2008 AFAR Research Grant: Compensatory Changes in Neural Recruitment with Age

Please give a brief summary of your AFAR research project.
Memory and many other cognition functions decline across the adult lifespan. However, measures of brain activity do not reflect a simple pattern of loss with age. Rather, functional MRI (fMRI) reveals flexibility in the neural response and even compensation with age; older adults recruit additional regions of the brain that are not used by young adults to perform the same tasks. My study will investigate how the prefrontal cortex responds differently with age, and whether older adults recruit the region in response to age-related changes to vision or memory. By manipulating the visual properties of pictures, I will assess the ways in which prefrontal cortex responds to the sensory and memory demands of the task. I will also explore how individual differences in motivation are related to the recruitment of prefrontal cortex with age.

What problems are you addressing and what specific questions will your research seek to answer?
Although several studies have identified potential compensatory activity in the brain, it is unclear how older adults are compensating, and under which conditions. My study will address:

• do visual conditions elicit compensation (greater prefrontal activity) in older adults?
• does successfully forming memory traces elicit compensation (greater prefrontal activity) in older adults, and does this occur apart from the visual demands (good or poor visual conditions) of the task?
• do older adults who have a greater sense of control over their memory compensate by recruiting additional brain regions, compared to older adults who feel less control (i.e., are there differences in motivation that distinguish those who compensate neurally from those who do not)?

What aspects of your project are most interesting from a scientific point of view?
Some studies have suggested that increased activity in the front of the brain is a response to poor vision that occurs with age. However, changes to vision and memory have not been directly compared. In this study I can compare the response of prefrontal cortex to visual and mnemonic (memory) demands. In addition, there is intriguing data about differences in behavior for older adults who feel a sense of control over their memory compared to those who do not. My study will explore whether these differences in behavior are also reflected in brain activity.

What are the implications of your research for age-related diseases and disorders?
Understanding the conditions under which older adults recruit additional neural resources will allow us to better understand the avenues available for compensation. For example, knowing which older adults compensate more (perhaps due to differences in motivation, or a sense of control over their memory abilities) or which task conditions elicit compensation (poor vision or good memory) will suggest when and how people harness additional cognitive resources. This could help inform training programs or instruction in helpful strategies to improve older adults' memory.

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