The ultimate goal of this study is to develop non-invasive, painless repetitive transcranial magnetic stimulation (rTMS) protocols to prevent cognitive decline in patients with mild cognitive impairment (MCI) and cognitively normal individuals at high risk of developing Alzheimer's disease (AD). Currently, 1 in 9 adults over the age of 65 have AD, which currently totals more than 5 million Americans and this number is expected to rise as high as 16 million by 2050. MCI is a clinical syndrome that represents the gray area between healthy aging and dementia. Those with amnestic MCI (aMCI) have memory problems more severe than normal for their age and education, but their symptoms are not as severe as those of people with AD. Patients with aMCI are at high risk for AD. Notably, roughly half of those with MCI will continue to progress and convert to clinical dementia within 3 years. Alternatively, it is also worthwhile to study cognitively healthy older adults who carry genes that may increase the risk of AD. The frequency of the human APOE gene ε4 allele increases in patients with AD and the ε4 allele is also associated with an earlier age of disease onset. Currently, there are no known therapies that can effectively modify the progression and hallmark symptoms of AD. Therefore, it is crucial to provide an early intervention in patients with aMCI to delay or prevent the progression to AD. More specifically, this project has two specific aims: 1. To plan personalized non-invasive brain stimulation location by brain Imaging with Magnetic Resonance Imaging (MRI) in Mild Cognitive Impairment (MCI) 2. To identify potential personalized cognitive enhancement strategy (such as dosage or patterns) of Transcranial Magnetic Stimulation (TMS) in MCI. Techniques to artificially and precisely stimulate brain tissue are increasingly recognized as valuable tools both in clinical practice and in cognitive neuroscience studies among healthy individuals and people with clinical conditions. With these practices, researchers can safely stimulate specific regions of the brain to explore causal relationships that comprise the brain's circuitry and modulate behavior.