Khader Patrick, Knoth Kathrin, Burke Michael, Ranganath Charan, Bien Siegfried, Rösler Frank
Philipps-University Marburg, Germany.
J Cogn Neurosci. 2007 Mar;19(3):493-512. doi: 10.1162/jocn.2007.19.3.493.
The present study investigated the neurophysiological processes underlying associative long-term memory retrieval of objects and spatial positions by means of a modified fan paradigm with cued recall and two neuroimaging methods (electroencephalogram [EEG] and functional magnetic resonance imaging). In an acquisition phase, either one stimulus or two stimuli became associated with a noun. During retrieval, probe stimuli comprising noun pairs were presented, and participants had to recall the respective associations and decided whether the nouns are linked to each other via a commonly associated stimulus. With this design, the quality and quantity of recalled associations was systematically varied, whereas the triggering stimuli and response requirements were held constant in all experimental conditions. Recall time proved to be directly related to the number of associations fanning out from a retrieval cue. Correspondingly, the hemodynamic response (blood oxygen level-dependent [BOLD] signal) and the amplitude of slow negative EEG potentials increased monotonically with the number of associations in both left anterior and bilateral posterior cortical areas. These effects were consistently observed with content-specific topographies for the two distinct materials. Furthermore, the multimethod approach revealed a close temporal link between response times and event-related slow potential changes on the one side and a close topographical and amplitude correspondence between slow potentials and BOLD signal changes on the other. The integrated results suggest that the neuronal dynamics of associative memory retrieval are equivalent for different types of associations, but that the structural basis is clearly content-specific.
本研究通过一种改良的扇形范式结合线索回忆以及两种神经成像方法（脑电图[EEG]和功能磁共振成像），探究了物体与空间位置的关联性长期记忆提取背后的神经生理过程。在习得阶段，一个刺激或两个刺激与一个名词建立关联。在检索阶段，呈现由名词对组成的探测刺激，参与者必须回忆相应的关联，并判断这些名词是否通过一个共同关联的刺激相互联系。采用这种设计，回忆关联的质量和数量会系统地变化，而触发刺激和反应要求在所有实验条件下保持不变。结果表明，回忆时间与从检索线索发散出的关联数量直接相关。相应地，在左前脑区和双侧后脑区，血液动力学反应（血氧水平依赖[BOLD]信号）和慢负性脑电电位的幅度均随关联数量单调增加。对于两种不同材料，在特定内容的地形图上均一致观察到了这些效应。此外，多方法研究揭示，一方面反应时间与事件相关慢电位变化之间存在紧密的时间联系，另一方面慢电位与BOLD信号变化之间存在紧密的地形和幅度对应关系。综合结果表明，不同类型关联的关联性记忆提取的神经元动力学是等效的，但结构基础明显具有内容特异性。
