The ability to navigate from one place to another is essential for a flourishing and autonomous human life. Cognitive scientists have long believed that navigation in humans and animals is guided by mental representations of the spatial structure of the world, which are referred to as ?cognitive maps? because they play a functional role that is similar to physical maps. Consistent with this idea, electrophysiologists have identified neurons in rodent brains that fire as a function of spatial variables that are essential elements of a cognitive map, such as location, distance, and heading direction, while cognitive neuroscientists have investigated possible neural correlates of cognitive maps in several regions of the human brain, including the hippocampal formation (HF) and the retrosplenial complex (RSC). Notably, these brain regions are also known to be essential for several important cognitive functions besides spatial navigation, including memory, imagination, and thinking about the future. However, despite this previous work, there remain two crucial gaps in our knowledge. First, we have an incomplete understanding of how cognitive maps are represented in the human brain. Behavioral studies indicate that our spatial knowledge is often fragmented, hierarchically organized, and distorted in multiple ways compared to metric truth, and we do not yet understand how these ?real? cognitive maps are represented in brain structures such as HF and RSC. Most notably, we do not understand how the brain divides environments into spatial parts (such as rooms within a building, or neighborhoods in a city), and how it then combines these parts into a larger whole. Second, we do not yet have a good theory of how spatial cognitive maps can be applied to non-spatial domains, thus allowing brain structures such as HF and RSC to mediate both spatial and nonspatial functions. The current project will address these issues by using advanced neuroimaging techniques, such as multivoxel pattern analysis and individual difference analyses to: (i) identify the neural mechanisms that allow the brain to encode subspaces within a larger space; (ii) delineate the neural processes by which subspaces representations are combined into a larger cognitive map, and (iii) understand how the principles underlying spatial cognitive maps can be applied to nonspatial domains. This project has the potential to make a major and sustained advance in the field by resolving longstanding questions about the cognitive and neural systems underlying spatial navigation, and by providing fundamental knowledge about how the brain mediates a wide range of basic cognitive functions, including not just navigation, but also semantic and episodic memory, prospective thinking, and reasoning.
This project aims to understand the neural mechanisms underlying spatial and nonspatial knowledge. The information gained from this research will be important for developing rehabilitation strategies in people with impaired sight, who often suffer from wayfinding difficulties. Moreover, because the brain regions that support spatial and nonspatial knowledge are involved in several kinds of memory, information about these systems is important for mitigating the memory problems and navigational challenges that occur when these systems are impacted by normal aging, stroke, and neurodegenerative diseases such as Alzheimer's dementia.
