Sign-changing filters similar to cells in primary visual cortex emerge by independent component analysis of temporally convolved natural image sequences

It has been reported that independent component analysis (ICA) of natural image sequences yields spatio-temporal "lters of non-separable spatio-temporal properties. On the contrary, sign changing "lters with separable spatio-temporal properties have not been found via ICA. We show that extending the ICA to temporally convolved inputs develops such receptive "elds (RFs). We argue that temporal convolution may arise from the response function of lagged and non-lagged cells of the LGN. The properties of the emerging RFs as a function of convolution time and the dimension of compression are studied. 2001 Elsevier Science B.V. All rights reserved.