触觉—触觉单—模式和听觉—触觉交叉模式工作记忆的神经机制的研究

目的:探讨听觉-触觉交叉模式工作记忆的大脑神经活动机理。方法:训练12个正常受试者学习触觉-触觉单一模式和听觉-触觉交叉模式工作记忆任务后,利用Neuroscan EEG系统记录脑电活动,对脑电数据分析,着重考察延时过程中事件相关脑电成分(ERP)在触觉单一模式和交叉模式中的异同。我们以往交叉模式的研究表明:在工作记忆延时过程中存在着2个主要的脑电成分LPC(Late Positive Component)和LNC(Late Negative Component)。本研究中加入了新的感觉模式——听觉,并通过比较单一模式和交叉模式,以及交叉模式中匹配和不需匹配任务间脑电成分的差异,进一步证明了交叉模式工作记忆中相继的LPC和LNC所提示的神经认知功能:不同感觉模式间的信息交互,工作记忆的维持和执行。     

振动触觉频率信息的工作记忆容量及存储机制

工作记忆可以同时保存多个信息并且容量有限, 这一内在机制是工作记忆研究的重点问题。视觉和言语等研究领域都发现工作记忆能够存储多个信息单元, 但对振动触觉工作记忆是否能存储多个频率信息目前尚无相关研究。由于振动触觉频率刺激和视觉刺激具有不同的神经编码机制, 以及振动频率信息是通过躯体感觉产生的模拟的、单维的、参数化信息, 振动触觉工作记忆容量及其加工存储机制的研究也必不可少。首先, 本项目将采用新的实验范式, 探究不同的刺激呈现方式以及不同反应报告方式下, 振动触觉工作记忆的容量及其认知机制。其次, 本项目也将同时运用功能磁共振成像(fMRI)技术, 来阐述振动触觉工作记忆加工存储的神经机制。探究基于触觉频率信息的参数工作记忆容量及其神经机制是完善工作记忆模型的重要补充, 将有助于提高我们对工作记忆系统的理解, 并为视觉、听觉、触觉多模态感知觉信息的跨通道研究奠定基础。     

工作记忆的神经振荡调控：基于神经振荡夹带现象

工作记忆的神经振荡机制研究是当前记忆领域的研究热点之一。那么, 神经振荡仅仅是工作记忆过程的伴随现象, 还是直接参与并调控了工作记忆的加工过程?已有研究发现, 大脑内部的神经振荡活动在外界节律性刺激的驱动下, 逐步与外界刺激节律相位同步化, 这一现象被称为“神经振荡夹带”。重复经颅磁刺激(repetitive Transcranial Magnetic Stimulation, rTMS)和经颅交流电刺激(transcranial Alternating Current Stimulation, tACS)干预研究基于此现象, 对大脑局部脑区施加节律性磁、电刺激, 进而调控工作记忆过程中特定频段的神经振荡活动、跨频段的神经振荡耦合或跨脑区的神经振荡相位同步, 为神经振荡参与工作记忆加工提供较为直接的因果证据。未来研究需考虑从脑网络的角度出发, 调控多个脑区之间的神经振荡活动, 进一步考察神经振荡对工作记忆的影响。此外, 还需注意探索和优化rTMS/tACS调控工作记忆的刺激方案, 并辅以客观的脑电记录, 提高该类研究的有效性和可重复性, 最终达到提高工作记忆能力的目的。     

音乐对工作记忆影响及机制的ERP研究

以肖邦音乐为刺激材料,采用数字n-back实验范式来研究肖邦音乐对工作记忆的影响方式,并通过运用事件相关电位技术(ERP技术),研究不同音乐条件下,正常人大脑皮层的脑电活动情况,进而探讨音乐对工作记忆影响的神经机制。30名被试参加了3种音乐条件(无音乐、先导音乐、背景音乐)下的n-back(n=1、2)工作记忆任务的行为实验,收集行为数据;14名被试参加了同样实验过程的ERP实验,记录脑电数据。行为结果发现音乐条件对工作记忆效果有显著影响,且先导音乐条件下记忆效果最好;脑电结果显示P3波幅随记忆负荷的增加呈下降趋势,高记忆负荷水平下,P3波幅随先导音乐、背景音乐、无音乐的顺序逐渐呈现下降趋势;源定位分析发现音乐对工作记忆的促进作用可能跟大脑顶叶被激活有关。     

