Let me elaborate on Jolly's answer. Say you you have this progression:

||Gminor7 || Aminor7 ||Bbmajor7 ||Aminor7 ||

Now, this is in Gminor, but because of the Aminor7, the parent scale is Fmajor, meaning that you would want to be soloing in G dorian (which is the second mode of the Fmajor scale)