The epileptic nature of rodent electrocortical polyspiking is still unproven

Electrocortical polyspiking has been reported in guinea pigs, tottering mice, and several strains of laboratory rats. Some investigators have interpreted the polyspiking activity (PSA) to be epileptic in nature, specifically analogous to human petit mal spike-wave discharges; others have assumed PSA to be the rodent equivalent of human mu and feline sensorimotor rhythms. This article provides additional data on PSA in rats, consistent with previous reports that it is associated with behavioral immobility, occurs spontaneously, is bilaterally symmetrical, has a frequency of about 7 to 9/s, and is associated with vibrissa tremor. The PSA frequency varied in relation to the difference between fast and slow vibrissa tremor, as reported previously. A review of these data and the nine earlier publications on PSA reveals that the epileptic nature of PSA is still unproven, and there is strong support for the proposal that it is a normal EEG pattern.