A computerised EEG-analyzing system for small laboratory animals

The experimental setup, including instrumentation and software packaging, is described for the use of a minicomputer as an on-line analyzing system of the EEG in rats. Complete fast Fourier transformation of the EEG sampled in 15 episodes of 10 s each is plotted out within 7 min after the start of registration of the EEG signal. The influence of high voltage spikes, spindles and baseline drift on the power density spectrum is shown and a method of clipping is presented that excludes these kinds of artefacts. The normalized standard error of the power density estimate is determined by the smoothing procedure and is at maximum 26%.