Electroencephalographic cortical oscillations and saccadic eye movements in humans

A model predicting different types of saccades has suggested that the presence of rhythmic brain activity determines whether a subject will produce regular or express saccades. We studied cortical oscillations preceding saccadic eye movements. Brain electrical activity was recorded in nine healthy adults continuously from 30 electrodes while subjects performed saccades. In a so-called gap condition multimodal latency distributions resulted. Express saccades were preceded by different oscillatory activity than regular saccades. This was a highly significant finding restricted to the alpha and beta bands of the EEG. Step-wise discriminant analysis showed that cortical oscillations measured from only few electrode sites allowed to predict reliably which type of saccade a subject will make. These findings support the notion that stimulus-induced oscillations of the human EEG may modulate thresholds for triggering saccades.