Causal Role of the Aperiodic Signal for Working Memory

Working memory (WM) is the ability to hold relevant information in mind in the absence of sensory input. The capacity for WM is a foundation for cognitive control and higher cognitive function more broadly. Previous research demonstrated that during the delay period of WM tasks, oscillatory electrical activity in the prefrontal cortex in the theta-frequency band (4-8 Hz) increased in amplitude. However, other groups found that the slope of the aperiodic signal in the brain was positively correlated with individual differences in WM capacity. Since low-frequency power and a steeper slope of the aperiodic signal are confounded in many analyses, it is not clear whether the slope of the aperiodic signal or the amplitude of low-frequency oscillations underlie WM capacity. With many studies investigating the causal role of theta oscillations in WM, the purpose of this project is to investigate the role of the aperiodic signal in WM performance.

Inclusion Criteria: * Between the ages of 18 and 35 * Able to provide informed consent * Normal or corrected-to-normal vision * Willing to comply with all study procedures and be available for the duration of the study * Ability to speak, read and understand English without a translator * Not color-blind Exclusion Criteria: * ADHD/ADD (currently under treatment) * Neurological disorder and conditions * Medical or neurological illness or treatment for a medical disorder that could interfere with study participation, e.g., unstable cardiac disease, HIV/AIDS, malignancy, liver or renal impairment * Prior brain surgery * Any brain devices/implants, including cochlear implants and aneurysm clips * History of traumatic brain injury * (For females) Pregnant * Anything that, in the opinion of the investigator, would place the participant at increased risk or preclude the participant's full compliance with or completion of the study * Current use of medications know to produce specific EEG activity known to disrupt interpretations of the findings including but not limited to: benzodiazepines, antipsychotics, antiepileptics and central nervous system stimulants