Disclosed is a method for imaging brain activity from a set of ultrasound images I(t) of blood in a brain, wherein a measured spectrum s(P,t,ω) is computed at each point P of the ultrasound images, a reference spectrum s(P,ω) is determined at each point P, based on measured spectrums at point P, the reference spectrogram having a high frequency edge decaying in a frequency ωmin(P) to ωmax(P), and a differential intensity is computed as:dI(P,t)=∫ωmin(P)ωmax(P)A(P,ω)[s(P,t,ω)−s(P,ω)]dωwherein A(P,ω) is a positive weighting function.
