Brainstem frequency-following response recorded from one vertical and three horizontal electrode derivations.

The human brainstem frequency-following response reflects neural activity to periodic auditory stimuli. Responses were simultaneously recorded from one vertically oriented and three horizontally oriented electrode derivations. Nine participants each received a total Of 16,000 tone repetitions, 4,000 for each of four stimulus frequencies: 222, 266, 350, and 450 Hz. The responses were digitally filtered, quantified by correlation and spectral analysis, and statistically evaluated by repeated measure analysis of variance. While the various horizontal derivation responses did not differ from each other in latency (values tightly clustered around M = 2.60 msec.), the: vertical derivation response occurred significantly later (M = 4.38 msec.). The smaller latency for the horizontal responses suggests an origin within the acoustic nerve, while the larger latency for the Vertical response suggests a central brainstem origin The largest response amplitude resulted from gold "tiptrode" electrodes placed in each auditory meatus, suggesting that this electrode derivation provided the most accurate (noninvasive) assessment of short-latency events originating at the level of the auditory nerve.