Suppression of the Cognitive Auditory Evoked Potential P300 in School-Age Children with Normal Hearing
Introduction: Auditory processing depends on afferent and efferent auditory pathways integrity. Most of the studies designed to investigate the efferent system focused on the suppression of the otoacoustic emissions. However, the neural mechanisms underlying efferent activity on higher regions, such as thalamus and cortex, are still not well known.
Objectives: To analyze the suppression effect of the cognitive auditory evoked potential in children with normal hearing.
Methods: Eighteen children aged 8 to 13 years participated in the study. All the participants had pure-tone threshold below 20 dBHL for octaves from 250 to 8,000 Hz, “A”-type tympanogram with the presence of ipsilateral and contralateral acoustic reflexes, functional integrity of auditory pathways assessed by ABR, and no neurological disorders. P300 was recorded at 70 dBHL. The stimulus presented was tone burst at the frequency of 2 kHz for the infrequent stimulus and 1 kHz for the frequent one. The equipment used was a Biologic Navigator Pro and the test was repeated using contralateral white noise stimulus of 70 dBHL.
Results: The studied children showed significantly longer P300 latencies at the presence of white noise contralateral stimulation. Amplitude mean values reduced with white noise, but there was no statistical significance.
Conclusion: These results suggest a possible influence of the auditory efferent system over the P300 responses when contralateral white noise stimulation is used, causing longer wave latencies. New studies should be conducted for a better understanding of these results and for improving the use of this procedure in clinical researches.
Keywords: hearing, auditory evoked potentials, electrophysiology.