An Experimental Study Of Acoustically Evoked Short Latency Negative Responses(ASNR) In Guinea Pigs

Objectives To research whether there is a difference between the normal and deafened ears of the ASNR's indicators,which contain the threshold,latency and appearance rate.Stereotaxic coordinate guided electrolytic lesion was applied on animals brainstem nuclei,the vestibular nuclei,to define the neural origin of ASNR.Methods Forty healthy guinea pigs were employed in the experiment,which were randomly divided into the control group(8 subjects,16ears),the masking group(16 subjects,32 ears)and the deafened group(16 subjects,32 ears).Both the masking group and the deafened group were further divided into ASNR group and non-ASNR group based on the presence of ASNR.Electrolytic lesion was conducted to the vestibular nuclei,followed by ABR/ASNR recording.The indicators were analyzed in different groups before and after the lesion.The lesioned structures were verified by brainstem slice and light microscope.Results The present study evoked ASNR was 24 ears(75.0%,24/32)in masking group and 12 ears(46.2%,12/26)in deafened group.The ASNR was eliminated due to the electrolytic destruction to the vestibular nuclei.There was no significance of the threshold and latency between the masking ASNR group and the deafened ASNR group(p>0.05).Brainstem slice defined the damage part accurately.Conclusions This pilot study shows that acoustically evoked short latency negative response(ASNR)is successfully elicited in normal and deafened guinea pigs.White noise(WN)masking is a kind of scientific method,which can be used to imitate profound loss hearing ears and make ASNR animal model.This provides theory and experiment basis for the subsequent experiments.Based on the fact that ABR is a complex of ABR and a vestibular potential of ASNR,it is not pure enough to evaluate auditory pathway and need to be modified by ABR-ASNR="Pure"ABR.In addition,ASNR is closely tied with vestibular nucleus.