Li Zijie, Li Jinhong, Wang Shuai, Wang Xuejiao, Chen Jingyu, Qin Ling
Department of Physiology, China Medical University, Shenyang, China.
Front Syst Neurosci. 2021 Mar 19;15:636395. doi: 10.3389/fnsys.2021.636395. eCollection 2021.
Auditory steady-state response (ASSR) is a gamma oscillation evoked by periodic auditory stimuli, which is commonly used in clinical electroencephalographic examination to evaluate the neurological functions. Though it has been suggested that auditory cortex is the origin of ASSR, how the laminar architecture of the neocortex contributes to the ASSR recorded from the brain surface remains unclear.
We used a 16-channel silicon probe to record the local field potential and the single-unit spike activity in the different layers of the auditory cortex of unanesthetized mice. Click-trains with a repetition rate at 40-Hz were present as sound stimuli to evoke ASSR.
We found that the LFPs of all cortical layers showed a stable ASSR synchronizing to the 40-Hz click stimuli, while the ASSR was strongest in the granular (thalamorecipient) layer. Furthermore, time-frequency analyses also revealed the strongest coherence between the signals recorded from the granular layer and pial surface.
Our results reveal that the 40-Hz ASSR primarily shows the evoked gamma oscillation of thalamorecipient layers in the neocortex, and that the ASSR may be a biomarker to detect the cognitive deficits associated with impaired thalamo-cortical connection.
听觉稳态反应（ASSR）是由周期性听觉刺激诱发的γ振荡，常用于临床脑电图检查以评估神经功能。尽管有人认为听觉皮层是ASSR的起源，但新皮层的分层结构如何对从脑表面记录到的ASSR产生影响仍不清楚。
我们使用16通道硅探针记录未麻醉小鼠听觉皮层不同层的局部场电位和单单元锋电位活动。以40赫兹重复率的短声序列作为声音刺激来诱发ASSR。
我们发现所有皮层层的局部场电位均显示出与40赫兹短声刺激同步的稳定ASSR，而在颗粒（丘脑接受）层中ASSR最强。此外，时频分析还揭示了颗粒层和软脑膜表面记录的信号之间具有最强的相干性。
我们的结果表明，40赫兹ASSR主要显示新皮层中丘脑接受层诱发的γ振荡，并且ASSR可能是检测与丘脑-皮层连接受损相关的认知缺陷的生物标志物。
