A comparative study of a theoretical neural net model with MEG data from epileptic patients and normal individuals

Abstract

Objective: The aim of this study was to compare a theoretical neural net model with MEG data from epileptic patients and normal individuals.

Methods: Our experimental study population included 10 epilepsy sufferers and 10 healthy subjects. The recordings were obtained with a one-channel biomagnetometer SQUID in a magnetically shielded room.

Results: Using the method of x2-fitting it was found that the MEG amplitudes in epileptic patients and normal subjects had Poisson and Gauss distributions respectively. The Poisson connectivity derived from the theoretical neural model represents the state of epilepsy, whereas the Gauss connectivity represents normal behavior. The MEG data obtained from epileptic areas had higher amplitudes than the MEG from normal regions and were comparable with the theoretical magnetic fields from Poisson and Gauss distributions. Furthermore, the magnetic field derived from the theoretical model had amplitudes in the same order as the recorded MEG from the 20 participants.

Conclusion: The approximation of the theoretical neural net model with real MEG data provides information about the structure of the brain function in epileptic and normal states encouraging further studies to be conducted.

Figure 1

The MEG recorded from an epileptic patient over an interval of 1 s duration. The x-axis represents the time sequence and the y-axis the magnetic field.

Figure 2

The MEG recorded from a healthy subject over an interval of 1 s duration. The x-axis represents the time sequence and the y-axis the magnetic field.

Figure 3

The magnetic field derived from the theoretical model with Poisson distribution. The x-axis represents the time sequence and the y-axis the magnetic field. Parameters: m_a = 0.6, θ_a = 5, = 15, h_a = 0; m_b = 0.2, θ_b = 4, = 192, h_b = 0.01; m_c = 0.1, θ_c = 3, = 34, h_c = 0.01; m_d = 0.1, θ_d = 3, = 32, h_d = 0; K^± = 1.

Figure 4

The magnetic field derived from the theoretical model with Gauss distribution. The x-axis represents the time sequence and the y-axis the magnetic field. Parameters: m_a = 0.7, θ_a = 6, = 14, h_a = 0; m_b = 0.08, θ_b = 4, = 240, h_b = 0.02; m_c = 0.02, θ_c = 4, = 400, h_c = 0.0; m_d = 0.1, θ_d = 4, = 337, h_d = 0; m_e = 0.1, θ_e = 4, = 294, h_e = 0.03; K^± = 1.