Effects of electrical stimulation in vestibular cortex areas in humans.

The case of a patient with focal epilepsy is reported who underwent presurgical evaluation by stereotactic intracranial electroencephalographic (EEG) recording. A subdural semi-grid electrode, consisting of three multi-channel strip electrodes, was implanted over the temporal lobe and temporo-occipital region; one multi-channel depth electrode was applied towards the posterior insular cortex. During electrical stimulation and EEG monitoring eye movements were recorded by 3-D video-oculography. Stimulation of the medial temporal gyrus induced blurring of vision and horizontal nystagmus. Stimulation of the superior temporal gyrus with low intensities also induced blurring of vision and a similar nystagmus, whereas increased stimulus intensity elicited a nystagmus with horizontal, vertical, and torsional components. These findings support the hypothesis that the superior temporal gyrus is one of the regions of a multisensory network that plays a crucial role in the processing of vestibulo-ocular information.