南方医科大学学报

南方医科大学学报 ›› 2021, Vol. 41 ›› Issue (7): 1079-1086.doi: 10.12122/j.issn.1673-4254.2021.07.17

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雌性小鼠次级听皮层对通讯声音的响应识别和修饰加工

雷书君，肖中举
  

  • 出版日期:2021-07-20 发布日期:2021-07-17

Communication sound recognition and response modification in the secondary auditory cortex of female mice

  • Online:2021-07-20 Published:2021-07-17

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摘要： 目的 研究C57雌鼠次级听皮层（A2）对乳鼠叫声（WC）的响应特点及机制。方法 使用在体膜片钳技术和免疫荧光染色标记技术，标记和记录A2声诱发神经元的动作电位发放情况及细胞类型。对照组：使用纯音(Tone)和白噪音（Noise）刺激小鼠。WC声刺激组：使用WC声刺激小鼠，提取WC声中4,5 kHz，9 kHz，13.5 kHz的声波，设置为单一频率模拟组：使用4.5、9、13.5 kHz声波刺激小鼠。双频率模拟组：使用4.5 kHz+9 kHz，9 kHz+13.5 khz，4.5 kHz+13.5 kHz的组合声波刺激雌鼠。三频率模拟组：使用4 kHz+7.7 kHz+13.5 kHz和4.5 kHz 9 kHz+13.5 kHz的组合声波刺激小鼠。最后分析A2单个神经元对WC声以及各组模拟WC声的组合声、Tone、Noise的声诱发动作电位的发放模式、发放数、阈值、延时等情况。结果 通过比较次级听皮层神经元对WC声、各组WC声的模拟声、Tone和Noise的响应发放数，发现在次级听皮层存在3种对WC敏感性不同的神经元，其中，对WC声敏感的神经元，它对WC声的平均响应发放数明显高于对各类模拟声和Noise的平均响应发放数，有统计学差异（P<0.001）；比较这3类神经元对WC声、Tone、Noise的反应延时和阈值，发现对WC敏感的神经元和对WC不敏感的神经元对WC声的平均反应延时长于对纯音的平均反应延时，有统计学差异（P=0.002），但与对Noise的平均反应延时比较，则并无统计学差异（P=0.093）；对WC声敏感的神经元对WC声的响应阈值低于对Tone、Noise的阈值（P=0.02）；通过对神经元动作电位发放模式的分析，发现对WC声敏感的神经元主要是由小白蛋白抑制性中间神经元（PV）组成；免疫荧光双染结果提示实验组中对WC响应的A2神经元中，确实存在抑制性中间神经元。结论 在雌性小鼠A2中，存在对WC通讯声敏感性不同的3种神经元。其中对WC声敏感的神经元主要是PV神经元，它对于不同类型声音的响应特性，有助于解释次级听皮层对通讯声音识别响应和修饰加工的机制。

关键词: 次级听皮层；小白蛋白中间神经元；乳鼠蠕动声；GABA能神经元

Abstract: Objective To study the response characteristics of the secondary auditory cortex (A2) to wriggling calls (WC) and the mechanism of response modulation in female mice. Methods We used patch- clamp and immunofluorescence labeling technique to mark and record the action potential and cell type of A2 neurons. Female C57 mice were stimulated with pure tone and white noise (control), 4.5 kHz, 9 kHz, or 13.5 kHz sound waves extracted from WC (single-frequency simulation group), the combinations of every two of the 3 single- frequency sound waves (two- tone frequency simulation group), or the combinations of 4.5 kHz+7.7 kHz+13.5 kHz and 4.5 kHz+9 kHz+13.5 kHz sound waves (three- frequency simulation group). The firing pattern, firing number, threshold, and latency of the action potential of the A2 neurons were recorded in response to the stimulations. Results By comparison of the spikes elicited by different sound stimulations, we identified 3 types of neurons with different sensitivities to WC. The WC-sensitive neurons had a significantly greater number of spikes in response to WC than to other sounds and noise (P<0.001). Comparison of the latency and threshold revealed significantly longer latencies of the WC-sensitive neurons and WC-insensitive neurons in response to WC stimulation than to pure tone stimulation (P=0.002), but their latencies to WC and noise stimulation were similar (P=0.093). The WC-sensitive neurons also had lower threshold to WC than to pure tone and noise stimulations (P=0.02). Analysis of the firing patterns of action potentials showed that the WC sensitive neurons consisted mainly of parvalbumin interneurons. The results of immunofluorescence labeling indicated that inhibitory interneurons were present in the A2 neurons that responded to WC. Conclusion A2 contains 3 types of neurons with different sensitivities to WC. Among them, the WC- sensitive neurons is mainly PV neurons, whose response characteristics to different types of sounds can help to explain the mechanism of communication sound recognition and response modification in A2.

Key words: secondary auditory cortex; PV inhibitory interneurons; wriggling calls; GABA neurons