Spatial navigation is an essential task for living a safe, independent life. Spatial navigation skills decline in normal aging and become progressively impaired in patients with Alzheimer?s disease (AD)1,2, severely impacting their daily life function, independence, and health3. Despite the use of compensatory navigational tools like signs, maps, and verbal directions, supporting spatial navigation in older adults and those with age-associated neurodegenerative disease remains a challenge. A major impediment to designing interventions is the limited understanding of how spatial direction comprehension is affected by the normal aging process and neurodegenerative disease. The goal of this project is to determine how normal aging and age-associated neurodegenerative disease affect spatial direction comprehension, and to elucidate the neural mechanisms underpinning spatial direction comprehension in healthy young and older adults. Our primary hypothesis is that spatial direction comprehension is supported as a result of increased connectivity between regions of the brain dedicated to encoding individual formats (i.e.,visual scenes, arrows, and words), which will result in specific patterns of impairment among older adults and those with amnestic mild cognitive impairment (aMCI), a precursor to Alzheimer?s disease. We also hypothesize that the intraparietal sulcus (IPS) ? a region that encodes spatial directions with respect to the navigator's current facing direction ? will function as a hub by computing spatial directions from all representational formats, an idea which has been supported by recent advances in fMRI. To test these hypotheses, the candidate will employ converging methodologies from cognitive neuroscience, including advanced functional magnetic resonance imaging techniques (network neuroscience and functional connectivity), and behavioral assessment of healthy young adults and older adults, and patients with amnestic mild cognitive impairment (aMCI). This award will enable the candidate to learn critical new methodologies, which will help uncover the neural instantiation of spatial direction comprehension. Through research projects and training experiences, the candidate will apply these methodologies to test new hypotheses and questions about how spatial direction comprehension deteriorates in older adults and in patients with age-related dementias. This research proposal will be undertaken at the University of Florida ? an elite research institution with access to fMRI, a large population of older adults with and without age-related dementia, and experts in network neuroscience, neurology, and cognitive neuroscience. This award will also provide critical preliminary data that will be applied to an R01 proposal on supporting spatial navigation in older adults and those with Alzheimer?s disease and related dementias.
Spatial navigation, a fundamental human behavior which facilitates a safe and independent life, is among the first behaviors to decline in healthy aging and Alzheimer?s disease and related dementias, greatly contributing to poor health outcomes and a loss of independence in these populations. Supporting spatial navigation requires an understanding of how the brain constructs spatial representations from communication tools that convey spatial directions in abstracted forms (i.e., signs, maps, verbal directions, and global positioning systems). This proposal examines behavioral and neural properties of spatial direction comprehension, and how those properties are altered in older adults and individuals with amnestic mild cognitive impairment, providing a novel characterization of spatial function in the human brain.
