基于触听觉稳态诱发电位的多通道选择性注意机制研究

For those patients who suffer from some sort of amyotrophic lateral sclerosis （ALS） and so lose their voluntary gaze control but with normal tactile and auditory sense, this project aimed to explore the tactile and auditory cross-modal allocation mechanisms of the brain attention resources.When attention was shifted between tactile and auditory modalities or between two different directional tactile channels, the modulation effect for the steady-state evoked potentials (SSEPs) from touch and audition would be studied. This study would focus on how to extract the weak amplitude and phase information of steady-state somatosensory potentials (SSSEPs) and steady-state auditory evoked potentials (SSAEPs) real-timely and accurately, in the presence of noise, by means of Hilbert-Huang transform. The research content mainly includes: 1、Studying the techniques of extraction of SSEPs from two sensory channels of touch and audition, and separation of components of their own “amplitude response" and "phase response”. 2、Studying the cognitive process of attention switching between tactile and auditory modalities or between two different directional tactile channels, to reveal the possible neural mechanisms of modulation effect on SSEPs beacause of different attention task.3、Studying feature extraction algorithm aiming at tactile-auditory synchronous evoked EEG applicable to experimental paradigm of the project, and decoding EEG feature under different mental states of the brain. The expected results of the project not only could expand the tactile-auditory multimodal selective attention mechanisms in cognitive science of brain, but also could lay good foundation for constructing the corresponding brain-computer interface (BCI) system so as to help the patients to establish the channel for interacting with the outside world, and it would have a high value of both science and application.

面向“渐冻人”症患者中眼睛无法凝视但触听觉良好的人群，本项目从挖掘大脑在触听觉通道注意资源分配机制入手，研究注意力在触觉-听觉通道间转移和在触觉通道内空间转移对两大感觉通道稳态诱发电位的调制效应，重点解决如何在噪声背景下，利用希尔伯特-黄变换实时准确地提取微弱的稳态体感和稳态听觉诱发电位的幅度和相位信息。研究内容包括：1、触听觉两大感觉通道稳态诱发电位信号提取，及各自“幅度响应”和“相位响应”成分分离技术；2、触觉通道内空间注意转换和触听觉跨模态注意转换的认知过程，揭示不同注意任务对稳态诱发电位调制效应的可能神经机制；3、适用于本项目实验范式的触听同步诱发脑电信号特征提取算法，对大脑不同思维状态下的脑电表征进行解码。项目预期成果不仅可拓展脑认知科学中触听觉多通道选择性注意机制研究，而且可为将来构建相应的脑-机接口系统从而帮助患者与外界建立交互渠道奠定良好的研究基础，具有科学和应用双重价值。

如何从脑活动数据中发现具有生物学意义的知识及规律，正成为当今神经信息学理论与实践研究的热点与难点。本项目面向“渐冻人”（ALS）症患者中眼睛无法凝视但触听觉良好的人群，以自上而下的内源性选择性注意为研究对象，基于希尔伯特-黄变换联合快速傅里叶变换处理了发生在大脑触听觉通道的初级皮层的感觉信息。通过分析注意力在触觉通道内空间转移和在触觉-听觉通道间转移所诱发的触听觉两大感觉通道稳态诱发电位信号的Fourier频谱特征，成功验证了触觉通道内空间选择性注意调制效应，但是因为本项目自主研发的触觉激励器振动造成的声音干扰缘故，触听觉通道间选择性注意调制效应未能得到成功验证。本项目试图解码多感官注意调制效应的神经机制，属于触听觉多通道注意调制效应在神经工程领域中的初步探索。项目研究成果可拓展现有多通道信息整合与注意之间关系的研究，为将来构建不依赖于外周神经或肌肉组织的基于多模式注意联合分类的独立型脑-机接口系统以服务ALS症患者提供新的对外交流通路，从而帮助他们一定程度上恢复控制外部设备的能力奠定良好的前期研究基础。针对受试接受长时间振动激励后产生疲劳，注意力很难集中的问题，本项目还开展了稳态机械振动激励诱发表面肌电（sEMG）的研究，分析了微力振动激励与sEMG信号的关联性，从而为将来通过微力激励人体体表诱发的被动sEMG信号评价振动疲劳奠定基础。本项目还提出了基于脑电信号评价疲劳状态的方法，并开展了听觉激励对改善疲劳状态的实验研究。通过一定的听觉信号激励方法，激发出被试者平静或兴奋两种不同的情绪状态，从而改善焦虑或疲倦，发现音乐和情绪之间可能存在的关系。将来在BCI技术研究的基础之上，情绪识别可以进一步满足患有特定疾病（ALS症、脑瘫、脑干中风、脊髓损伤等）的患者人群的某些更高级的需求，即通过脑电分析出其对事物的喜好度，比如音乐的选择，从而设计出更加友善和智能的BCI系统。