客体工作记忆研究的现状与展望

近年来, 大量的研究分别从行为和认知神经心理学的角度探讨了客体工作记忆的特性。行为水平上, 相关研究主要集中在客体工作记忆研究范式、客体在视觉工作记忆中的存储方式、视觉工作记忆容量等方面, 而客体工作记忆存储的争论体现在客体工作记忆存储的“强捆绑”假设、“特征-捆绑统一存储”假设、双重存储机制假设, 以及客体的捆绑等方面。认知神经水平上, 颞叶、枕叶和顶叶在视觉工作记忆中的作用不同, 顶叶、颞叶和前额叶在工作记忆特征捆绑和加工中起重要作用。     

右侧背外侧前额叶在视觉工作记忆中的因果性作用

以往的影像学研究表明右侧背外侧前额叶皮层(DLPFC)在视觉工作记忆中发挥重要作用, 然而缺乏因果性的证据。本研究旨在考察右侧DLPFC的激活与视觉工作记忆容量的因果关系, 并探讨这一关系受到记忆负荷的调节及其神经机制。被试接受经颅直流电刺激之后完成视觉工作记忆变化检测任务, 根据被试在虚假刺激情况下从负荷4到负荷6任务记忆容量的增量将被试分为低记忆增长潜力组(简称低潜力组)和高记忆增长潜力组(简称高潜力组), 结果发现正性电刺激右侧DLPFC相对于虚假电刺激显著提升了高潜力组被试在低记忆负荷(负荷4)下的记忆容量及其对应的提取阶段的脑电指标SPCN成分。表明右侧DLPFC在视觉工作记忆的提取阶段发挥重要的因果性作用; 正性经颅直流电刺激右侧DLPFC可使工作记忆容量高潜力被试获得更多的脑活动增益, 并导致更好的行为提升效果。     

视觉注意的顶叶神经机制

大脑皮层后顶叶是联合皮层的一部分。它前界体感区,后接视纹前皮层。传统上认为,脑的某些将感觉传入、概念和思想等一些不同的活动的神经信号联合起来的脑区称联合皮层。它是神经整合的高级中枢。灵长类后顶叶联合区与视觉注意密切相关。近年来,美国威斯康星大学神经生理系Yin,T·C·T.及其共同工作者应用微电极技术结合行为指标,在清醒猴上,记录了视觉注意时后顶叶皮层单个神经元活动特征。他们发现,下顶叶(7区)有4类神经元与视觉注意有关,其中三类不是通常意义的感觉或运动神经元。这些神经元是在动物注视着关心的目标物时才活动。Yin等设想,下顶叶对来自两个不同来源的信号进行整合,     

人类工作记忆的某些神经影像研究

采用神经影像技术研究人类工作记忆的脑机理是目前一个十分活跃的研究领域。研究表明存在负责不同信息加工的工作记忆系统 ,如词语工作记忆、空间工作记忆等 ,其中词语工作记忆主要由大脑左半球参与 ,空间工作记忆主要由大脑右半球参与。前额叶在工作记忆中的作用相当复杂 ,包括对记忆信息的注意和抑制、管理、整合等功能。合理巧妙的实验设计、多种研究手段的综合应用必将使人类工作记忆的脑机理得到充分阐明。     

认知事件相关电位P300与儿童青少年工作记忆的发展

研究采用ERP技术对59名儿童工作记忆水平与事件相关电位进行比较分析,以说明工作记忆发展的神经电生理基础及年龄特征。实验仪器为美国NICOLET公司生产的COMPACT FOUR脑诱发电位仪。结果发现:(1)儿童工作记忆水平与P300各成分潜伏期呈负相关,与P300各成分的振幅呈正相关。(2)儿童P300的各潜伏期随年龄增长而下降,振幅随年龄增长而增大。(3)不同性别儿童P300各成分均无显著性差异。     

