.
      1. Picture presentation is interspersed with 1.5-4.5 s of a fixation cross baseline, as this is an event-related task. Differential overlap in the hemodynamic response to each trial makes the signals more separable.

6. Post-scan procedures

1. Bring the participant out of the scanner.
2. Debrief the participant.

7. Data analysis

1. Preprocess the data.
   1. Perform motion correction to reduce motion artifacts.
   2. Perform temporal filtering to remove signal drifts.
   3. Smooth the data to increase signal-to-noise ratio.
2. Model the data for each participant.
   1. Create a model of what the expected hemodynamic response should be for each task condition.
   2. Fit the data to this model, resulting in a statistical map, where the value at each voxel represents the extent to which that voxel was involved in the task condition.
   3. Register the participant's brain to a standard atlas in order to combine data across participants.
3. Combine statistical maps across subjects for a group-level analysis of the data.
   1. Threshold the statistical maps, taking into account correction for multiple comparisons. Since statistical tests are performed at every voxel in the brain, we expect a considerable number of false-positive results with standard statistical thresholds. One way to deal with this is to only accept significant voxels if they also occur within a cluster of a given size.