Spectral Characteristics of Memory Transformation

Inclusion Criteria: * Age 18 years or older (2/3 of the final sample will be ≥60years of age) * No previous stroke, brain tumor, neurodegenerative disease, or trauma to the head * Ability to give consent for study participation * who have access to a personal computer with internet Exclusion Criteria: * • Pregnancy * Inability to use all ten fingers to type on a standard computer keyboard * Uncorrected vision, hindering perception of visual cues presented on a standard computer screen * Medication use at the time of study that may interfere with learning or the effect of tACS, including but not limited to carbamazepine, flunarizine, sulpiride, rivastigmine, dextromethorphan; * Neuromuscular disorders affecting hand and finger movements necessary for 10-finger keyboard typing * Presence of neurological or psychiatric disorders * Presence of scalp injury or disease * Prior history of seizures * Prior intracranial surgery * Prior brain radiotherapy * Prior history of intracranial tumor, intracranial infection, or cerebrovascular malformation * Metal in head or neck * Contraindications to MRI (such as severe claustrophobia, implanted medical devices)