Three example independent source components. Time series (first column), spectrum (second column), filter (third column) and pattern (fourth column) of three components. The first row (a) shows an alpha generator in the occipital lobe. The second row (b) shows a rare muscle artifact component with an increased spectrum in higher frequencies. The third line (c) shows an eye artifact component that appears regularly, has an increases spectrum in lower frequencies and a typical front-back distribution in the pattern.