Reconsolidation is the process where consolidated memories return to a malleable state and can be modified. The purpose of this dissertation was to examine factors that influence the reconsolidation of conditioned fear memories using a behavioural method, known as the post-retrieval extinction paradigm, across two separate studies. Fear potentiated startle (FPS) and skin conductance response (SCR) were used as measures of fear for both studies.
In Study 1, I investigated how the expectation for learning impacts the reconsolidation of conditioned fear memories. Testing took place over three consecutive days and expectation for learning was manipulated via verbal instructions prior to memory reactivation. On Day 1, participants underwent fear acquisition to two distinct spider images. On Day 2, participants were assigned to one of the following conditions: reactivation with expectation for learning condition (n = 16); a reactivation with no expectation for learning condition (n = 16); or a no reactivation condition (n = 16). All participants underwent extinction, and participants in the reactivation conditions had their memory for the conditioned stimulus (CS+) reactivated either with or without the verbal manipulation for the expectation for learning. On Day 3, fear was reinstated, and participants underwent re-extinction to examine if the manipulation on Day 2 affected the memory. Partially consistent with my predictions, I found limited evidence that the expectation for learning enhanced reconsolidation for FPS but not SCR.
In Study 2, I examined how the level of spider fear impacted the reconsolidation of conditioned fear memories. I also examined if the effects of reconsolidation generalized to similar stimuli (i.e., stimulus generalization). On Day 1, participants who were either high (n = 17) or low (n = 17) on spider fear underwent fear acquisition to a spider and a snake image, while a neutral image served as the CS-. On Day 2, participants viewed a single presentation of the spider and the neutral images to reactivate their memories. Participants then underwent extinction. On Day 3, fear was reinstated, and participants underwent re-extinction to examine if the effect of reactivation on memory. Fear generalization was measured via presentation of similar but distinct spider and snake images. These images were presented prior to and post-acquisition (Day 1) and on Day 3 following reinstatement. On the same days (1 and 3), a behavioural approach test (BAT) was used as a second measure of fear generalization to assess approach behaviour to novel spider stimuli. Inconsistent with my predictions, for FPS, participants with high levels of spider fear displayed a return of fear to the non-reactivated snake image, but not to the reactivated spider image. Conversely, I found the opposite effect for the low spider fear group as they displayed a return of fear to the reactivated spider image but not the snake image. For SCR, participants in both groups displayed a return of fear to the reactivated spider image but not the snake image. I did not find any evidence that reconsolidation increased approach behaviour for either group during the BAT. These findings suggest that memories with high levels of distress may undergo reconsolidation when fear is measured with FPS but not SCR. The inconsistent findings between the groups suggest that conditioned and natural memories may undergo reconsolidation differently.
The findings from both studies have potential theoretical implications for the understanding of the boundary conditions of reconsolidation and have potential implications for the application of reconsolidation in clinical contexts. Limitations and future directions are also discussed.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/42114 |
| Date | 11 May 2021 |
| Creators | Marinos, Julia |
| Contributors | Ashbaugh, Andrea |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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