Overview

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 study, non-invasive electric 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 goal of the research is to explore the contribution of motivation to memory performance by modulating MCC connectivity with transcranial direct current stimulation (tDCS) to provide the first causal evidence that experimentally induced motivation can improve memory performance. Since MCC has not been stimulated with tDCS before, we will test three different stimulation protocols and compare against a placebo. The stimulation protocols were computationally optimized for this project. The primary aim is to find the stimulation protocol most successful at improving memory performance. In order to elucidate the mechanisms behind these changes, effects of stimulation on motivation and network connectivity will be investigated. If indeed memory can be improved by increasing motivation and effort via stimulating MCC, this study will generate new insights into the motivational mechanisms of successful aging.

Eligibility

Inclusion Criteria:

• between the ages of 65 and 80
• normal or corrected to normal vision
• fluent in speaking, reading and understanding English
• right-handed

Exclusion Criteria:

• any metal implants that may cause harm through MRI scanning
• other metals that may interfere with obtaining MRI signals
• claustrophobic
• pregnancy
• history of neurological or psychiatric illnesses
• history of fainting, seizures or epilepsy
• history of migraines
• history of drug abuse
• learning disability
• intracranial lesion
• any prescription or regular medication except for birth control
• any uncontrolled medical condition
• skin disease or damage on scalp
• hair style or head dress that prevents electrode contact with the scalp
• any condition affecting agility of hands (e.g. acute or chronic tenosynovitis, active joint deformity of arthritic origin)