Cortical representation of the vestibular system as evidenced by brain electrical activity mapping of vestibular late evoked potentials.

We examined the space and temporal distributions of the rotatory evoked brain electrical activity patterns (brain electrical activity mapping of vestibular evoked potentials [VestEP]) in humans. We performed a longitudinal scalp line analysis, transversal line analysis, and clockwise/counterclockwise rotation analysis of the VestEP principal components in 75 healthy persons aged 22 to 30 years (mean: 25.8). We found that the shortest VestEP latencies and the highest amplitudes were registered in a relatively distinct cortical area that is covered by the transversal electrode line T3-C3-Cz-C4-T4, in accordance with the 10/20 international electrode scheme. This area corresponds to the posterior part of the frontal lobe (Brodmann's area 4, the primary motor field of the isocortex) and the anterior parts of the cerebral parietal lobe (the gyrus postcentralis, which corresponds to the primary somatosensory fields, Brodmann's areas 1, 2, and 3). In this article, we discuss a method of investigation that exhibits the VestEPs, and we review one normal case and three typical cases of pathologic VestEPs.