brain

What does a wavelet transform plot tell you?

Let’s say you collected some brain data (time series) using NIRS while the participants were performing a task (say finger tapping), and you use the wt function in the “Cross Wavelet and Wavelet Coherence Toolbox” (link dead. Please
Xu Cui
1 min read

Hyperbolic discounting emerges from the scalar property of interval…

Ten dollars today is more attractive than the same amount of money tomorrow and is consistent with the well known proverb, “a bird in the hand is worth two in the bush”. We all know that the value of a reward is discounted over time. How the value di
Xu Cui
16 sec read

Handy programs to visualize NIRS data (5): plot2

Let’s say you have two correlated variables, x and y. You may have more then one data points with x=10 and y=5. But if you do a scatter plot all these data points of the same value will become a single dot. You may want to use circles with size
Xu Cui
31 sec read

Handy programs to visualize NIRS data (4): wt

In case you need to visualize your time series in both time and frequency domain (or just frequency domain), you can use the wt (wavelet transform) function in the Cross Wavelet and Wavelet Coherence toolbox by Grinsted et al. I often find the color
Xu Cui
33 sec read

Handy programs to visualize NIRS data (3): plotFFT

Sometimes you wish to know the spectrum of a time series. plotFFT is a handy function for this purpose. You instantly know the power of the signal at each frequency. Here is an example on how to use this function: figure; plotFFT(randn(1,1000)); Sour
Xu Cui
11 sec read

Handy programs to visualize NIRS data (2): plotTopoMap

Often you need to view the spatial pattern of activation as in the example below. plotTopoMap allows you to do that. It probably only works for Hitachi devices where the spatial relationship between channels are known. In the above example, the activ
Xu Cui
37 sec read

Handy programs to visualize NIRS data (1): plotTraces

You often need to plot the time series of NIRS signal from all channels with event indicators (See the example below). plotTraces can do that easily. In the above example, time series of all 24 channels are plotted. The number on the y-axis indicates
Xu Cui
26 sec read

Converting DICOM files to Analyze file in batch mode

I use SPM’s dicom import function to convert DICOM files to Analyze files. But it’s quite inconvenient if I have 20 subjects. Below is a script to do this conversion automatically. You can call this function inside a loop. function dicom2
Xu Cui
23 sec read

The undiscovered numbers

Arthur and Bert each writes down a positive integer on a piece of paper and then shows it to Charles. Charles then writes two numbers on a blackboard, visible to Arthur and Bert: one of them is the sum of Arthur’s and Bert’s numbers, and
Xu Cui
24 sec read