Division of Brain Sciences and Medical Research Council Clinical Sciences Centre, Imperial College London, London, United Kingdom.
Ann Neurol. 2014 Aug;76(2):241-51. doi: 10.1002/ana.24199. Epub 2014 Jul 2.
Episodic memory retrieval is reliant upon cognitive control systems, of which 2 have been identified with functional neuroimaging: a cingulo-opercular salience network (SN) and a frontoparietal executive network (EN). In Alzheimer's disease (AD), pathology is distributed throughout higher-order cortices. The hypotheses were that this frontoparietal pathology would impair activity associated with verbal memory recall; and that central cholinesterase inhibition (ChI) would modulate this, improving memory recall.
Functional magnetic resonance imaging was used to study normal participants and 2 patient groups: mild cognitive impairment (MCI) and AD. Activity within the EN and SN was observed during free recall of previously heard sentences, and related to measures of recall accuracy.
In normal subjects, trials with reduced recall were associated with greater activity in both the SN and EN. Better recall was associated with greater activity in medial regions of the default mode network. By comparison, AD patients showed attenuated responses in both the SN and EN compared with either controls or MCI patients, even after recall performance was matched between groups. Following ChI, AD patients showed no modulation of activity within the SN, but increased activity within the EN. There was also enhanced activity within regions associated with episodic and semantic memory during less successful recall, requiring greater cognitive control.
The results indicate that in AD, impaired responses of cognitive control networks during verbal memory recall are partly responsible for reduced recall performance. One action of symptom-modifying treatment is partially to reverse the abnormal function of frontoparietal cognitive control and temporal lobe memory networks.
情景记忆检索依赖于认知控制系统，其中有 2 个系统已通过功能神经影像学确认：扣带-脑岛突显网络（SN）和额顶执行网络（EN）。在阿尔茨海默病（AD）中，病理学分布于高级皮质。假设是额顶叶病理学将损害与言语记忆回忆相关的活动；而中枢胆碱酯酶抑制（ChI）将调节这种情况，改善记忆回忆。
使用功能磁共振成像研究正常参与者和 2 个患者组：轻度认知障碍（MCI）和 AD。在自由回忆先前听到的句子时观察到 EN 和 SN 内的活动，并与回忆准确性的测量相关。
在正常受试者中，回忆减少的试验与 SN 和 EN 中的活动增加有关。更好的回忆与默认模式网络内侧区域的更大活动相关。相比之下，AD 患者的 SN 和 EN 的反应与对照组或 MCI 患者相比明显减弱，即使在组间回忆表现匹配后也是如此。在 ChI 之后，AD 患者的 SN 内活动没有调节，但 EN 内的活动增加。在回忆不太成功时，与情景和语义记忆相关的区域也会出现增强的活动，这需要更大的认知控制。
结果表明，在 AD 中，言语记忆回忆期间认知控制网络的反应受损部分是导致回忆表现下降的原因。症状修饰治疗的一种作用是部分逆转额顶叶认知控制和颞叶记忆网络的异常功能。
