基于WICA的事件相關(guān)電位P300少次提取研究
本文選題:事件相關(guān)電位 + WICA ; 參考:《天津師范大學(xué)》2012年碩士論文
【摘要】:事件相關(guān)電位(Event-related Potential, ERP),是與實(shí)際刺激或預(yù)期刺激(聲、光、電等)有固定時(shí)間關(guān)系的腦反應(yīng)所形成的一系列腦電波。有廣泛應(yīng)用的P300是事件相關(guān)電位的重要成分,但其信號(hào)非常微弱,并容易受噪聲干擾,通常提取事件相關(guān)電位要經(jīng)過40~100次的疊加平均,這就需要大量的重復(fù)刺激實(shí)驗(yàn),于是人們力求通過少次疊加的方法來實(shí)現(xiàn)對(duì)事件相關(guān)電位的提取。因此,如何實(shí)現(xiàn)事件相關(guān)電位信號(hào)的少次提取成了腦電信號(hào)處理的重點(diǎn)及難點(diǎn)問題。 由于ERP混疊在自發(fā)腦電之中,而近年發(fā)展起來的獨(dú)立分量分析(Independent Component Analysis, ICA)能夠從多通道的觀測(cè)數(shù)據(jù)中分離出相互獨(dú)立的信號(hào),不受信號(hào)頻譜混疊的限制,適用于腦電信號(hào)中各種噪聲的消除。小波變換(Wavelet Transform)具有時(shí)頻特性并且有分析非平穩(wěn)信號(hào)的優(yōu)勢(shì),在一定程度上能夠精確地分析腦電信號(hào)的瞬態(tài)特性。因此運(yùn)用小波變換與獨(dú)立分量分析相結(jié)合(WICA)的方法,可以對(duì)腦電信號(hào)進(jìn)行高精度子頻帶分析,同時(shí)也可以彌補(bǔ)小波變換算法不能有效解決噪聲和信號(hào)的頻譜混疊的缺陷。 本文將WICA方法應(yīng)用于P300的提取過程中,主要做了以下研究工作: (1)介紹腦電信號(hào)、事件相關(guān)電位以及P300的產(chǎn)生原理、特點(diǎn)、分類以及應(yīng)用等相關(guān)知識(shí)。 (2)深入研究獨(dú)立分量分析和小波變換算法,利用兩種算法結(jié)合即WICA對(duì)腦電信號(hào)進(jìn)行處理。首先,利用db5小波對(duì)腦電信號(hào)進(jìn)行去噪處理,然后把處理過的信號(hào)用ICA算法分解,獲得各個(gè)信號(hào)的獨(dú)立分量,然后根據(jù)事件相關(guān)電位的先驗(yàn)知識(shí)對(duì)各獨(dú)立分量進(jìn)行優(yōu)選,最后重構(gòu)腦電信號(hào)。 (3)利用事件相關(guān)電位的固定鎖時(shí)關(guān)系將處理過的腦電信號(hào)進(jìn)行少次疊加,獲取事件相關(guān)電位信號(hào),并通過P300的先驗(yàn)知識(shí),成功地提取出了P300復(fù)合波中的亞成分。這些亞成分對(duì)人類認(rèn)知等高級(jí)神經(jīng)活動(dòng)有重要意義。 (4)實(shí)驗(yàn)對(duì)比,將WICA方法獲得的P300成分與傳統(tǒng)疊加平均方法獲取的P300成分進(jìn)行對(duì)比,說明本實(shí)驗(yàn)的優(yōu)越性。本實(shí)驗(yàn)對(duì)傳統(tǒng)的基于疊加平均的P300的提取研究提供了新思路,同時(shí)對(duì)基于P300的BCI研究有重要的參考價(jià)值。
[Abstract]:Event - related potential ( ERP ) is a series of brain waves formed by brain reactions with fixed - time relationship with real stimulus or expected stimulus ( acoustic , light , electricity , etc . ) . The widely used event - related potential ( ERP ) is an important component of event - related potential , but its signal is very weak , and it is easy to be disturbed by noise .
Because of ERP aliasing in spontaneous EEG , independent component analysis ( ICA ) developed in recent years can separate independent signals from multi - channel observation data . It is suitable for the elimination of various noises in EEG signals . Wavelet Transform has the advantage of analyzing the transient characteristics of EEG signals .
In this paper , the WICA method is applied to the extraction process , and the following research work is done :
( 1 ) Introduce the relevant knowledge of EEG signal , event - related potential and the generation principle , characteristics , classification and application .
( 2 ) In - depth study of the independent component analysis and wavelet transform algorithm , the EEG signal is processed by combining two algorithms , namely , WICA . First , using db5 wavelet to de - noising the EEG signal , then the processed signal is decomposed by ICA algorithm to obtain the independent component of each signal , and then the independent component is optimized according to the prior knowledge of the event - related potential , and then the EEG signal is reconstructed .
( 3 ) Using the fixed lock - time relation of event - related potential , the processed EEG signal is superimposed on a few times , the event - related potential signal is acquired , and the sub - component in the composite wave of the P 300 is successfully extracted by a priori knowledge of the event , and the sub - components have important significance for the high - grade nerve activity such as human cognition .
( 4 ) Compared with that obtained by the traditional superposition mean method , the experimental results show the superiority of this experiment . This experiment provides a new idea for the traditional extraction study based on the superposition average method , and has important reference value for the study of the BCI study based on P 300 .
【學(xué)位授予單位】:天津師范大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2012
【分類號(hào)】:TN911.7;R33
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