FMRI Ian Cameron
25 important questions on FMRI Ian Cameron
What are the general steps/types of visualization/analysis you can do with your fMRI data?
What questions can you answer with the signal time course?
Was there a difference between conditions?
(Baseline needs to be defined)
What questions can you answer with the signal magnitude in ROI?
- Higher grades + faster learning
- Never study anything twice
- 100% sure, 100% understanding
For my 1st exam I got a C. Then, I started looking for ways to learn better and I came across Study Smart. Since then I have scored a A+, A, A- and another A. I highly recommend it to everyone who wants to hear it. I am so happy with it!!
I was struggling to finish all my first-year subjects for 3 years. Then I discovered Study Smart, which helped me to finish all of them within 3 months.
Because of StudySmart, things are going well in many ways. Before, I always had study stress and no time for anything. Now I feel calm and confident (because of the program). I used to score a B, now I usually score an A or A+.
Hey Chris, I really want to thank you very much for developing the platform, I usually got around C for my exams, now I scored an A+, an A and a A- !!
Since using Study Smart, my average has increased significantly. I even completed a statistics course with a A+ while I'm bad at statistics. I took on extra courses this year, because of Study Smart. Thanks so much!
Ever since I started studying with StudySmart I passed all my exams !!! No more re-sits!! At first, I was happy with a pass and now I only get good grades. Many thanks!
I aced all the courses I studied with Study Smart. For law, I first scored a D, and now an A! I’m 100% sure that I’ll pass all the courses I study with Study Smart.
I always thought I studied well. My grades were fine. I could never have imagined that applying these study skills would have such a huge and direct impact on my grades, my speed and the pleasure I have in learning.
For the first time, I finally feel totally confident about the way I learn. I have the perfect overview and make great progress in terms of speed and the grades I get. Thanks, Chris!
I immediately started to enjoy learning again, and my grades soared. All of a sudden, everything went better. I highly recommend Study Smart to all students..
Being able to create my materials online made the process of studying so much smoother and quicker. I no longer have to spend a huge amount of my time on creating my summaries.
At first, my notes were a mess. Now I use Study Smart to take my notes in a perfectly structured way. It helps me to save a lot of time and do other things I enjoy.
Students that study with Study Smart get better grades. The system applies all the learning methods in such a way that both well-performing students and students who struggle perform much better.
Hi Chris, I would like to thank you very much. Last year I scored C on a course, and this year I got an A+ thanks to your method! Thank you very much!
The largest effect is that my child is more enthusiastic about school! Every parent wants their children to be happy at school, Study Smart made it happen.
In high school, I failed several exams, and that has really changed now. I actually needed this tool very much back then. Since I started studying with StudySmart, I haven't had any D's. My average score is now an A and those are results I would have never had in the past
With my old method, I passed only 3 out of 8 courses. Since I started taking my notes digitally in Study Smart, I have passed all my courses on the first try. For me, StudySmart takes away the stress of wondering if I will pass or not.
Thanks to StudySmart, I passed all my exams, and with better grades than before! On top of that, I have mastered a very good study method now, which I am confident will help me earn my degree.
What is an advantage of analyzing fMRI data as signal magnitudes in ROIs?
It avoids many pitfalls associated with false positives in fMRI.
Give for examples of sample artifacts.
As what will you find your data after the scan on the computer?
What is a DICOM?
A single file that has information about the data (name, image characteristics, properties of scan that created it) and multiple dimensions of image pixel data. For MRI this is gray scale pixel intensity.
What is the spatial and temporal resolution of fMRI data?
Relaitvely high temporally (few seconds for whole brain, less than one sec with more modern sequences).
What are the general steps of/things you have to do as preprocessing?
Must account for subjet movement.
Must account for drift in the signal and any other soures of noise that could affect your statistics.
Have to decide on how to display your data (native subject space?, standard/group averaged spaced?).
Have to decide on how to smooth you data.
Why are the first scans (dummy scans/disdaqs) discarded?
What are two common orders of the preprocessing steps?
FSL) Spatial smoothing -> Statistical analysis -> Spatial normalization
SPM) Spatial normalization -> Spatial smoothing -> Statistical analysis
What is the difference between the two ways to correct for the slice time?
Therefore one either corrects for that at the preprocessing stage (SPM) or at the model stage (FSL). In preprocessing, data is interpolated as if every slice was taken at the same time. Otherwise slices acquired later in TR would appear to have a shofted (earlier) response. In the model approach, the model is shifted rather than changing the data. This requires a more complex model of the signal depending on the slice.
What are the two different descending slice time methods and their disadvantages?
The disadvantage of the sequential approach is that the excitation of one slice may carry over to the next one (slices are not prefectly rectangular). The interleaved approach offers a gap between two neighbouring slices to avoid that problem. However, if the subject moves throughout the scan, a slice may capture another part of the brain than before. That part of the brain will be in a different level of excitation, causing bad data.
How is motion correction in general done?
What are 3 examples of transformation/interpolation methods used for motion correction?
Linear interpolation
Spline
What type of motion can motion correction algorithms correct for and what not?
Head motion which leads to spurious activation
Brain regions of interest which move in position over time
Cannot
Mass motion artifacts (moving large objects that create changes in magnetic field map --> can lead to signals around the edges.
Movement between and within slice acquisition
Non-linear distortions and drop-out due to inhomogeneity of the magnetic field
Interpolation artifacts due to resampling
What is additional motion correction (FSL:ICA AROMA)?
These components can be identified (algorithm or manual) as
-task/signal: lower frequency, blob-like in space and occurs in gray matter
-noise/motion: higher frequency, spikes, ring-like in space and on the edge of brain or in the ventricles
What is normalization and how does it (in general) work?
What is spatial smoothing and what does it do?
This helps to account for spatial variability cross subjects.
What are recommendations for spatial smoothing?
What is temporal filtering used for?
What is global intensity normalization?
Why is MRI data 4 dimensional?
How is MRI data be represented in matrix form?
How is a design matrix structured?
The question on the page originate from the summary of the following study material:
- A unique study and practice tool
- Never study anything twice again
- Get the grades you hope for
- 100% sure, 100% understanding
