params = {'n_sources': 30}?

[g874259]

Dear,

I would like to know what the following parameter mean here.
params = {'n_sources': 30}

Because I would like to find a way to fix the number of output points after CSD caculation, e.g. from 9 electrodes I have 100 points after CSD calculation. But, I would like to have 9 points after CSD calculation.

Thank you,

JJ

[danek8317]

Hi,

Let me explain how kCSD works: you assume a distribution of sources in space in a form of linear combination of individual basis sources. Say, overlapping Gaussians. In the case you mention, their number is 30. The estimation of the sources is done from the potentials you measured and is done in the whole space. You have to evaluate its value in every points you are interested in. By default, it is a set of 100 points. If you need 9, you can just take 9 our of 100. Or, you can just request the 9 you need.

In 1D, gdX is the distance between the consecutive estimation points, controls their number being nx. See line 106 in
https://github.com/INCF/pykCSD/blob/master/pykCSD/KCSD1D.py
Conceptually it is possible to specify any points you need and compute the estimation there but this has not been implemented in the present code. In other dimensions you will find similar constructs.

Question: why would you like to see just the 9 (presumably, at the electrode locations)? The CSD is distributed all over the place.

Notes

1. For the theory check these papers:
   http://www.neuroinf.pl/Members/danek/homepage/preprints/Article.2010-10-12.1044/getFile
   http://www.neuroinf.pl/Members/danek/homepage/preprints/Article.2013-12-16.4021/getFile
   (for citations see here http://www.neuroinf.pl/Members/danek/homepage/publications.html).
2. You may consult also the matlab version of the 1D and 2D code for comparison
   http://software.incf.org/software/kcsd

Daniel