value at each pixel preferably the mr images continue to be acquired sequentially after the activation task and or the stimulus is stopped care is taken to maintain image registration alignment so that all the intensity values of a pixel in a series of images pertain to the same location a response vector is constructed from a time series of intensity values of a single pixel of the sequential mr images each intensity value of a single series represents a coordinate of a vector in an n dimension space where n is the number of images thus all the intensity values of a pixel from a series of images define a response vector in this space from a plurality of such response vectors each one corresponding to one of the selected pixels a filtered response vector is obtained by one of the methods described above the logic of some preferred embodiments hereof as schematically shown in fig2 consists in separating the total fmri signals 100 relative to an area of interest or all the imaged pixels space into at least two subspaces namely u201c signal u201d and u201c noise u201d subspaces by using eigenanalysis 102 an orthonormal basis of vectors which span the u201c signal u201d subspace is then constructed 106 by a non linear filtering method for example singular value decomposition 104 gram schmidt 104 u2032 and other s 104 u2033 the basis vector s thus obtained is are used as detection function s to synchronously detect the pixel response function s from the.