孤独症谱系障碍者的视觉-空间工作记忆缺陷及脑机制

孤独症谱系障碍(ASD)个体存在视觉-空间工作记忆加工缺陷,主要表现在4个方面,即随认知负荷增大而缺陷加重、工作记忆容量不足、工作记忆加工过程中的注意功能失调和对刺激进行整体组织的能力缺乏。神经机制研究显示,ASD个体存在明显的额-顶工作记忆网络激活异常,以及相关脑区的脑结构、白质连接异常。另外,作为基础性的认知加工过程,ASD个体的视觉-空间工作记忆各加工环节与言语工作记忆、执行功能、社会认知等因素均存在交互影响。纵观目前研究成果,未来研究可从研究手段、机制探究和干预训练三方面入手,着眼于研究方法的生态化和多元化,揭示客体和空间工作记忆的机制分离,并着力开发更具针对性的干预训练模式。     

Dissociation of the neural systems for working memory maintenance of verbal and nonspatial visual information

Working memory for names and faces was investigated to ascertain whether verbal and nonspatial visual information is maintained in working memory by separate neural systems. The subjects performed a delayed match-to-sample task for famous or unfamous faces and names and a sensorimotor control task. Several occipital, temporal, parietal, and prefrontal areas were activated during all memory delays, in comparison with the control delays. Greater delay activity for unfamous faces than for names was obtained in the right fusiform gyrus, right inferior frontal gyrus (IFG), right IFG/ precentral gyrus, and right medial superior frontal gyrus, whereas greater delay activity for unfamous names than for faces was observed in the precuneus, left insula/postcentral gyrus, and left IFG/ precentral gyrus. There was no significant difference in the prefrontal activity in the comparison between famous faces and names. Greater delay activity for famous names than for faces was obtained in visual association and parietal areas. The results indicate that there is a functional dissociation based on information type within the neural system that is responsible for working memory maintenance of verbal and nonspatial visual information.     

The primate working memory networks

Working memory has long been associated with the prefrontal cortex, since damage to this brain area can critically impair the ability to maintain and update mnemonic information. Anatomical and physiological evidence suggests, however, that the prefrontal cortex is part of a broader network of interconnected brain areas involved in working memory. These include the parietal and temporal association areas of the cerebral cortex, cingulate and limbic areas, and subcortical structures such as the mediodorsal thalamus and the basal ganglia. Neurophysiological studies in primates confirm the involvement of areas beyond the frontal lobe and illustrate that working memory involves parallel, distributed neuronal networks. In this article, we review the current understanding of the anatomical organization of networks mediating working memory and the neural correlates of memory manifested in each of their nodes. The neural mechanisms of memory maintenance and the integrative role of the prefrontal cortex are also discussed.     

Self-reference during explicit memory retrieval: an event-related potential analysis

Is there a specific neurocognitive system underlying the subjective sense of having a unitary continuous self across time? If so, it should be possible to isolate functions involved in the sense of self from those supporting mental activities that the self is currently engaged in. We report a study of real-time noninvasive recordings of the brain's electrical activity (event-related potentials, ERPs). We found a common neural signature that is associated with self-referential processing regardless of whether subjects are retrieving general knowledge (noetic awareness) or reexperiencing past episodes (autonoetic awareness). These ERP data are consistent with models of autobiographical memory that postulate a single locus of control over explicit memory for various kinds of self-related information. The temporal properties and scalp distribution of this novel self-reference ERP effect also suggest that it may be a neurophysiological correlate of self-related activation in medial prefrontal and parietal neocortical circuits identified in functional magnetic resonance imaging experiments.     

工作记忆训练对认知功能和大脑神经系统的影响

工作记忆训练成为近年来提升个体认知绩效的一种有效方式。工作记忆训练主要是指采用工作记忆广度任务、刷新任务以及各种复杂工作记忆任务在计算机上以循序渐进的方式进行训练。近年来的研究发现, 工作记忆训练能提升工作记忆、流体智力、抑制、注意、阅读和数学等认知功能。神经机制的研究发现：工作记忆训练引起大脑额-顶区域激活减弱, 而皮层下结构包括纹状体和尾状核区域的激活增强; 工作记忆训练减少了大脑灰质的数量, 增强了大脑白质的功能连通性; 工作记忆训练引起尾状核上多巴胺受体的变化。未来的研究需要在研究设计、被试人群、研究手段上进一步确认和扩展工作记忆训练的有效性和内在认知神经机制。     

