Using ICA on 3rd order cumulant

I was reading the article $textit{Application of Higher Order Statistics for Atrial Arrhythmia Classification}$, and they mentioned using the third order cumulant $C_3^x = m_3^x(i,j) = E[x(n)x(n+i)x(n+j)]$

and applying independent component analysis on it. The article says,

"In the present study, the performances of two methods are compared: (i) 3rd order HOS cumulants and (ii) HOS bispectrum. The 3rd order cumulant and bispectrum coefficients are subjected to dimensionality reduction using independent component analysis (ICA) and classified using classification and regression tree.."

Can you please explain to me the specifics of how to apply ICA on the 3rd order cumulant to reduce the dimensions. You may assume that $x(n)$
is the heart beat signal and that we only consider the third order cumulant on the domain $(i,j) in [-2, 2]times[-2, 2]$