Nonlinear analysis of brain activity in magnetic influenced Parkinson patients

Magnetoencephalogram (MEG) recordings were obtained from the brain of patie nts suffering from Parkinson's disease (PD) using the Superconductive Quant um Interference Device (SQUID). For each patient the magnetic activity was recorded from a total of 64 points of the skull (32 points from each tempor al lobe) as defined by a recording reference system, which is based on the 10-20 Electrode Placement System. Some of the recorded points were observed to exhibit abnormal rhythmic activity, characterized by high amplitudes an d low frequencies. External magnetic stimulation (EMS) with intensity 1-7.5 pT, and frequency the alpha -rhythm of the patient (8-13 Hz) was applied in the left-right temporal, frontal-occipital and vertex (2 minutes over each of the above regions) and the brain magnetic activity was recorded again. The application of the EMS resulted in rapid attenuation of the MEG activit y of PD patients. Furthermore, chaotic dynamic methods were used, in order to estimate the correlation dimension D of the reconstructed phase spaces. The estimated values of D, in conjunction with the results derived from the other data analysis methods, strongly sup port the existence of low dimens ion chaotic structures in the dynamics of cortical activity of PD patients. In addition, the increased values of D of the MEG after the application of EMS when compared with the corresponding ones obtained from the MEGs prior to the EMS, suggest that the neural dynamics are strongly influenced by th e application of EMS.