Principal component analysis of slow brain potentials during six second anticipation intervals.

The comparison of principal component analyses between seven experimental studies demonstrates a remarkable similarity of the extracted components. Slow scalp-recorded potentials of the brain (SPs) during a constant 6 sec foreperiod can be described by an early frontal, and a late preparatory component. Furthermore, an additional intermediate component may be retained by the PCA. This component seems to reduce the between-subject variance and often describes processes dependent on stimulus repetition. There is evidence favoring the varimaxed solution of the PCA for the parametrization of most of the experimental data.