Max Planck Institute for Human Development, Otto Hahn Research Group on Associative Memory in Old Age, Berlin, Germany; Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
Neuroimage. 2019 Nov 1;201:116020. doi: 10.1016/j.neuroimage.2019.116020. Epub 2019 Jul 16.
Functional magnetic resonance imaging (MRI) studies have demonstrated a critical role of hippocampus and inferior frontal gyrus (IFG) in associative memory. Similarly, evidence from structural MRI studies suggests a relationship between gray-matter volume in these regions and associative memory. However, how brain volume and activity relate to each other during associative-memory formation remains unclear. Here, we used joint independent component analysis (jICA) to examine how gray-matter volume and brain activity would be associated during associative encoding, especially in medial-temporal lobe (MTL) and IFG. T1-weighted images were collected from 27 young adults, and functional MRI was employed during intentional encoding of object pairs. A subsequent recognition task tested participants' memory performance. Unimodal analyses using voxel-based morphometry revealed that participants with better associative memory showed larger gray-matter volume in left anterior hippocampus. Results from the jICA revealed one component that comprised a covariance pattern between gray-matter volume in anterior and posterior MTL and encoding-related activity in IFG. Our findings suggest that gray matter within the MTL modulates distally distinct parts of the associative encoding circuit, and extend previous studies that demonstrated MTL-IFG functional connectivity during associative memory tasks.
功能磁共振成像（fMRI）研究表明，海马体和下额叶（IFG）在联想记忆中起着关键作用。同样，结构磁共振成像研究的证据表明，这些区域的灰质体积与联想记忆之间存在关系。然而，在联想记忆形成过程中，大脑体积和活动如何相互关联仍不清楚。在这里，我们使用联合独立成分分析（jICA）来研究在联想编码过程中，灰质体积和大脑活动如何相互关联，特别是在内侧颞叶（MTL）和 IFG 中。从 27 名年轻成年人中收集 T1 加权图像，并在有意编码物体对时进行功能磁共振成像。随后的识别任务测试了参与者的记忆表现。使用基于体素的形态测量的单峰分析显示，具有更好联想记忆的参与者在左前海马体中具有更大的灰质体积。jICA 的结果显示了一个成分，该成分包含了 MTL 中前、后区灰质体积与 IFG 中与编码相关的活动之间的协方差模式。我们的研究结果表明，MTL 内的灰质调节了联想编码回路中远程不同的部分，并扩展了先前的研究，这些研究表明在联想记忆任务中 MTL-IFG 功能连接。
