Researchers think that a poor ability to localize sound in a complex auditory environment is responsible for the weak speech perception observed under these conditions. Pentobarbital anesthesia prolongs the recovery time of responses to lagging stimulus.
The effects of pentobarbital anesthesia on the precedence effect stem from decreased dissociation of gamma-aminobutyric acid from its receptor (i.e., it is a gamma-aminobutyric acid agonist). Therefore, Yanjun Wang and co-workers from Beijing Chaoyang Hospital, Capital Medical University in China investigated how neurons in the inferior colliculus respond to the paired sounds that produce precedence-effect illusions, and whether their firing behavior can be modulated through inhibition with gamma-aminobutyric acid.
They found that after local gamma-aminobutyric acid application, responses to the lagging stimulus were suppressed. This result, published in the Neural Regeneration Research
(Vol. 9, No. 4, 2014), can provide a new approach for auditory localization and speech understanding of patients with hearing aids under background noise.