Investigation of the temporal and spectral characteristics of certain artifact signals and background bioelectric activity

Conclusions

1. The As of extrabrain origin caused by “winking,” “eye movement,” and “swallowing” are manifested significantly in the frequency range Δf=0.5−20 Hz at various points of the surface of a person's head and in the overwhelming majority of cases exceed the BBA level severalfold. In this case the times of occurrence of the AS at various points of the head surface differ insignificantly, and the form of the AS has a qualitatively identical character.

2. The AS caused by “winking” and “eye movements” consist of positive and negative components. The average duration of these components$\tilde \tau _{{\text{CO}}}$=0.46 sec with standard deviation σ_τ=0.084 sec.

3. The AS caused by “swallowing” in the frequency range 0.5–20 Hz has a “two-humped” character and an average duration$\tilde \tau _{{\text{AS}}}$=1.62 sec with σ_τ=0.27 sec. In the frequency range 20–500 Hz the corresponding AS are manifested by an increase of general bioelectricactivity, in which case τ_AS=1.65 sec, σ_τ=0.2 sec.

The data obtained on the form of the AS and their duration make it possible to develop the structure of a quasi-optimal channel of their detection, in particular, with the use of postdetector optimization with respect to the duration of the AS. Such noise-immune channels can be realized for detecting each of the types of AS and the given set of AS. In this case worsening of the noise immunity of the channel detecting several types of AS compared with the corresponding ones for each of the types may prove to be negligible.