Inversed current source density (iCSD) method
The current source density (CSD) method is used for converting measured electrical potentials in the brain to their origin: the transmembrane currents. The potential is usually measured at different cortical depths with a straight electrode with several (around 20) measuring contacts. The inter-contact distance (spatial resolution) is usually about 0.1 mm.
In  we have developed new methods for estimating the CSD based on inversion of the forward electrostatic solution. The methods are called the inversed CSD (iCSD) methods, and their pros compared to the standard CSD methods are:
- the CSD can be computed correctly for spatial confined CSD activity
- the inter-contact distance does not have to be constant, thus even experiments where one electrode contact is damaged can be used to compute the CSD
- the methods could produce continuous CSD functions as output, allowing one to use continuous filters (e.g. gaussian) in case of spatial noise
- the methods could compute CSD in with different conductivity in cortex than above (to prevent cortex from drying out during the experiment oil or saline are normally put on top of cortex)
- the methods compute CSD for all contact position
A MATLAB toolbox for estimating CSD is developed. This uses a graphical user interface, is simple to use, and estimates the CSD based on the iCSD methods as well as the standard CSD method. Please have a look at the User guide (pdf) for more information.
Download the MATLAB toolbox here: CSDplotter-0.1.1.zip
- K. Pettersen, A. Devor, I. Ulbert, A.M. Dale and G.T. Einevoll,
Current-source density estimation based on inversion of electrostatic forward solution:
Effects of finite extent of neuronal activity and conductivity discontinuities,
Journal of Neuroscience Methods (2006).