Centrotemporal spikes (C-T spikes) (“Rolandic discharges”) in childhood EEGs usually have negative polarity. However, several cases of C-T spikes with positive polarity (positive spikes) were observed. The sample in this study was composed of 144 children whose EEG showed C-T spikes. Ages ranged from 2 to 12 years old. The C-T spikes were observed by referential derivations as well as by linked longitudinal and transverse bipolar derivations. The EEGs of 63 cases (44%) showed C-T spikes on both sides, bilateral dependently or independently. The EEGs of 5 cases (3.5%) showed C-T negative spikes on one side, and C-T positive spikes on the other side. The generator of these potentials is assumed to exist in deep structures of the brain, because these spikes can be observed bilaterally over the head. As the site of such a generator, the hippocampus may be hypothesized, where pyramidal cells are arranged in a form of the letter “C” in the transverse section and the axis of electrical dipoles has different angles. These positive C-T spikes may arise from dipoles oriented horizontally or obliquely to the surface of the brain, and may spread by volume conduction on the scalp.

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