Practical fMRI AI generated

Question 1

Describe the difference between aligning and coregistering scans in fMRI pre-processing.

Answer 1

Aligning involves correcting the same type of images with translations and rotations for motion correction, while coregistering matches different types of scans.

Question 2

What is the purpose of a visual half field stimulation experiment in fMRI studies?

Answer 2

To activate the visual cortex and test the sensitivity of functional MRI pulse sequences.

Question 3

Define the primary activation location expected in the visual cortex during a visual half field stimulation experiment.

Answer 3

Activation should be found in the contralateral region of the visual cortex.

Question 4

How does the dataset from a visual half field stimulation experiment typically present stimuli to participants?

Answer 4

By showing alternating checkerboard patterns to either the right or left hemifield in a block design.

Question 5

Describe the timeline of left stimulation onsets during a visual half field stimulation experiment.

Answer 5

Every block lasted 20 s (40 s left-right cycle length, 9 cycles, total 6 minutes)

Question 6

What is the purpose of realigning and co-registering scans in fMRI pre-processing?

Answer 6

To correct motion and align different types of scans for accurate spatial processing.

Question 7

How can the movement in fMRI scans impact data quality during analysis?

Answer 7

More movement in scans can lead to worse data quality, affecting the reliability of results.

Question 8

Describe the design of a visual half field stimulation experiment in fMRI.

Answer 8

It involves presenting checkerboard patterns to different hemifields in a block design to activate the visual cortex.

Question 9

Describe the main hypothesis regarding differences in pleasantness in the OFC.

Answer 9

Differences in pleasantness are believed to be represented in the OFC, with liking in the medial OFC and disliking in the lateral OFC.

Question 10

What is the purpose of slice timing correction in fMRI analysis?

Answer 10

Slice timing correction is used to account for timing differences in image acquisition when slices are not acquired simultaneously.

Question 11

Define smoothing in the context of fMRI analysis.

Answer 11

Smoothing in fMRI analysis is done to correct for minor functional or anatomical differences that may still exist between subjects.

Question 12

Explain the concept of normalizing in fMRI analysis.

Answer 12

Normalizing in fMRI involves aligning brain images to a standard space like the MNI space to allow for comparison and analysis across different subjects.

Question 13

What multiple comparison correction was used in the study, and what was the associated T-threshold?

Answer 13

A multiple comparison correction of p<0.05 was used with a T-threshold of 4.83.

Question 14

What is the purpose of using a multiple comparison correction in statistical testing?

Answer 14

Multiple comparison correction is used to reduce the chance of false positives by adjusting the alpha level to account for the increased risk of Type I errors when conducting numerous tests simultaneously.

Question 15

Describe the purpose of the MNI space in brain imaging studies.

Answer 15

The MNI space serves as the reference brain for standardizing and comparing neuroimaging data across different studies and individuals.

Question 16

Define design matrix in the context of neuroimaging studies.

Answer 16

A design matrix in neuroimaging represents the experimental design and includes predictors for each condition or task, as well as nuisance variables like translations and rotations.

Question 17

How can you determine if a person liked or disliked a target stimulus in a neuroimaging study based on contrasts?

Answer 17

Activity differences in the brain after contrasting stimuli can indicate liking or disliking, but the specific preference cannot be determined.

Question 18

Do resting conditions show neural activity in a design matrix for neuroimaging studies?

Answer 18

No, resting conditions do not show neural activity in a design matrix because there is no task-related brain activation during rest.

Question 19

Describe the significance of finding activation in the gustatory cortex during a neuroimaging study.

Answer 19

Activation in the gustatory cortex indicates processing related to taste perception, suggesting involvement in the evaluation of taste stimuli.

Question 20

How do rows and columns in a design matrix relate to scans/images in a neuroimaging study?

Answer 20

Each row in a design matrix typically represents a single scan or image, while columns represent different predictors or variables related to the experimental design.

Question 21

Can you explain the absence of the ‘rest’ condition in a design matrix compared to the experimental timeline in a neuroimaging study?

Answer 21

The ‘rest’ condition does not show up in the design matrix because it lacks neural activity, unlike other task-related conditions that manifest as white lines in the matrix.

Question 22

Do contrasts in neuroimaging studies provide information on specific preferences like liking or disliking stimuli?

Answer 22

Contrasts can show differences in brain activity related to preferences, but they do not directly reveal whether a person liked or disliked a specific stimulus.

Question 23

Describe the activation observed in orbitofrontal cortex.

Answer 23

Activation observed in the orbitofrontal cortex, an important taste/reward area.

Question 24

Do you still find any activation in taste areas after applying FWE-correction with a p-value of 0.05?

Answer 24

Yes, activation is still present, but less visible after correction.

Question 25

Compare the contrasts TARGET vs NEUTRAL and TARGET vs REST. What differences in activation do you notice?

Answer 25

In TARGET vs REST, activation is in the back of the head (vision), while in TARGET vs NEUTRAL, activation is in the front and middle of the head.

Question 26

What do the rows in the design matrix represent?

Answer 26

The rows represent individual participants divided into likers and dislikers.

Question 27

Provide the MNI space coordinates and T-values of the highest peak activation.

Answer 27

T-value: 8.18, MNI coordinates: 42 17 –26, located in the amygdala, associated with emotion and the reward system.

Question 28

Which parametric modulation did you model in the second column of the design matrix? Why is this important?

Answer 28

The second column represents intensity modulation, matching ratings with intensity to ensure perceived and actual intensity match.

Question 29

Can you identify any intensity modulation in taste areas? If so, provide the MNI space coordinates and T-values of the peak voxels.

Answer 29

Intensity modulation present; MNI coordinates and T-values can be provided for peak voxels with anatomical labels.

Question 30

Describe the process of using FWE-correction with a p-value of 0.05 in intensity modulation contrast analysis.

Answer 30

When using FWE-correction with a p-value of 0.05 in intensity modulation contrast analysis, the threshold for activation is set higher to remove any irrelevant activation, thus increasing the stringency of the analysis.

Question 31

Define T-contrast in the context of neuroimaging analysis.

Answer 31

A T-contrast in neuroimaging analysis involves creating a contrast to specifically examine the effect of a particular condition or stimulus, allowing researchers to isolate and study the activation related to that specific factor.

Question 32

How are ‘blobs’ interpreted in the context of contrasts in neuroimaging analysis?

Answer 32

In neuroimaging analysis, ‘blobs’ represent areas of the brain where the difference in activation levels is depicted. In the context of contrasts, they show either higher or lower activation levels compared to the baseline, providing insights into the specific brain regions involved in the analyzed processes.

Question 33

Describe the relationship between taste response and brain activation as mentioned in the content.

Answer 33

The taste response builds up with increasing intensity, peaks when swallowing (with more activation in the motor cortex), and then returns to a resting state or slightly higher when an aftertaste is perceived. Brain activation correlates with the intensity of the taste parameter, with higher intensities leading to increased brain activation.

Question 34

Do higher intensity taste stimuli lead to higher brain activation according to the content?

Answer 34

Yes, according to the content, higher intensity taste stimuli result in higher brain activation, as the brain perceives taste at all intensities and shows slightly higher activation with stronger intensity stimuli.