工作记忆的认知神经机制

Cognitive and neural mechanisms underlying working memory

工作记忆是短时间维持和控制输入信息的能力,与各种认知功能密切相关。与长时记忆相比,工作记忆的容量和精度都极为有限。以往的研究对容量和精度的认知与计算模型等方面已经有较多的讨论,但关于哪种模型对行为的拟合效果最好、是否存在记忆物数量的上限等问题仍存在不同的观点。近年来,与工作记忆相关的脑区和神经机制研究取得了很多进展,但是在参与工作记忆的脑区、神经振荡和分子机制等多个方面,仍然存在激烈的争论。本文对上述的研究进展做了较全面的综述,尤其针对工作记忆的脑区机制提供了我们自己研究积累的证据。进一步阐明反映前馈信息的γ振荡和反馈信息的α/β振荡与感觉皮层和额顶网络信息传递过程的关系,可能对于揭示工作记忆的神经机制起到关键作用。今后深入研究工作记忆相关的分子机制,如多巴胺和血清素等神经递质系统在工作记忆中的作用,可能会推进我们对工作记忆认知神经机制的理解;加强工作记忆在精神分裂症、阿尔茨海默病等疾病诊断中的量化指标,为工作记忆的训练和增强提供潜在的应用价值。

Working memory(WM) refers to the process of temporally maintaining and manipulating input information. WM is the global workspace of cognitive functions, however, with severely restricted capacity and precision. Previous cognitive and computational models discussed the methods of calculating capacity and precision of WM and the reason why they are so limited. It still remains debated which model is the best across all datasets, and whether there exists upper limits of items. Besides, sensory cortices and the frontal-parietal loop are suggested to represent WM memorandum. Yet recently, the sensory recruitment hypothesis that posits an important role of sensory cortices in WM is strongly argued. Meanwhile, whether the prefrontal cortex shows sustained activity or bursting γ oscillations is intensely debated as well. In the future, disentangling the contribution to WM of feedforward γ vs feedback α/β oscillations, and/or dopamine vs serotonin systems, is critical for understanding the neural mechanisms underlying WM. It will further do help to recognize the basis for the psychiatric(e.g. schizophrenia) or neurological(e.g. Alzheimer’s disease) disorders, and potentially to develop effective training and intervening methods.