Paulus 2000). Previous studies have demonstrated that cerebral excitability was diminished by cathodal stimulation, which hyper• polarizes neurons (Terzuolo and Bullock 1956: Creutzfeldt et al. 1962: Bindmann et al. 1964: Cianside 1968). Bindmann et al. (1964) have shown that cathodal stimulation in ani