Lateralized spatial and object memory encoding in entorhinal and perirhinal cortices
Lateralized spatial and object memory encoding in entorhinal and perirhinal cortices
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DOI：
10.1101/lm.1357309
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发表时间：
2009-07-01
影响因子：
2
通讯作者：
Martin, Alex
中科院分区：
文献类型：
--
作者：
Bellgowan, Patrick S. F.;Buffalo, Elizabeth A.;Martin, Alex
嗅周和内嗅皮层是内侧颞叶陈述性记忆系统的重要组成部分。然而，使用血氧水平依赖性（BOLD）功能性磁共振成像（fMRI）研究其特定功能时，磁化率信号丢失严重，导致时间信噪比（tSNR）较差，从而导致BOLD信号可检测性较弱。我们已经证明，更高的空间分辨率在z平面导致改善BOLD功能磁共振成像信号质量时，在前内侧颞叶使用16元件的表面线圈阵列在3 T（特斯拉）。利用这种技术，本研究调查的作用，前内侧颞叶，特别是内嗅和嗅周皮质，在对象和空间记忆。参与者观看了一系列分形图像，并被指示对物体的身份或位置进行编码。对象和空间识别记忆测试后，18秒的延迟。在物体和空间编码任务中，嗅周和内嗅皮层都是活跃的。在这两个区域中，物体编码偏向左半球，而空间编码偏向右半球。在再认记忆中也有类似的半球偏向。最近的动物研究表明，内嗅皮层的区域之间的空间与对象处理的功能分离。我们的研究结果表明，这种过程特异性的区别可能在人类大脑中表现为半球分工。
The perirhinal and entorhinal cortices are critical components of the medial temporal lobe (MTL) declarative memory system. Study of their specific functions using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI), however, has suffered from severe magnetic susceptibility signal dropout resulting in poor temporal signal-to-noise (tSNR) and thus weak BOLD signal detectability. We have demonstrated that higher spatial resolution in the z-plane leads to improved BOLD fMRI signal quality in the anterior medial temporal lobes when using a 16-element surface coil array at 3 T (Tesla). Using this technique, the present study investigated the roles of the anterior medial temporal lobe, particularly the entorhinal and perirhinal cortices, in both object and spatial memory. Participants viewed a series of fractal images and were instructed to encode either the object's identity or location. Object and spatial recognition memory were tested after 18-sec delays. Both the perirhinal and entorhinal cortices were active during the object and spatial encoding tasks. In both regions, object encoding was biased to the left hemisphere, whereas spatial encoding was biased to the right. A similar hemispheric bias was evident for recognition memory. Recent animal studies suggest functional dissociations among regions of the entorhinal cortex for spatial vs. object processing. Our findings suggest that this process-specific distinction may be expressed in the human brain as a hemispheric division of labor.