Human topographical orientation: individual variability and neural mechanisms

在周围环境中定位的能力是人类最复杂的行为之一。一些研究表明，这种复杂性取决于环境因素，比如环境中有意义的地标的密度。其他研究表明，除了环境因素外，个体在使用某些环境信息时表现出的自发偏见也导致了这一现象的复杂性，从而导致个体在采用不同的定向策略方面存在很大的差异。虽然这两个因素都可能导致人类定向的复杂性，但有证据表明，无论他们所处的环境和他们可能使用的定向策略如何，个体的定向技能都是不同的。在目前的研究计划中，我们的目标是调查这样一种假设，即个人定向技能的这种可变性可能部分取决于那些已知负责人类定向的大脑区域的功能和完整性。为了实现这一目标，我们将利用虚拟现实环境，让年轻健康的参与者通过使用不同的定向策略来执行不同的导航任务。这将使我们能够在使用选择性定向策略时选择技能较差或较好的个人群体。这些个体将参与一系列神经成像项目，包括功能性磁共振成像（fMRI）和弥散张量成像（DTI）研究。fMRI研究将评估当个体使用选择性定向策略时，不同大脑区域的神经活动，以及这种神经活动与个体定向技能的关系。DTI研究将调查与定向有关的大脑区域的分子特性，以及它们的结构组织与个体使用不同定向策略的能力的可变性之间的关系。行为的可变性和神经机制的可变性之间的密切关系的证据将是解释人类取向的基本机制的重要信息来源。

The ability to orient in the surrounding is one of the most complex human behaviors. Some studies suggest that this complexity relies on environmental factors, such as the density of meaningful landmarks available within the environment. Other studies suggest that in addition to environmental factors, the spontaneous bias that individuals show in using certain environmental information contributes to the complexity of the phenomenon, resulting in a high variability across individuals in adopting different orientation strategies. Although both of these factors may contribute to the complexity of orientation in humans, there is evidence that individuals vary in their orientation skills irrespective of both the environment in which they move and the strategies that they may use for orientation. In the present research program, we aim to investigate the hypothesis that such variability in individual orientation skills may depend in part on the functionality and integrity of those brain regions known to be responsible for orientation in humans. To achieve this objective, we will make use of virtual reality environments in which young healthy participants will perform different navigational tasks by using different orientation strategies. This will allow us to select groups of individuals with poor or good skills in using selective orientation strategies. These groups of individuals will then participate in a series of neuroimaging projects including functional Magnetic Resonance Imaging (fMRI) and Diffusion Tensor Imaging (DTI) studies. The fMRI studies will assess the neural activity of different brain regions involved while individuals make use of selective orientation strategies, and how that neural activity relates to the individuals' orientation skills. The DTI studies will investigate the molecular properties of those brain regions involved in orientation, and how their structural organization relates to the variability observed across individuals in their ability to make use of different orientation strategies. The evidence of a strong relationship between variability in behavior and variability in neural mechanisms will be a critical source of information to explain the basic fundamental mechanisms of orientation in humans.