Neural Mechanisms for Reducing Interference During Episodic Memory Formation

Objective: The goal of the research studies is to understand how memories are formed for similar experiences such that interference (confusion) between these memories is minimized. Of particular interest is the role of the hippocampus (a brain region important for memory).

Participants: Healthy individuals from the University of Oregon and surrounding community will be recruited through fliers, emails, and advertisements. For some of the studies, individuals between 18-80 years of age will be recruited. For others, individuals between 18-35 will be recruited.

Design: All studies will involve studying and trying to remember various images (e.g., natural scenes) displayed on a computer screen. Memory decisions will be made and recorded using a computer keyboard or external button box. The similarity of images and/or the specific learning procedures (e.g., number of repetitions, order of study, etc.) will be manipulated. Experimental sessions will be conducted in behavioral testing rooms (with or without eye tracking equipment) and/or in an MRI scanner.

Outcomes: Measures of interest will include (a) behavioral responses, (b) fMRI measures of hemodynamic responses, and/or (c) gaze direction as measured by eye tracking equipment. Behavioral responses will consist of simple memory decisions, such as indicating whether or not an image has been seen before or trying to remember associations between images. fMRI data will be analyzed using multivariate pattern similarity analyses. Eye tracking data will be used to measure the specific spatial locations of images that participants fixate on.

Inclusion criteria

Participants in behavioral studies must be:

• healthy and between the ages of 18-35 years old
• native English speakers
• right-handed.

Participants in fMRI studies must be:

• healthy and between the ages of 18-80 years old
• native English speakers
• right-handed.

Exclusion criteria

For behavioral studies:

• Potential participants will be informed that use of psychoactive drugs, mental health disorders, and chronic or temporary sleep deficits (an average of less than 6 hours of sleep over the past month or less than 4 hours of sleep the night prior to the experimental session) are reasons for exclusion because of the potential influence on cognitive functioning.

For fMRI studies:

• For some sub-studies, individuals older than age 35 will be excluded because of potential differences in cognitive and brain function across age groups that are beyond the scope of the proposed studies.
• Individuals will be informed that use of psychoactive drugs, mental health disorders, and chronic or temporary sleep deficits (an average of less than 6 hours of sleep over the past month or less than 4 hours of sleep the night prior to the experimental session) are reasons for exclusion because of the potential influence on cognitive functioning.