Dynamics of sinusoidal alpha waves asymmetry in brain electrical field

Abstract

There is no methodical approach suitable for definition of the periodical or non-periodical, stationary or nonstationary curves of brain signals with a help of amplitude, frequency, phase etc. values. It is difficult to determinate the wave shape, i.e. the problem is how to solve the respective pattern recognition. Therefore, we tried to propose a simple method for praxis by help of measurement two main wave time components, interpreting a sinusoidal alpha wave as a triangle, where there is an anterior and a posterior part of wave ascending and descending abscissas in a hope that the sufficient measure are presented by the "legs" only or distances between upper and bottom peak of the wave. All the values of total ascendants are divided by all values of total descendants. For the method validity estimation it was made for this computation separately in two different psychical states-the relaxation and the calculation activity, both with eyes closed. Results are presented as quotient (quotus alpha) which means alpha waves symmetry. If the quotient is equal to 1, or is near to 1, is the alpha wave full or almost symmetrical. When the quotient is lower than 1 the ascendant is shorter than descendent, then alpha wave is asymmetric and has inclination to the left side. In contrary if the quotient is higher than 1 the ascendant is longer than descendent, alpha wave is again asymmetrical, but inclination is oriented to the right side. During mentation is usually quotient lower one and the ascendant is still more lover, alpha waves are sheer, the inclination to the left is more expressive.