中国科学院心理健康重点实验室知识库

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 0 (48 Hz), alpha (8-13 Hz), and gamma (>30 Hz) waves. 0 waves mainly correspond to the temporal organization of memory items; gamma waves are related to information maintenance; alpha waves 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 0 burst stimulation (TBS) with stimulating frequency in 0 or gamma 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 0 and gamma 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.