Cavaco Sara, Anderson Steven W, Allen John S, Castro-Caldas Alexandre, Damasio Hanna
Department of Neurology, Division of Behavioral Neurology and Cognitive Neuroscience, University of Iowa Carver College of Medicine, Iowa, USA.
Brain. 2004 Aug;127(Pt 8):1853-67. doi: 10.1093/brain/awh208. Epub 2004 Jun 23.
The finding that patients with amnesia retain the ability to learn certain procedural skills has provided compelling evidence of multiple memory systems in the human brain, but the scope, defining features and ecological significance of the preserved mnemonic abilities have not yet been explored. Here, we tested the hypothesis that subjects with amnesia would be able to learn and retain a broad range of procedural skills, by examining their acquisition and retention performance on five novel experimental tasks. The tasks are based on real-world activities and encompass a broad range of perceptual-motor demands: (i) the weaving task involves weaving pieces of fabric from woollen strings, using a manual weaver's loom; (ii) the geometric figures task consists of tracing geometric figures with a stylus as they move horizontally across a touch screen monitor; (iii) the control stick task involves tracking a sequence of visual target locations using a joystick control; (iv) the pouring task consists of pouring 200 ml of water from a watering can into a series of graduated cylinders, from a point 20 cm above the cylinders; and (v) the spatial sequence task involves learning an ordered sequence of pushing five spatially distributed buttons without visual guidance. Ten chronic and stable amnesic subjects (nine with bilateral medial temporal lobe damage due to herpes simplex encephalitis or anoxia, and one with thalamic stroke) and 25 matching normal comparison subjects were tested on three occasions: initial learning at time 1; retention at time 2 (24 h later); and retention at time 3 (2 months later). Despite impaired declarative memory for the tasks, the amnesic subjects demonstrated acquisition and retention of the five skills; their learning slopes over repeated trials were comparable with those of comparison subjects. These findings indicate that preserved learning of complex perceptual-motor skills in patients with amnesia is a robust phenomenon, and that it can be demonstrated across a variety of conditions and perceptual-motor demands. The comparability of the tasks employed in this study with real-world activities highlights the potential application of this memory dissociation in the rehabilitation of patients with amnesia.
失忆症患者仍保留学习某些程序性技能的能力，这一发现为人类大脑中存在多个记忆系统提供了有力证据，但这些保留的记忆能力的范围、定义特征和生态学意义尚未得到探索。在此，我们通过考察失忆症患者在五项新颖实验任务中的习得和保持表现，来检验他们能够学习并保留广泛程序性技能的假设。这些任务基于现实世界的活动，涵盖了广泛的感知运动需求：（i）编织任务是使用手工织布机用毛线编织织物；（ii）几何图形任务是用触控笔在触摸屏显示器上水平移动时追踪几何图形；（iii）操纵杆任务是使用操纵杆控制追踪一系列视觉目标位置；（iv）倒水任务是从高于量筒20厘米的位置将200毫升水从喷壶倒入一系列量筒；（v）空间序列任务是在没有视觉引导的情况下学习按顺序按下五个空间分布的按钮。十名慢性稳定失忆症患者（九名因单纯疱疹性脑炎或缺氧导致双侧内侧颞叶损伤，一名丘脑中风患者）和25名匹配的正常对照受试者接受了三次测试：第一次测试时的初始学习；第二次测试时的保持（24小时后）；第三次测试时的保持（2个月后）。尽管失忆症患者对任务的陈述性记忆受损，但他们展示了这五项技能的习得和保持；他们在重复试验中的学习斜率与对照受试者相当。这些发现表明，失忆症患者保留复杂感知运动技能学习能力是一种稳健的现象，并且可以在各种条件和感知运动需求下得到证明。本研究中使用的任务与现实世界活动的可比性突出了这种记忆分离在失忆症患者康复中的潜在应用。
