The Dynamics of Representational Change Underlying Recall
Brown University
Summary
The goal of this clinical trial is to examine how repeated memory retrieval changes visual representations in the brain in healthy adult participants. Specifically, the study aims to determine whether repeated recall strengthens or transforms neural representations in visual cortex compared to a time-matched control condition. The main questions it aims to answer are: 1) Does repeated retrieval produce cumulative changes in visual cortical representations compared to a control condition matched for elapsed time? 2) Do these representational changes differ for simple spatial stimuli and complex natural images? Researchers will compare neural activity patterns during repeated retrieval to those during a control retrieval condition to determine whether repeated recall leads to systematic changes in representational structure beyond those attributable to the passage of time. Participants will: 1) complete two fMRI sessions. 2) Undergo a localizer session including anatomical imaging, population receptive field (pRF) mapping, and a visual category localizer task. 3) Study cue-stimulus pairs consisting of either simple spatial patterns or natural images. 4) Recall previously studied stimuli multiple times during repeated and control retrieval conditions while undergoing fMRI scanning. Brain activity patterns during study and recall will be compared to assess how repeated retrieval influences the structure and tuning of visual representations.
Description
Two fMRI sessions will be conducted per subject. In the localizer session, the investigators will collect anatomical images and fMRI data necessary to define visual areas in each individual's native brain space. In addition to two high-resolution anatomical images, two short functional tasks will be acquired from every participant: 1) population receptive field (pRF) mapping; 2) visual category localizer. The pRF mapping task will be several runs of a bar aperture drifting across the central 8 degrees of the visual field. This will allow us to estimate the retinotopic sensitivity of individual…
Eligibility
- Age range
- 18–40 years
- Sex
- All
- Healthy volunteers
- Yes
Exclusion Criteria: * Under the age of 18 or over the age of 40 * Does not live in the United States or is not a native speaker of English * Diagnosis of a neurological disorders, a history of head trauma, or diagnosis of psychiatric disorder * Imperfect and uncorrected visual acuity, color blindness, or imperfect hearing * Magnetically or mechanically activated implants or other untested metal implants * Claustrophobia
Interventions
- BehavioralVisual Memory Encoding and Retrieval Task During fMRI
Participants will study cue-stimulus associations and subsequently retrieve the associated stimuli while undergoing fMRI scanning. Retrieval will occur under two conditions: (1) repeated retrieval, in which stimuli are recalled five times, and (2) control retrieval, in which stimuli are recalled twice with timing matched to the repeated condition. Neural activity patterns during study and recall will be measured using BOLD fMRI.
Location
- Brown University Magnetic MRI Research FacilityProvidence, Rhode Island