In all electronic devices with the possibility of saving there are tiny magnets that can store your data by the state they are in. In general, there has to be something changed to store information and independent observer should be (theoretically) able to read all the stored information just from one state of brain.
I think keeping some signal in circuit would be really nutrition expensive (through the ion pumps that create the electro-chemical gradients).
So how does a brain store the information?