多模态神经信号协同编码工作记忆的机制研究

发布时间：2018-06-05 16:35

  本文选题：大鼠 + Y迷宫工作记忆　； 参考：《天津医科大学》2014年博士论文

【摘要】：研究目的： 工作记忆(WM)是一类重要的记忆,在许多复杂认知功能中起了重要作用。工作记忆机制的研究是神经科学和认知科学的前沿科学问题。本研究的科学问题为不同模态神经信号如何协同编码工作记忆的机制,包括：(1)局部场电位(local field potentials,LFPs)中与工作记忆相关的主要频率分量,0分量(4-12Hz)和γ分量(30-100Hz)协同编码工作记忆的机制；(2)锋电位(spikes)和局部场电位(LFPs)协同编码工作记忆的机制。 研究方法： (1)工作记忆不同模态神经信号的获取： 本论文中,以SD大鼠在Y迷宫的工作记忆为研究对象,应用在体植入式多通道微电极记录技术,在大鼠内侧前额叶皮层记录神经电活动的时空序列,从中获取LFPs和spikes的时空序列。应用时频从能量分布分析LFPs在WM的主要频段：0、γ,应用带通滤波获取LFPs的θ分量和γ分量。 (2)LFPs的θ和γ频率分量协同编码工作记忆： 采用相位-幅值交叉频率匹配的方法,分别计算定量表征各个通道LFPs中工作记忆相关频段θ、γ分量协同性强度的频率调制指数MI。对4-100Hz的LFPs信号进行带宽为4Hz,移动步长为2Hz的带通滤波,计算定量表征各频带信号之间调制强度的调制指数,绘制相位-幅值频率调制强度分布图。计算0分量、Y分量之间调制强度在工作记忆中的动态变化。(3)LFPs和spikes协同编码工作记忆： 基于联合熵计算spikes与LFPs工作记忆相关分量(θ、γ分量)的联合熵指数(j oint entropy index, JEI),定量表征大鼠工作记忆过程中spikes-LFPs相关分量协同性强度。分别计算工作记忆过程中,动态变化spikes-θ、spikes-低频γ和spikes-高频γ分量JEI值,分析spikes-LFPs协同编码的特征模式。 研究结果： (1)工作记忆过程中LFPs时频分布 在6只大鼠工作记忆过程中,LFPs中低频部分(20Hz)能量高于高频部分能量。在1号到5号大鼠中,θ、γ频带信号的峰值出现在工作记忆参考点前1s内,在6号大鼠中,θ、γ频带信号的峰值出现在工作记忆参考点前1s附近。 (2)LFPs的0-γ对工作记忆的协同编码 1)基于窄带滤波的LFPs不同频率分量调制强度分布 LFPs信号不同频率分量之间调制强度双峰值分别出现在低频信号(4-10Hz)的相位与高频信号幅值(45Hz和80Hz附近)之间。根据调制指数峰值分布情况,将在γ频带进一步划分为低频γ(γL,30-60Hz)和高频γ(γH：60-100Hz)。较高频率信号(20-100Hz)的相位与4-100Hz频率范围内的窄带LFPs信号(带宽：4Hz,移动步长：2Hz)的幅值之间不存在调制作用。 2)LFPs的θγL对工作记忆的协同编码 大鼠前额叶皮层LFPs信号的θ-γL调制指数值在工作记忆过程中动态变化(4只大鼠,共63次实验)。在大鼠行为学正确时,θ-γL之间调制强度在工作记忆过程中显著增加。同时,行为学正确的工作记忆任务中,θ-γL调制强度峰值显著高于行为学错误时两者调制强度。 3)LFPs的θ-γH对工作记忆的协同编码 在行为学正确的实验中,大鼠前额叶皮层LFPs信号θ-γH之间调制指数值在工作记忆过程中无显著变化(4只大鼠,共63次实验)。同时,行为学正确的实验中不同任务时期LFPs θ-γH之间的调制强度与错误实验中相应任务时期调制指数值之间不存在统计学差异。 4)工作记忆过程中,16通道LFPs的θ-γL调制强度动态变化 工作记忆过程中,16通道LFPs的0信号与低频γ信号之间的调制强度变化存在差异性。在大鼠行为学正确的实验中,多数通道中0信号与低频γ信号之间的调制作用强度显著增强,但不是所有通道。 (3)Spikes-LFPs对工作记忆的协同编码 1)Spikes-LFPs的θ分量对工作记忆的协同编码 对工作记忆过程中,6只大鼠各10次实验归一化spikes-LFPs的0分量JEIs值进行平均。结果显示,两者的归一化JEIs值由工作记忆参考点前3s内的0.345±0.038(均值±标准误),增加至工作记忆参考点前1s的最大值0.721±0.033(均值±标准误),两者之间的差异具有统计学意义。对6只大鼠分别进行分析,结果显示,6只大鼠中,工作记忆参考点前1s内spikes-0分量JEIs值均显著升高。 2) Spikes-LFPs的γL分量对工作记忆的协同编码 对工作记忆过程中,6只大鼠各10次实验归一化spikes-γL分量JEIs值进行平均,结果显示,两者的归一化JEIs值由工作记忆参考点前3s内的0.408±0.040(均值±标准误),增加至工作记忆参考点前1s的最大值0.696±0.040(均值±标准误),两者之间的差异具有统计学意义。 3) Spikes-LFPs的γH分量对工作记忆的协同编码 对工作记忆过程中,6只大鼠各10次实验归一化spikes-YH分量JEIs值进行平均,结果显示,两者的归一化JEIs值由工作记忆参考点前3s内的0.393±0.041(均值±标准误),增加至工作记忆参考点前1s的最大值0.690±0.038(均值±标准误),两者之间的差异具有统计学意义。 研究结论 (1)工作记忆过程中,LFPs的θ、γ分量的能量显著增加,为工作记忆主要频率分量。 (2)大鼠前额叶皮层LFPs的θ分量和低频γ分量调制强度在大鼠行为学正确的任务中显著增强,两者协同编码了工作记忆。 (3)大鼠前额叶皮层spikes和LFPs的θ、Y分量协同编码了工作记忆。在大鼠行为学正确的实验中,6只大鼠前额叶皮层spikes和LFPs工作记忆相关分量(0,低频γ和高频γ)的协同性均显著增强并在工作记忆参考点前达到峰值。
[Abstract]:Purpose of study :

