  The neuromagnetic activity (magnetoencephalogram, MEG) from healthy human
brain and from an epileptic patient against chromatic flickering stimuli has
been earlier analyzed on the basis of a memory functions formalism (MFF).
Information measures of memory as well as relaxation parameters revealed high
individuality and unique features in the neuromagnetic brain responses of each
subject. The current paper demonstrates new capabilities of MFF by studying
cross-correlations between MEG signals obtained from multiple and distant brain
regions. It is shown that the MEG signals of healthy subjects are characterized
by well-defined effects of frequency synchronization and at the same time by
the domination of low-frequency processes. On the contrary, the MEG of a
patient is characterized by a sharp abnormality of frequency synchronization,
and also by prevalence of high-frequency quasi-periodic processes. Modification
of synchronization effects and dynamics of cross-correlations offer a promising
method of detecting pathological abnormalities in brain responses.

Medical Physics;Data Analysis, Statistics and Probability