Planar curve analysis of three-channel auditory brain stem response: a preliminary report

Recording of auditory brain stem responses (ABRs) were made in guinea pigs by means of far-field computer averaging from three orthogonal electrode pairs. The 'Y' locations were mouth and nuchal ridge, 'X' locations left and right mastoids, and 'Z' locations vertex and throat. Three-dimensional models were constructed to plot simultaneous points from the three averages in a voltage-voltage-voltage space. In all five animals tested, at least three subsets of sequential data points lie in separate planes. The data points in each plane roughly correspond to waves I to III in the guinea pig ABR as recorded from the vertex-throat electrode pair. The planarity of data points is a new observation and is not predicted from the single-channel recordings. Three-dimensional planes are also found by means of vectorcardiography, which suggests some underlying principle, such as synchrony and homogeneity of anatomical position of the generators. Planar analysis of ABRs may be useful in analyzing and utilizing the additional information obtainable from 'non-standard' electrode pairs.