Derek J. Huffman, Ph.D. - US grants

Project Summary Our episodic memories?the autobiographical memories for the events of our lives?provide us with a rich sense of personal history. Memory-related disorders cause patients to progressively lose the ability to form new memories and to retrieve old memories, thus clouding their sense of personal history. Episodic memories can be decomposed into the constituent features that comprise an event?namely, the ?what?, ?where?, and ?when? components of the event. Theories of episodic memory attach significant importance to the memory for the spatial context in which an event takes place (i.e., ?where?). Decades of research have suggested that a network of brain regions are involved in processing spatial information, and body-based cues (e.g., leg movements, head rotations) have been shown to dramatically influence the neural representations of spatial information in the rodent brain. Moreover, body-based cues provide ecologically relevant information regarding both distance (e.g., the number of steps taken to traverse goal-relevant landmarks) and direction (e.g., body rotations along a navigated path); however, due to technological and physical limitations, the majority of laboratory-based experiments of spatial memory in humans have been conducted in the complete absence of body-based cues. Recent breakthrough in virtual reality technology will allow laboratory-based studies of human spatial memory to become immersive, thus better approximating real-world spatial memory. We will combine these cutting-edge virtual reality devices with advanced multivariate analysis of data from two complimentary non-invasive recording techniques?functional magnetic resonance imaging (MRI) and wireless scalp electroencephalography (EEG)?to study human spatial memory. Functional MRI will allow us to investigate representations within brain regions known to play a critical role in spatial memory (e.g., the hippocampus, thalamus, retrosplenial cortex, parahippocampal cortex), and our wireless scalp EEG device will allow us to record neural activity while participants actively navigate. Our results will provide a pivotal advancement in our understanding of the influence of body-based cues and of learning on spatial representations in the human brain. Moreover, our experiments will answer fundamental questions about how to best study human spatial memory in a laboratory setting, thus laying a foundation for understanding how to improve memory in health and in memory-related disorders.