Episodic memory provides a means by which we are able to reflect on the past, make decisions about the future, and form a learned identity. As a result, the episodic memory impairments that occur in healthy aging and neurodegenerative disease can be devastating. There are no current effective treatments for memory disorders of aging, partly because neural mechanisms for memory impairment are not fully understood. One limitation is our lack of mechanistic knowledge regarding the nature of recollection memory impairments. Recollection testing typically uses all-or-nothing measures of general success that fail to capture the extent to which memory includes specific details from the original episode. The goals of this project are (1) to better quantify recollection precision as distinct from general recollection success in healthy aging, (2) to identify the brain-network basis for recollection precision and success impairments in aging using fMRI, and (3) to test the causal role of these brain networks for recollection precision in older adults using network-targeted noninvasive brain stimulation. Our preliminary findings suggest that whereas recollection success does not differ for older compared to younger adults, recollection precision is significantly impaired in older adults. Furthermore, we have shown that targeted noninvasive stimulation of posterior hippocampal-cortical networks can effectively enhance recollection precision in young adults. This combined research and training plan will therefore merge fMRI assessments of recollection precision and success with innovative noninvasive stimulation methods, and will provide a multi-dimensional training experience for the applicant. Results from the proposed project will provide the first experimental test of the role of memory-related brain networks in recollection impairments caused by aging, and findings could inform the development of future treatments for age-related memory decline based on noninvasive stimulation.
The hippocampal-cortical networks that support episodic recollection in aging are poorly understood. The proposed project aims to address this gap by using network-targeted non-invasive stimulation in conjunction with a novel fMRI task to characterize two separate components of episodic recollection (precision and success) in aging. The results will demonstrate causal mechanisms supporting episodic recollection in aging and will have the potential to inform treatment for age-related memory decline.
| Kim, Sungshin; Nilakantan, Aneesha S; Hermiller, Molly S et al. (2018) Selective and coherent activity increases due to stimulation indicate functional distinctions between episodic memory networks. Sci Adv 4:eaar2768 |
| Nilakantan, Aneesha S; Bridge, Donna J; VanHaerents, Stephen et al. (2018) Distinguishing the precision of spatial recollection from its success: Evidence from healthy aging and unilateral mesial temporal lobe resection. Neuropsychologia 119:101-106 |
