Kebir O, Tabbane K
Unité de recherche processus cognitifs dans la pathologie psychiatrique, service de psychiatrie B, H. Razi, La Manouba, Tunisia.
Encephale. 2008 Jun;34(3):289-98. doi: 10.1016/j.encep.2006.12.008. Epub 2007 Oct 24.
Working memory refers to a limited capacity system for temporary storage and processing of information that is known to depend on the integrity of the prefrontal cortex. It has been classically described as composed of a "central executive" that performs control, selection and planning functions, and two "slave" systems: on the one hand, the phonological loop that holds verbal, speech-based representations, and on the other hand, the visuospatial sketchpad that manipulates spatial and object visual representations.
Studies in schizophrenia have used different tasks that tap different processes within the working memory. Despite the variety of measures, there is solid neuropsychological evidence that patients with schizophrenia demonstrate deficits in all subsystems of working memory. Several studies have shown no correlations between working memory deficits and age, gender, premorbid IQ, duration of disease or positive syndrome, but a correlation has been found with a low-educational level, and negative and disorganization symptoms. Neuroimaging studies have provided evidence of an involvement of the dorsolateral-prefrontal cortex during working memory performance. Many studies have demonstrated a functional deficit in this area. However, several recent studies have reported either equal or increased activation of the dorsolateral-prefrontal cortex in schizophrenia during working memory performance. Working memory deficits are present early in the course of schizophrenia and they have been shown to be consistently associated with reduced levels of elementary social skills and learning capacity. Unaffected relatives of individuals with schizophrenia and individuals diagnosed with schizotypal personality demonstrate deficits in tasks designed to measure working memory function. Working memory dysfunctions might be suitable candidate markers for vulnerability. Certain executive sub-processes seem to be the most heritable component of the working memory. Working memory deficits in schizophrenia may benefit from specific stimulation of receptors such as the dopaminergic D1 receptor, adrenergic alpha-2A receptor or nicotinic receptors. Few studies on the effect of antipsychotic medication on working memory in schizophrenia have been carried out and their results are highly variable. Atypical antipsychotic drugs, notably risperidone, have appeared to improve performance in working memory tasks. Cognitive exercises can improve working memory with a six-month persistent effect.
工作记忆是指一个容量有限的系统，用于临时存储和处理信息，已知其依赖于前额叶皮层的完整性。传统上，它被描述为由执行控制、选择和计划功能的“中央执行系统”以及两个“从属”系统组成：一方面是语音回路，用于保存基于言语的表征；另一方面是视觉空间画板，用于处理空间和物体的视觉表征。
针对精神分裂症的研究使用了不同的任务来探究工作记忆中的不同过程。尽管测量方法多种多样，但有确凿的神经心理学证据表明，精神分裂症患者在工作记忆的所有子系统中均表现出缺陷。多项研究表明，工作记忆缺陷与年龄、性别、病前智商、病程或阳性症状之间无相关性，但与低教育水平以及阴性和紊乱症状存在相关性。神经影像学研究提供了证据，表明背外侧前额叶皮层在工作记忆表现过程中会被激活。许多研究已证明该区域存在功能缺陷。然而，最近的几项研究报告称，在工作记忆表现过程中，精神分裂症患者的背外侧前额叶皮层激活程度要么相同，要么增加。工作记忆缺陷在精神分裂症病程早期就已出现，并且已被证明与基本社交技能和学习能力水平的降低始终相关。精神分裂症患者未受影响的亲属以及被诊断为分裂型人格障碍的个体在旨在测量工作记忆功能的任务中也表现出缺陷。工作记忆功能障碍可能是易感性的合适候选标志物。某些执行子过程似乎是工作记忆中最具遗传性的组成部分。精神分裂症患者的工作记忆缺陷可能受益于对特定受体的刺激，如多巴胺能D1受体、肾上腺素能α-2A受体或烟碱受体。关于抗精神病药物对精神分裂症患者工作记忆影响的研究较少，且结果差异很大。非典型抗精神病药物，尤其是利培酮，似乎能改善工作记忆任务中的表现。认知训练可以改善工作记忆，并具有持续六个月的效果。
