Nick LaVassar: Difference between revisions

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= Background =
= Introduction =


Color vision deficiency (often called "colorblindness") affects hundreds of millions of people around the world.  The deficiency is sex linked: approximately 8% of men have a CVD versus only  0.5% of females.
Color vision deficiency (often called "colorblindness") affects hundreds of millions of people around the world.  The deficiency is sex linked: approximately 8% of men have a CVD versus only  0.5% of females.  This project aims to simulate the most common types of CVDs for people with normal color perception.


= Methods =
= Background =
== Measuring retinotopic maps ==
Retinotopic maps were obtained in 5 subjects using Population Receptive Field mapping methods [http://white.stanford.edu/~brian/papers/mri/2007-Dumoulin-NI.pdf Dumoulin and Wandell (2008)]. These data were collected for another [http://www.journalofvision.org/9/8/768/ research project] in the Wandell lab. We re-analyzed the data for this project, as described below. 


=== Subjects ===
Color vision deficiencies are characterized by reduced sensitivity to color as a result of anomalies in the eye's color receptors (called cones).  In extremely rare cases, the cones in the eye are either completely absent or totally dysfunctional which results in monochromacy (no color perception).  When only one cone is missing a person is said to be dichromatic.  The most common CVDs are caused by a shift in the sensitivity of one of the types of cone in the eye and is known as anomalous trichromacy.
Subjects were 5 healthy volunteers.


=== MR acquisition ===
CVDs are classified according to which cone type is affected:
Data were obtained on a GE scanner. Et cetera.


=== MR Analysis ===
* Protanomaly - L cone sensitivity is defective.
The MR data was analyzed using [http://white.stanford.edu/newlm/index.php/MrVista mrVista] software tools.  
* Deuteranomaly - M cone sensitivity is defective.
* Tritanomaly - S cone sensitivity is defective.


==== Pre-processing ====
Likewise, someone with dichromatic vision is completely missing either their L, M or S cones, ans is called either a protanope, deuteranope, or tritanope, respectively.
All data were slice-time corrected, motion corrected, and repeated scans were averaged together to create a single average scan for each subject. Et cetera.


==== PRF model fits ====
= Methods =
PRF models were fit with a 2-gaussian model.


==== MNI space ====
== Overview ==
After a pRF model was solved for each subject, the model was trasnformed into MNI template space. This was done by first aligning the high resolution t1-weighted anatomical scan from each subject to an MNI template. Since the pRF model was coregistered to the t1-anatomical scan, the same alignment matrix could then be applied to the pRF model. <br>
Once each pRF model was aligned to MNI space, 4 model parameters - x, y, sigma, and r^2 - were averaged across each of the 6 subjects  in each voxel.


Et cetera.





Revision as of 03:07, 19 March 2011

Introduction

Color vision deficiency (often called "colorblindness") affects hundreds of millions of people around the world. The deficiency is sex linked: approximately 8% of men have a CVD versus only 0.5% of females. This project aims to simulate the most common types of CVDs for people with normal color perception.

Background

Color vision deficiencies are characterized by reduced sensitivity to color as a result of anomalies in the eye's color receptors (called cones). In extremely rare cases, the cones in the eye are either completely absent or totally dysfunctional which results in monochromacy (no color perception). When only one cone is missing a person is said to be dichromatic. The most common CVDs are caused by a shift in the sensitivity of one of the types of cone in the eye and is known as anomalous trichromacy.

CVDs are classified according to which cone type is affected:

  • Protanomaly - L cone sensitivity is defective.
  • Deuteranomaly - M cone sensitivity is defective.
  • Tritanomaly - S cone sensitivity is defective.

Likewise, someone with dichromatic vision is completely missing either their L, M or S cones, ans is called either a protanope, deuteranope, or tritanope, respectively.

Methods

Overview

Results - What you found

Retinotopic models in native space

Some text. Some analysis. Some figures.

Retinotopic models in individual subjects transformed into MNI space

Some text. Some analysis. Some figures.

Retinotopic models in group-averaged data on the MNI template brain

Some text. Some analysis. Some figures. Maybe some equations.


Equations

If you want to use equations, you can use the same formats that are use on wikipedia.
See wikimedia help on formulas for help.
This example of equation use is copied and pasted from wikipedia's article on the DFT.

The sequence of N complex numbers x0, ..., xN−1 is transformed into the sequence of N complex numbers X0, ..., XN−1 by the DFT according to the formula:

where i is the imaginary unit and is a primitive N'th root of unity. (This expression can also be written in terms of a DFT matrix; when scaled appropriately it becomes a unitary matrix and the Xk can thus be viewed as coefficients of x in an orthonormal basis.)

The transform is sometimes denoted by the symbol , as in or or .

The inverse discrete Fourier transform (IDFT) is given by

Retinotopic models in group-averaged data projected back into native space

Some text. Some analysis. Some figures.


Conclusions

Here is where you say what your results mean.

References - Resources and related work

References

Software

Appendix I - Code and Data

Code

File:CodeFile.zip

Data

zip file with my data


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