非侵入性脑刺激技术在工作记忆研究中的应用

Application of Non-invasive Brain Stimulation Techniques in Working Memory Research

工作记忆是人类认知功能的核心组成部分,负责信息的短暂存储与加工,并在日常任务执行中发挥重要作用。工作记忆的缺陷会导致高级认知过程和发展障碍,并且随着个体年龄的增长,工作记忆能力往往会衰退。鉴于大脑具有可塑性的特点,非侵入性脑刺激(noninvasive brain stimulation,NIBS)已经被用于激活特定大脑区域,以改善工作记忆功能。目前的证据表明,NIBS有潜力成为改善工作记忆的有效工具,主要包括经颅磁刺激(transcranial magnetic stimulation,TMS)、经颅电刺激(transcranial electrical stimulation,tES)等。本文首先综述了工作记忆的神经生理基础,然后回顾了近年来NIBS在健康成人工作记忆干预中的应用,讨论了其在提升工作记忆方面的潜在效益和局限,为工作记忆的深入研究和临床转化提供一定参考。

Working memory is a core component of human cognitive functions,responsible for the temporary storage and manipulation of information,and plays a vital role in the execution of daily tasks.Working memory includes information encoding,maintenance,manipulation,and retrieval,with the underlying mechanisms corresponding to neural oscillations.The frequency bands most related to each step of working memory are θ(4-8 Hz),α(8-13 Hz),and γ(>30 Hz)waves.θ waves mainly correspond to the temporal organization of memory items;γ waves are related to information maintenance;αwaves indicate inhibition of irrelevant information.These neural oscillations can be regulated by external rhythmic stimulation,gradually synchronizing to the rhythm and phase of external stimulation.This phenomenon is called neural entrainment.Non-invasive brain stimulation(NIBS)can regulate working memory related neural oscillations through entrainment,and has the potential to become a method to enhance working memory performance.Another possible intervention approach to improve working memory is to enhance the excitability of key brain regions involved in working memory through NIBS.In this review,we reviewed more than 50 studies applying NIBS for working memory in healthy adults,including transcranial magnetic stimulation(TMS),transcranial direct current stimulation(tDCS),transcranial alternating current stimulation(tACS),and other NIBS techniques.In terms of research paradigm,working memory NIBS studies with healthy adults usually adopt classic working memory behavioral paradigms,e.g.,n-back tasks with numbers or space positions,Sternberg tasks,relatively few stimulating sessions,mainly focus on the simultaneous or short-term effects on behavioral performance.For stimulation sites,the prefrontal cortex(especially dorsolateral prefrontal cortex(DLPFC))is the most commonly choice for it’s a vital role in functions such as information maintenance and cognitive resource allocation.The parietal lobe(especially the intraparietal sulcus(IPS))also plays an important role in information maintenance and manipulation,and is the second common stimulation site after DLPFC.Studies targeting the temporal lobe,occipital lobe,and motor cortex are relatively limited.For stimulation methods,TMS studies mainly use repetitive TMS(rTMS)and θ burst stimulation(TBS)with stimulating frequency in θ or γ band,one-sided or bilateral prefrontal cortex as the stimulation site.The specific intervention effects may also depend on the phase of the neural oscillation that TMS targets.For tDCS studies,anodal stimulation of DLPFC or parietal lobe is widely utilized.The heterogeneous intervention effects such as relatively weak enhancement or impairment of working memory performance after intervention,may result from varied stimulation protocol or participants’factors(e.g.,small sample size,inconsistent baseline levels).For tACS studies,the most widely used stimulation frequencies are θ and γ bands,usually with in-phase manner,fixed or individualized frequencies.Enhancement of working memory performance has been reported for both settings,and the effects are also affected by stimulation parameters,task difficulty and baseline levels of participants.Transcranial random noise stimulation(tRNS),temporal interference stimulation(TIS),transcranial ultrasound stimulation(TUS)are emerging NIBS techniques,of which TIS and TUS can stimulate deep brain regions.Current studies modulating working memory based on these cutting-edge techniques are limited,but they have potential in mechanism exploration and clinical applications in working memory research.