School of Psychology & Key Laboratory of Adolescent Cyberpsycology and Behavior (CCNU) of Ministry of Education, Central China Normal University, Wuhan, 430079, China; School of Life Sciences & Hubei Key Lab of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, 430079, China.
School of Psychology & Key Laboratory of Adolescent Cyberpsycology and Behavior (CCNU) of Ministry of Education, Central China Normal University, Wuhan, 430079, China.
Hear Res. 2019 Sep 15;381:107777. doi: 10.1016/j.heares.2019.107777. Epub 2019 Aug 6.
The integration of visual and auditory information is important for humans or animals to build an accurate and coherent perception of the external world. Although some evidence has shown some principles of the audiovisual integration, little insight has been gained into its functional purpose. In this study, we investigated the functional influence of dynamic visual input on auditory frequency processing by recording single unit activity in the central nucleus of the inferior colliculus (ICc). Results showed that the auditory responses of ICc neurons to sound frequencies could be enhanced or suppressed by visual stimuli even though the same visual stimuli induced no neural responses when presented alone. For each ICc neuron, the most effective visual stimuli were located in the same azimuth as for auditory stimuli and preceded for ∼20 ms. Additionally, visual stimuli could steepen or flatten the frequency tuning curves (FTCs) of ICc neurons by various visual effects at each responsive frequency. The modulation degree of auditory FTCs was dependent on the minimal thresholds (MTs) of ICc neurons, i.e., with MTs increasing, the modulation degree decreased. Due to the non-homogeneous distribution of MTs which was lowest at 10 kHz, visual modulation of auditory FTCs exhibited a frequency-specific manner, the closer it reached the characteristic frequency (CF) of 10 kHz, the greater modulation. Thus, visual modulation of auditory frequency responses in ICc is dependent not only on the visual stimulus but also on the auditory characteristics of ICc neurons. These results suggest a moment-to-moment visual modulation of auditory frequency responses that in real time increase auditory frequency sensitivity to audiovisual stimuli. Furthermore, in the long term such modulation could serve to instruct auditory adaptive plasticity to maintain necessary and accurate auditory detection and perceptual behavior.
视觉和听觉信息的整合对于人类或动物对外界环境建立准确和连贯的感知非常重要。尽管已有一些证据表明了视听整合的一些原则，但对于其功能目的还知之甚少。在这项研究中，我们通过记录下丘中央核（ICc）中的单个神经元活动，研究了动态视觉输入对听觉频率处理的功能影响。结果表明，即使相同的视觉刺激单独呈现时不会引起神经反应，视觉刺激也可以增强或抑制 ICc 神经元对声音频率的听觉反应。对于每个 ICc 神经元，最有效的视觉刺激位于与听觉刺激相同的方位，并且提前约 20ms。此外，在每个反应频率处，视觉刺激可以通过各种视觉效果使 ICc 神经元的频率调谐曲线（FTCs）变陡或变平。听觉 FTCs 的调制程度取决于 ICc 神经元的最小阈值（MTs），即随着 MTs 的增加，调制程度降低。由于 MTs 在 10kHz 处最低，呈现出非均匀分布，因此视觉对听觉 FTCs 的调制具有频率特异性，越接近特征频率（CF）10kHz，调制越大。因此，ICc 中听觉频率响应的视觉调制不仅取决于视觉刺激，还取决于 ICc 神经元的听觉特征。这些结果表明，视觉对听觉频率响应的调制是实时的，它可以提高对视听刺激的听觉频率敏感性。此外，从长远来看，这种调制可以指导听觉适应性可塑性，以维持必要和准确的听觉检测和感知行为。
