Back reconstruction step is used to separate individual data-set components from the aggregate set of components calculated from the calculate ICA step. Figure shows the process involved in back reconstruction step.
Calculation involved in back reconstruction step:
Back reconstruction uses information from the data reduction and the ICA steps to reconstruct individual subject spatial maps and time courses. Spatial map is calculated by multiplying weights matrix and product of whitening matrix with the data. Time courses can be calculated by taking the product of dewhitening matrix with the pseudo inverse of weights matrix. These are saved as .mat files with suffixes as '_ica_br*' where * refers to the data-set count.
After the components are reconstructed, the units of spatial maps and time courses are in arbitrary units. The component maps and time courses can be scaled using scaling components step.