Evoked Potentials Appearing in the Human Midbrain after Sounding of a Simple Tone

Studies of neuron activity in animals have shown that the brainstem is involved in processing the ends of sounds. We report here an analysis of the reaction of the human midbrain to the ends of sound stimuli. Electrical activity was recorded using a depth electrode located in the cerebral aqueduct. The study was conducted as part of intraoperative monitoring (IOM) with the aim of minimizing neurological deficit in the postoperative period. Results of the analysis of evoked potentials recorded in response to simple tones in six patients are presented. Evoked potentials arising after the start of the sound stimulus showed V S , VI S , S1 S , S2 S , S3 S peaks, associated with nerve impulse conduction along the auditory pathway. The end of the sound stimulus was followed by V E , VI E , S1 E , S2 E , S3 E peaks, which are also associated with the nerve impulse conduction along the auditory pathway, along with the E peak, which most likely reflects the analysis of sound information by midbrain structures.