Functional magnetic resonance imaging activity during the gradual acquisition and expression of paired-associate memory
Functional magnetic resonance imaging activity during the gradual acquisition and expression of paired-associate memory
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DOI：
10.1523/jneurosci.4935-04.2005
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发表时间：
2005-06-15
影响因子：
5.3
通讯作者：
Stark, CEL
中科院分区：
文献类型：
--
作者：
Law, JR;Flanery, MA;Stark, CEL
最近的神经生理学研究结果表明，猴子海马体的放电频率发生了巨大的变化，作为学习新的协会的功能。为了将这些发现扩展到人类，我们使用血氧水平依赖（BOLD）功能磁共振成像（fMRI）来检查学习类似联想任务时的大脑活动模式。我们观察到，在学习过程中，不仅在海马，而且在海马旁和右嗅周皮质的活动，双边，单调增加。此外，在整个内侧颞叶（MTL）记忆系统和几个额叶区域观察到与简单新奇信号相关的活动。在额顶叶网络中观察到了一种对比模式，在这种模式中，高水平的活动一直持续到很好地学习了这种联系，此时活动下降到基线。因此，我们发现，人类的联想学习伴随着整个MTL以及扣带皮层和额叶的BOLD fMRI活动的显著增加，这与猴子海马的神经生理学发现一致。海马和周围的MTL皮层表现出类似的联想学习和新奇信号的发现强烈反对的观点，有一个明确的分工，在MTL中，海马是必不可少的形成协会和皮层参与新奇检测。第二个实验通过展示基线任务难度对MTL活动的实质性影响来解决来自第一个实验的数据的一个引人注目的方面，该MTL活动能够将记忆活动呈现为“正”或“负”。"
Recent neurophysiological findings from the monkey hippocampus showed dramatic changes in the firing rate of individual hippocampal cells as a function of learning new associations. To extend these findings to humans, we used blood oxygenation level-dependent ( BOLD) functional magnetic resonance imaging ( fMRI) to examine the patterns of brain activity during learning of an analogous associative task. We observed bilateral, monotonic increases in activity during learning not only in the hippocampus but also in the parahippocampal and right perirhinal cortices. In addition, activity related to simple novelty signals was observed throughout the medial temporal lobe (MTL) memory system and in several frontal regions. A contrasting pattern was observed in a frontoparietal network in which a high level of activity was sustained until the association was well learned, at which point the activity decreased to baseline. Thus, we found that associative learning in humans is accompanied by striking increases in BOLD fMRI activity throughout the MTL as well as in the cingulate cortex and frontal lobe, consistent with neurophysiological findings in the monkey hippocampus. The finding that both the hippocampus and surrounding MTL cortex exhibited similar associative learning and novelty signals argues strongly against the view that there is a clear division of labor in the MTL in which the hippocampus is essential for forming associations and the cortex is involved in novelty detection. A second experiment addressed a striking aspect of the data from the first experiment by demonstrating a substantial effect of baseline task difficulty on MTL activity capable of rendering mnemonic activity as either "positive" or "negative."