Sorbonne Universités, INSERM, CNRS, Institut de la Vision, Paris, France.
Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Front Neural Circuits. 2019 Oct 29;13:69. doi: 10.3389/fncir.2019.00069. eCollection 2019.
Spatial navigation involves multiple cognitive processes including multisensory integration, visuospatial coding, memory, and decision-making. These functions are mediated by the interplay of cerebral structures that can be broadly separated into a posterior network (subserving visual and spatial processing) and an anterior network (dedicated to memory and navigation planning). Within these networks, areas such as the hippocampus (HC) are known to be affected by aging and to be associated with cognitive decline and navigation impairments. However, age-related changes in brain connectivity within the spatial navigation network remain to be investigated. For this purpose, we performed a neuroimaging study combining functional and structural connectivity analyses between cerebral regions involved in spatial navigation. Nineteen young (μ = 27 years, σ = 4.3; 10 F) and 22 older (μ = 73 years, σ = 4.1; 10 F) participants were examined in this study. Our analyses focused on the parahippocampal place area (PPA), the retrosplenial cortex (RSC), the occipital place area (OPA), and the projections into the visual cortex of central and peripheral visual fields, delineated from independent functional localizers. In addition, we segmented the HC and the medial prefrontal cortex (mPFC) from anatomical images. Our results show an age-related decrease in functional connectivity between low-visual areas and the HC, associated with an increase in functional connectivity between OPA and PPA in older participants compared to young subjects. Concerning the structural connectivity, we found age-related differences in white matter integrity within the navigation brain network, with the exception of the OPA. The OPA is known to be involved in egocentric navigation, as opposed to allocentric strategies which are more related to the hippocampal region. The increase in functional connectivity between the OPA and PPA may thus reflect a compensatory mechanism for the age-related alterations around the HC, favoring the use of the preserved structural network mediating egocentric navigation. Overall, these findings on age-related differences of functional and structural connectivity may help to elucidate the cerebral bases of spatial navigation deficits in healthy and pathological aging.
空间导航涉及多种认知过程，包括多感觉整合、视空间编码、记忆和决策。这些功能是由大脑结构的相互作用介导的，可以大致分为一个后网络（负责视觉和空间处理）和一个前网络（专门用于记忆和导航规划）。在这些网络中，海马体（HC）等区域已知会受到衰老的影响，并与认知能力下降和导航障碍有关。然而，空间导航网络中与年龄相关的脑连接变化仍有待研究。为此，我们进行了一项神经影像学研究，结合了参与空间导航的大脑区域的功能和结构连接分析。在这项研究中，我们检查了 19 名年轻参与者（μ=27 岁，σ=4.3；10 名女性）和 22 名年长参与者（μ=73 岁，σ=4.1；10 名女性）。我们的分析主要集中在旁海马区（PPA）、后扣带回皮层（RSC）、枕叶区（OPA）以及从中枢和外周视觉区到视觉皮层的投射，这些区域是从独立的功能定位器中划分出来的。此外，我们从解剖图像中分割出海马体和内侧前额叶皮层（mPFC）。我们的结果显示，与年轻参与者相比，年长参与者的低视觉区与 HC 之间的功能连接呈年龄相关性下降，而 OPA 与 PPA 之间的功能连接呈年龄相关性增加。关于结构连接，我们发现导航大脑网络内的白质完整性存在与年龄相关的差异，但 OPA 除外。OPA 被认为参与了自我中心导航，而不是与海马体区域更相关的非自我中心策略。OPA 与 PPA 之间功能连接的增加可能反映了 HC 周围与年龄相关的变化的补偿机制，有利于使用保留的结构网络来介导自我中心导航。总的来说，这些关于功能和结构连接与年龄相关差异的发现可能有助于阐明健康和病理性衰老中空间导航缺陷的大脑基础。