Working memory ( WM ) is a kind of important memory , plays an important role in many complex cognitive functions . The research of working memory mechanism is the forward - science problem of neuroscience and cognitive science . The scientific problem of this study is how to co - encode working memory in different modal neural signals , including : ( 1 ) the mechanism of cooperative coding of working memory with the main frequency components , 0 components ( 4 - 12 Hz ) and gamma components ( 30 - 100Hz ) related to working memory in local field potentials ( LFPs ) ;
( 2 ) The mechanism of cooperative coding of working memory with frontal potential and local field potential ( LFPs ) .

Study method :

( 1 ) obtaining the neural signals of different modes of working memory :

In this paper , the spatial - temporal sequence of neural electrical activity was recorded on the medial frontal cortex of rats with the working memory of the Y maze in SD rats . The temporal and temporal sequences of LFPs and LFPs were obtained from the energy distribution analysis LFPs in the main frequency bands of WM : 0 , 纬 , and the 胃 and 纬 components of LFPs were obtained by band - pass filtering .

( 2 ) the theta and gamma frequency components of LFPs cooperatively encode the working memory :

A method for quantitatively characterizing the frequency modulation index MI of working memory related frequency band 胃 and 纬 component coordination intensity in each channel LFPs is calculated by using phase - amplitude cross frequency matching method . The frequency modulation index of the modulation intensity between each frequency band signal is calculated and quantitatively characterized by band - pass filtering with 4 - 100Hz bandwidth of 4Hz and moving step size of 2Hz . The dynamic change of modulation intensity between the 0 and Y components is calculated .

A joint entropy index ( JEI ) of the correlation component ( 胃 , 纬 component ) of the working memory of LFPs was calculated based on the combined entropy .

Results of the study :

( 1 ) Frequency distribution of LFPs in working memory

In the course of working memory of 6 rats , the energy of low frequency part ( 20Hz ) in LFPs was higher than that of high frequency partial energy . In rats 1 to 5 , the peak value of the signal of 胃 and 纬 band appeared within 1 s of the reference point of working memory , and the peak value of the signal of 胃 and 纬 band appeared in the vicinity of the first 1s of working memory reference point .

