Fieldtrip Source Reconstruction Notes

Notes for the tutorial: Source reconstruction using beamforming techniques

Source reconstruction methods:

1. Single and multiple (point like) dipole models
   • Assume a small number of sources
   • Where (& how many) are strongest source
2. Distributed dipole models
   • Assume activity everywhere
   • What is the distribution of activity over the brain
3. Spatial filtering
   • Assume that the time-courses of different sources are uncorrelated
   • What is the amount of activity at a given brain location

Use multitapers to smooth the frequency spectrum, and get the targeted time window and the frequency range. Multitapering - increase frequency smoothing without changing length time window.

The beamformer (LCMV & DICS) are source localization methods for time domain signals and frequency domain signals using spatial filtering. This method estimate the source activity on every point of a grid, find a matrix that maximize the variance of the target source point and minimize that for the others. (Will need to follow up with the original papers for LCMV and DICS).