Inclusion Criteria:  age ≥ 55 years subjective cognitive complaints, defined as self-experienced persistent decline in cognitive capacity in comparison with a previously normal status and unrelated to an acute event Montreal Cognitive Assessment (MoCA) score suggestive of Mild Cognitive Impairment (MCI) status (i.e., < 26) English language fluency Wireless internet connection at home Willingness to travel to the San Francisco VA in northern California or UCLA in southern California for in-person assessments at baseline, after the 12-week interventions, and at the 36-week follow-up Capacity to provide informed consent or legally authorized representative consent and participant assent.  Exclusion Criteria:  current or past Axis I psychiatric disorders, or recent unstable medical or neurological disorders disabilities that prevent participation in on-line movement classes (e.g., primarily use wheel-chair, severe visual impairment that would limit ability to observe instructor's movement on screen or severe hearing impairment that would limit ability to hear instructor's directions) insufficient English proficiency limited life expectancy (i.e., enrolled in hospice, metastatic cancer) plan to travel for > 1 week during 12-week intervention period diagnosis of dementia per the DSM-5 MoCA score suggestive of dementia (i.e., <17) started dementia medication (cholinesterase inhibitor or memantine) in past 3 months or plans to start dementia medication during study period planning to start/change any psychoactive medication during study period current participation in another research study contraindications to magnetic resonance imaging (MRI), including claustrophobia severe enough to prevent MRI examination, presence of ferrometallic objects in the body that would interfere with MRI examination and/or cause a safety risk (e.g., pacemakers, implanted stimulators, pumps) prior or current training in with Tai Chi, PLIE, or other mind-body practices