( 2 ) Co - coding of Working Memory by 0 - 纬 of LFPs

1 ) modulation intensity distribution of different frequency components of LFPs based on narrowband filtering

The two peaks of the modulation intensity between different frequency components of the LFPs signal appear between the phase of the low frequency signal ( 4 - 10 Hz ) and the high frequency signal amplitude ( near 45 Hz and 80 Hz ) , respectively . According to the distribution of the peak distribution of the modulation index , the frequency band is further divided into low frequency . gamma . ( . gamma . L , 30 - 60 Hz ) and high frequency gamma ( . gamma . H : 60 - 100 Hz ) . There is no modulation effect between the phase of the higher frequency signal ( 20 - 100 Hz ) and the amplitude of the narrowband LFPs signal ( bandwidth : 4 Hz , moving step : 2 Hz ) in the 4 - 100 Hz frequency range .

2 ) Coencoding of 胃纬L of LFPs on Working Memory

The value of 胃 - 纬L modulation index of LFPs signal in rat frontal cortex was dynamically changed during working memory ( 4 rats , 63 experiments ) . In the correct behavior of rats , the modulation intensity between 胃 - 纬L increased significantly in the course of working memory . At the same time , in the correct working memory task , 胃 - 纬L modulation intensity peak was significantly higher than that of behavioral error .

3 ) The Synergistic Coding of 胃 - 纬H of LFPs on Working Memory

In the correct behavior experiment , there was no significant change in the modulation index between LFPs signal 胃 - 纬H in the frontal cortex of rats ( 4 rats , 63 experiments ) . At the same time , there is no statistical difference between the modulation intensity between LFPs 胃 - 纬H and the modulation index value in the wrong experiment .

4 ) Dynamic change of 胃 - 纬L modulation intensity of 16 - channel LFPs during working memory

In the course of working memory , there is a difference in modulation intensity between 0 - signal and low - frequency 纬 - signal in 16 - channel LFPs . In the correct experiment of rat behavior , the intensity of modulation between 0 - signal and low - frequency 纬 - signal in most channels is significantly enhanced , but not all channels .

( 3 ) Co - coding of Spikes - LFPs on Working Memory

1 ) Synergistic coding of theta component of Spikes - LFPs on working memory

The results showed that the normalized JEIs value was 0.345 卤 0.038 ( mean 卤 standard error ) within 3 seconds before the reference point of working memory and 0.721 卤 0.033 ( mean 卤 standard error ) in the first 1s of the reference point of working memory , and the difference between them was statistically significant .

2 ) Co - coding of the 纬L component of Spikes - LFPs on working memory

In the course of working memory , the values of JEIs were averaged for 10 experiments in 6 rats . The results showed that the normalized JEIs value was 0.408 卤 0.040 ( mean 卤 standard error ) within 3s of the reference point of working memory , and the maximum value of 1s in the reference point of working memory was 0.696 卤 0.040 ( mean 卤 standard error ) , and the difference between them was statistically significant .

3 ) Co - coding of the 纬H component of Spikes - LFPs on working memory

The results showed that the normalized JEIs values were 0.393 卤 0.041 ( mean 卤 standard error ) within 3s of the reference point of working memory and 0.690 卤 0.038 ( mean 卤 standard error ) of 1s before the reference point of working memory , and the difference between them was statistically significant .

Conclusions of the study

( 1 ) In the process of working memory , the energy of LFPs is significantly increased , which is the main frequency component of working memory .

( 2 ) The theta and low frequency gamma - component modulation intensity of LFPs in rat frontal cortex were significantly enhanced in the correct task of behavioral learning in rats . Both of them co - encoded the working memory .

( 3 ) The theta and Y components of the frontal lobe cortex and LFPs of the rats co - encoded the working memory . In the correct experiment of rat behavior , the synergistic activity of the related components ( 0 , low frequency gamma and high frequency gamma ) of 6 rats in the frontal cortex and LFPs was significantly enhanced and reached the peak before the reference point of the working memory .
【学位授予单位】：天津医科大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：R318.04

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