Fundamental advancements in understanding successful aging are limited by the lack of causal, rather than just correlational methods to connect age-related changes in memory ability to changes in brain structure and function. In this project, non-invasive electrical brain stimulation will be used as a tool to create causal links between successful memory function in aging and brain structures associated with motivation. Recently, it was shown that a group of elderly, dubbed ?superagers?, are indistinguishable from young adults in memory performance and the structure of cortical limbic regions. A key superaging region is mid-cingulate cortex (MCC), a brain structure associated with motivation and tenacity. The MCC is a hub region that synchronizes information flow between three core brain networks: the salience network, associated with attention to affectively relevant cues; the frontoparietal control network, associated with executive control; and the default mode network, traditionally associated with memory. The goal of the research is to explore the contribution of motivation to memory performance by modulating MCC connectivity with non-invasive brain stimulation. This R21 project will combine prior research on superagers, prior functional magnetic resonance imaging (fMRI) research on network function, and expertise in transcranial direct current stimulation (tDCS) in two innovative studies spanning across three specific aims to provide the first causal evidence that experimentally induced motivation can improve memory performance.
Specific Aim 1 will examine how memory performance can best be influenced with tDCS by comparing three stimulation protocols against a placebo.
Specific Aims 2 and 3 will investigate the effects of stimulation on motivation and network connectivity, respectively. The protocol most effective in modulating memory performance will be used in a subsequent experiment in which fMRI is acquired during a memory task. This data will be used to investigate how increased resting-state connectivity and task-evoked activity of MCC correlate with motivation and memory function in older adults. If indeed memory can be improved by increasing motivation and effort via stimulating MCC, this project will generate new insights into the motivational mechanisms of successful aging.
Despite recent evidence of the role of motivation in successful aging, causal evidence is nonexistent. By combining transcranial direct current stimulation with neuroimaging, this project will determine if modulation of brain function via stimulation leads to improved motivation and memory in normal elderly adults. This will provide a novel understanding of the neurobiology of motivation in the service of successful aging.