Inclusion Criteria:
* Subjects 25-80 years of age.
* Ability to understand and speak English, follow written and verbal instructions (English), and give informed consent (English), as assessed by study staff.
* Ability to comply with all the testing and study requirements, including the ability to independently use a video conferencing tool and the ability to independently use a computer to access the web.
* Ability to independently complete a daily, online intervention and outcome assessments using a web browser compatible with the intervention and assessment software on a reliable, internet-connected laptop or desktop computer.
Exclusion Criteria:
* Current, controlled (requiring treatment) or uncontrolled psychiatric diagnosis, including but not limited to posttraumatic stress disorder, psychosis, bipolar illness, pervasive developmental disorder, severe obsessive compulsive disorder, severe depressive or severe anxiety disorder, conduct disorder, attention-deficit/hyperactivity disorder, or other symptomatic manifestations that in the opinion of the Investigator may confound study data/assessments.
* Current, controlled (requiring treatment) or uncontrolled neurological diagnosis, including but not limited to Alzheimer's Disease, other dementias, mild cognitive impairment, Huntington's Disease, Parkinson's Disease, multiple sclerosis, stroke, epilepsy, aphasia, or other condition that in the opinion of the Investigator may confound study data/assessments.
* Any other medical condition in the last 90 days that in the opinion of the Investigator may confound study data/assessments.
* Has been under the care of a caretaker or has not been living independently in the last 90 days.
* In the last three years has used any of the following for more than two weeks continuously: Online courses, Online brain training programs
* Known sensitivity (such as headaches, dizziness, nausea) to bright, stimulating video displays.
* History of seizures (excluding febrile seizures), or significant motor or vocal tics, including but not limited to Tourette's Disorder and photo-sensitive epilepsy.
* Visual acuity that cannot be corrected that prevents or negatively impacts computer activity.
* Has participated in a clinical trial within 90 days prior to screening.
* Pregnancy or planning to become pregnant.
Additional Exclusion Criteria for Cohort B only:
* Unwillingness or inability to comply with imaging safety protocols.
* Metal implants or exposure to shrapnel.
* Left-handed or ambidextrous.
