声-电联合刺激对人工耳蜗使用者竞争语境言语识别的去信息掩蔽作用及相关神经生理机制研究

人工耳蜗（CI）使用者竞争语境言语识别困难，核心在于听皮层去信息掩蔽（IM）能力减弱，但其机制不清。双模式声电联合刺激可不同程度改善CI使用者表现，但其对听皮层去IM的影响及声电刺激相互作用不明。我们前期发现IM与掩蔽声特征相关，去IM的双耳整合效应个体差异大且与听皮层发育相关。故我们假设IM可能存在亚成分，声电刺激去IM作用与亚成分相关，声电信号在听皮层或存在相互竞争。我们拟应用前期研发的测试语料系统评估CI使用者竞争语境下的言语识别表现，独立量化IM亚成分，同时应用神经功能影像及脑电时空分析评估去IM时的听皮层激活模式。对比分析行为学与神经生理学表现，从而明确IM发生机制、声电刺激去IM作用及二者相互关系。最后我们试图通过经颅磁刺激影响CI候选者听觉中枢神经元兴奋性，探究无创脑干预对耳聋患者听皮层可塑性及CI术后去IM作用的影响，这为提高CI使用者的困难言语感知奠定了实验基础及理论依据。

Cochlear implant (CI) users do not experience release from masking with competing speakers, a finding that is attributed to informational masking (IM). Poor ability to get release from IM mostly due to the cortical cross-modal reorgnization and/or intra-modal plasticity caused by hearing deprivation. It is showed that acoustic combined with electric stimulation could somewhat improve CI users speech perception performance with competing speech masker. However, it is unclear how the acoustic/electric stimulation contribute to the release from IM, and if there is an interaction. We have found that IM tends to vary due to a wide range of masker features, and correlates with the development of auditory cortex. Moreover, binaural redundancy may interfere with perception of competing speech, and there is a large variation among normal-hearing children and adults. As such, we hypothesized that the IM may have independent components which can evaluated separately. The contribution of acoustic-electric stimulation my depend on the components. These two different stimulation (acoustic and electric) may interfere with each other in auditory cortex regarding to the effect on IM. We are going to evaluated CI users with contralateral hearing aid and normal-hearing (NH) children sentence recognition as a function of the masker features between the target and masker streams in order to study the IM components. Meanwhile, we are going to study the auditory cortical activity during the speech perception mission by using multi-channel electroencephalography (EEG) and positron emission tomography (PET). By comparing the speech perception performance and neurophysiologic evidence, we try to figure out the the components of IM, the contribution of acoustic-electric stimulation to release from IM, and their interaction in auditory cortex. At last, we are going to study the effect of repeated transcranial magnetic stimulation on the auditory cortical plasticity, which may affect the CI users’ ability getting release from IM. In this study, we aim to figure out the neurophysiologic mechanism of IM, and the effect of acoustic-electric stimulation on release from IM. This work is significantly meaningful for CI users’ speech perception improvement with competing speech.