Center for Computational Neuroscience and Neural Technology, Boston University, Boston, MA 02215, United States; Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States.
Clin Neurophysiol. 2014 Sep;125(9):1878-88. doi: 10.1016/j.clinph.2014.01.011. Epub 2014 Jan 29.
Auditory subcortical steady state responses (SSSRs), also known as frequency following responses (FFRs), provide a non-invasive measure of phase-locked neural responses to acoustic and cochlear-induced periodicities. SSSRs have been used both clinically and in basic neurophysiological investigation of auditory function. SSSR data acquisition typically involves thousands of presentations of each stimulus type, sometimes in two polarities, with acquisition times often exceeding an hour per subject. Here, we present a novel approach to reduce the data acquisition times significantly.
Because the sources of the SSSR are deep compared to the primary noise sources, namely background spontaneous cortical activity, the SSSR varies more smoothly over the scalp than the noise. We exploit this property and extract SSSRs efficiently, using multichannel recordings and an eigendecomposition of the complex cross-channel spectral density matrix.
Our proposed method yields SNR improvement exceeding a factor of 3 compared to traditional single-channel methods.
It is possible to reduce data acquisition times for SSSRs significantly with our approach.
The proposed method allows SSSRs to be recorded for several stimulus conditions within a single session and also makes it possible to acquire both SSSRs and cortical EEG responses without increasing the session length.
听觉皮质下稳态反应（SSSRs），也称为频率跟随反应（FFRs），提供了一种对声刺激和耳蜗诱发周期性进行锁相神经反应的非侵入性测量方法。SSSR 已在临床和听觉功能的基础神经生理研究中得到应用。SSSR 数据采集通常涉及到每种刺激类型的数千次呈现，有时是两种极性，每次采集时间通常超过每个受试者 1 小时。在这里，我们提出了一种显著减少数据采集时间的新方法。
由于 SSSR 的源比主要噪声源（即背景自发皮质活动）更深，因此 SSSR 在头皮上的变化比噪声更平滑。我们利用这一特性，使用多通道记录和复通道频谱密度矩阵的特征分解，有效地提取 SSSR。
与传统的单通道方法相比，我们提出的方法可使 SNR 提高超过 3 倍。
我们的方法可以显著减少 SSSR 的数据采集时间。
该方法允许在单个会话中记录多个刺激条件的 SSSR，并且还可以在不增加会话时间的情况下同时记录 SSSR 和皮质 EEG 反应。
