Understanding Brain Mechanisms Involved in Autobiographical Memory

The overall objective of this project is to characterize the spatiotemporal dynamics of brain oscillations underpinning autobiographical memory (ABM) and the modulation of the memory network using non-invasive brain stimulation.

Inclusion Criteria:Cognitively-Unimpaired Younger and Older AdultsAge 18 to 35 years old (younger adults)Age 55+ years old (older adults)without any cognitive impairment (based on the Montreal Cognitive Assessment: MoCA)willing and capable to give informed consent for participation in the study after it has been thoroughly explained ablewilling to comply with all study requirements informed consent form was signedMild Cognitive Impairment (MCI) patientsAge 55+ years oldClinical Diagnosis of MCIConfirmation of diagnosis will be made by the study MD based on a holistic consideration of the participant's cognitive evaluation and historyMini-Mental State Examination (MMSE) ≥ 18 (Mild AD ≥ 21)CDR ≥ .5Demonstration or history of autobiographical memory impairmentsOn a stable dose of medications for memory loss including cholinesterase inhibitors (e.g. donepezil, rivastigmine) or memantine as defined as 6 consecutive weeks of treatment at an unchanging doseMinimum of completed 8th-grade educationwilling and capable to give informed consent for participation in the study after it has been thoroughly explained - note that to ensure this in the case of the MCI participants, a cut-off of MOCA score >18 will be appliedable and willing to comply with all study requirements informed consent form was signedExclusion Criteria:Cognitively-Unimpaired Younger and Older Adultsany cognitive impairment captured by the Montreal Cognitive Assessment (MoCA) - score < 26major psychiatric co-morbidity including major depressive disorder, schizophrenia, or psychosisblindness or other disabilities that prevent task performanceContraindication for undergoing MRIAny metal in the brain or skull (excluding dental fillings) or elsewhere in the body unless cleared by the responsible covering MD (e.g. MRI compatible joint replacement)Mild Cognitive Impairment (MCI) patientsAge < 55 years oldAny current diagnosis of a major psychiatric disorder (e.g., schizophrenia, bipolar disorder, major depressive disorder)Other than MCI, any history of other progressive or genetic neurologic disorder (e.g. Parkinson's disease, multiple sclerosis, tubular sclerosis) or acquired neurological disease (e.g. stroke, traumatic brain injury, tumor), including intracranial lesionsHistory of head trauma resulting in prolonged loss of consciousnessCurrent history of poorly controlled headaches including chronic medication for migraine preventionHistory of fainting spells of unknown or undetermined etiology that might constitute seizuresHistory of seizures, diagnosis of epilepsy, or immediate (1st-degree relative) family history of epilepsy with the exception of a single seizure of benign etiology (e.g. febrile seizures) in the judgment of a board-certified neurologistAny unstable medical condition or chronic (particularly) uncontrolled medical conditions that may cause a medical emergency in case of a provoked seizure (cardiac malformation, cardiac dysrhythmia, asthma, etc.) or study complicationcontraindications to tACS, as recorded on a standardized screening questionnaire, which include a reported seizure within the past two years, use of neuroactive drugs, self-reported presence of specific implanted medical devices (e.g., deep brain stimulator, medication infusion pump, cochlear implant, pacemaker, etc.), or the presence of any active dermatological condition, such as eczema, on the scalpContraindication for undergoing MRI or receiving tACSAny metal in the brain or skull (excluding dental fillings) or elsewhere in the body unless cleared by the responsible covering MD (e.g. MRI compatible joint replacement)Any devices such as a pacemaker, medication pump, nerve stimulator, TENS unit, ventriculoperitoneal shunt unless cleared by the responsible covering MD