Neural mechanisms of learning and memory in the human medial temporal lobe
Abstract/Contents
- Abstract
- The medial temporal lobe is critical for enabling memory for the events of one's personal past. However, whether medial temporal lobe subregions perform shared or qualitatively distinct computations to support these memories is a topic of debate. One prominent theoretical perspective proposes that complementary behavioral expressions of memory for past events are enabled via the creation of separated versus overlapping neural representations for events that share similar elements, and that these representations are formed by the hippocampus and medial temporal lobe cortex, respectively. A wealth of empirical data has examined this proposal by asking whether these complementary behavioral expressions of memory are differentially linked to integrity and / or functional activation of the hippocampus and medial temporal lobe cortex. Here, we examined complementary medial temporal lobe computations through a different lens, and asked whether the degree of neural overlap in the hippocampus and medial temporal lobe cortex elicited by stimuli during encoding is differentially linked to the ability to recognize those stimuli in the future. We addressed this question with two experiments using converging methodologies. In Experiment 1 we used high-resolution functional magnetic resonance imaging and pattern similarity analyses to quantify neural overlap across the spatial topography in medial temporal lobe subregions during encoding. We found that the relationship between pattern similarity during encoding and subsequent memory dissociated across the hippocampus and medial temporal lobe cortex: later memory was linked to greater across-item pattern distinctiveness in the hippocampus, but to greater across-item pattern similarity in medial temporal lobe cortex. Additionally, by comparing neural patterns elicited by individual stimuli regardless of later memory for these stimuli, we found that perirhinal cortex and parahippocampal cortex exhibited differential content sensitivity for multiple stimulus categories, whereas the hippocampus failed to demonstrate such content sensitivity. In Experiment 2 we used intracranial electroencephalography to quantify neural overlap across the temporal evolution of population-level neural activity in medial temporal lobe subregions during encoding. We found that later memory was linked to greater across-item pattern distinctiveness in the hippocampus but not in medial temporal lobe cortex, and that the strength of these relationships was modulated by the demands on behavioral expressions of memory during retrieval. These data provide novel evidence for complementary learning mechanisms across the hippocampus and medial temporal lobe cortex, and suggest that these mechanisms operate across both spatial and temporal dimensions of neural codes.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | LaRocque, Karen Fossum |
|---|---|
| Associated with | Stanford University, Department of Psychology. |
| Primary advisor | Wagner, Anthony David |
| Thesis advisor | Wagner, Anthony David |
| Thesis advisor | Grill-Spector, Kalanit |
| Thesis advisor | McClelland, James L |
| Advisor | Grill-Spector, Kalanit |
| Advisor | McClelland, James L |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Karen Fossum LaRocque. |
|---|---|
| Note | Submitted to the Department of Psychology. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Karen Fossum LaRocque
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