A computational model of prefrontal control in free recall: Strategic memory use in the California Verbal Learning task
A computational model of prefrontal control in free recall: Strategic memory use in the California Verbal Learning task
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DOI：
10.1162/089892903322370744
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发表时间：
2003-08-15
影响因子：
3.2
通讯作者：
Lim, J
中科院分区：
文献类型：
--
作者：
Becker, S;Lim, J
几十年来，对脑损伤患者额叶功能的研究，以及最近使用功能脑成像对完整个体的研究，已经描绘了额叶皮层复杂的执行功能。然而，大脑实现这些功能的机制仍然知之甚少。在这里，我们提出了一个计算模型的前额叶皮层（PFC）的作用，在控制记忆的使用，可能有助于阐明的机制，额叶控制的一个方面：回忆策略的开发和部署。该模型解释了前额叶皮层和内侧颞叶在策略记忆使用中的相互作用。PFC使用内部衍生的性能测量自组织其自身的助记符代码。这些助记码通过在内侧颞叶记忆系统中偏置提取而充当提取线索。我们目前的数据从三个模拟实验，展示了战略编码和检索的自由回忆的分类列表的话。实验1比较了两个控制网络的模型的性能，以评估模型的各个组件的贡献。实验2比较了正常和frontally病变模型的性能，从几项研究中使用frontally完整和frontally病变的个人，以及正常，健康的个人在分开注意的条件下的数据。实验3比较了该模型在回忆阻塞和未阻塞的分类列表的单词的数据从Stuss等人。（1994）为控制和额叶病变的个人的表现。总的来说，我们的模型捕捉到了自由回忆任务中人类表现的一些方面：在所有试验中回忆的总单词和语义聚类得分的增加，与未封锁的相关项目列表相比，封锁的相关项目列表的优越性，以及正常和正面损伤模型在所有试验中的相似表现模式，损伤模型在所有测量中的整体表现较差。该模型也有一些缺点，鉴于此，我们建议扩展该模型，使更复杂的形式的战略控制。
Several decades of research into the function of the frontal lobes in brain-damaged patients, and more recently in intact individuals using function brain imaging, has delineated the complex executive functions of the frontal cortex. And yet, the mechanisms by which the brain achieves these functions remain poorly understood. Here, we present a computational model of the role of the prefrontal cortex (PFC) in controlled memory use that may help to shed light on the mechanisms underlying one aspect of frontal control: the development and deployment of recall strategies. The model accounts for interactions between the PFC and medial temporal lobe in strategic memory use. The PFC self-organizes its own mnemonic codes using internally derived performance measures. These mnemonic codes serve as retrieval cues by biasing retrieval in the medial temporal lobe memory system. We present data from three simulation experiments that demonstrate strategic encoding and retrieval in the free recall of categorized lists of words. Experiment 1 compares the performance of the model with two control networks to evaluate the contribution of various components of the model. Experiment 2 compares the performance of normal and frontally lesioned models to data from several studies using frontally intact and frontally lesioned individuals, as well as normal, healthy individuals under conditions of divided attention. Experiment 3 compares the model's performance on the recall of blocked and unblocked categorized lists of words to data from Stuss et al. (1994) for individuals with control and frontal lobe lesions. Overall, our model captures a number of aspects of human performance on free recall tasks: an increase in total words recalled and in semantic clustering scores across trials, superiority on blocked lists of related items compared to unblocked lists of related items, and similar patterns of performance across trials in the normal and frontally lesioned models, with poorer overall performance of the lesioned models on all measures. The model also has a number of shortcomings, in light of which we suggest extensions to the model that would enable more sophisticated forms of strategic control.