双特征空间客体捆绑关系的存储机制——来自ERP的证据

利用事件相关电位技术(ERPs),采用延迟匹配任务的实验范式,测查了16名正常被试完成位置客体、方向客体和位置—方向捆绑客体的工作记忆诱发的皮层慢电位。实验发现:在第1个客体呈现后的300ms到600ms之间,在顶叶皮层(CP5、P7、P3),位置客体、方向客体比捆绑客体诱发了一个更负的成分; 在右额(F4、FC6、FC2、F8)、右后颞(TP10)、左颞(T7)、左后颞(TP9)等脑区,捆绑客体比单一特征客体诱发出了一个更正的成分; 在800至1400ms的慢波成分上,位置和方向捆绑客体在F4、FC6和F8三个记录点诱发的波形比单一特征客体的波形波幅更正。右侧前额叶参与了客体整合表征的存储,该结果支持了情景缓冲器的假设。     

The effect of memory load on cortical activity in the spatial working memory circuit

Accumulating evidence from electrophysiology and neuroimaging studies suggests that spatial working memory is subserved by a network of frontal and parietal regions. In the present study, we parametrically varied the memory set size (one to four spatial locations) of a delayed-response task and applied time-resolved fMRI to study the influence of memory load upon the spatial working memory circuit. Our behavioral results showed that performance deteriorates (lower accuracy and longer reaction time) as memory load increases. Memory load influenced cortical activity during the cue, delay, and response phases of the delayed-response task. Although delay-related activity in many regions increased with increasing memory load, it also was significantly reduced in the middle frontal gyrus and frontal eye fields and leveled off in the parietal areas when memory load increased further. Delayrelated activity in the left posterior parietal cortex was also lower during the error trials, in comparison with the correct trials. Our findings indicate that the delay period activity in the spatial working memory circuit is load sensitive and that the attenuation of this signal is the neural manifestation of performance limitation in the face of excessive memory load.     

工作记忆的认知模型与神经机制

本文评述了工作记忆认知模型的进展,阐述工作记忆神经机制研究的基本问题。研究者在工作记忆认知模型框架下,提出了工作记忆成分结构的脑模型。根据自己的研究探索,展望进一步的研究问题,以及TMS和fMRI/ERP等脑成像技术的结合运用对工作记忆认知神经科学研究的推动。     

网络成瘾者工作记忆水平受影响的机制:来自ERP的证据

本研究采用事件相关电位技术(ERP),以N-back范式为实验任务,考察20名网络成瘾大学生和23名对照组大学生的工作记忆水平,结果发现:对照组的工作记忆具有一定加工优势的趋势,正确率高于成瘾组,反应时低于成瘾组,但均未达到显著差异。网络成瘾组与对照组工作记忆加工时,网络成瘾组P2波幅更高,N2波幅更低,N2潜伏期更长,说明与网络成瘾组相比,对照组工作记忆水平更高。     

Neural Bases of Human Working Memory

Working memory is the memory system that allows us to briefly keep information active, often so we can operate on it. Studies with rhesus monkeys first established that this system is partly mediated by neural mechanisms in the prefrontal cortex. Recently, there has been a substantial effort to study the neural bases of working memory in humans, using neuroimaging techniques such as positron emission tomography and functional magnetic resonance imaging. Some of the initial neuroimaging studies with humans focused on the neural mechanisms that mediate our ability to keep spatial information active. These results indicated that human spatial working memory is partly mediated by regions in parietal and prefrontal cortex. Subsequent research has shown that a different neural system is involved when people store object (rather than spatial) information, a difference similar to that found in monkeys.     

Neural activation pattern in self-deceivers

While deception is a conscious cognitive effort and self-deception is an unconscious cognitive effort. Such effort possibly shapes the working memory and generates a neural activation pattern in self-deception. Little attempt was made to identify activation pattern in self-deception. The present study investigated the phenomenon of self-deception by increasing the working memory functions using a boxcar design. functional magnetic resonance imaging (fMRI) revealed more activation in bilateral inferior parietal lobule (BA 40), superior parietal lobule (BA 7), middle frontal gyrus (BA 9), medial frontal gyrus (BA 6), thalamus and cerebellum. Activated areas in frontal and parietal cortex suggest significant role of working memory during self-deception.