Close
This site uses cookies

By using this site, you consent to our use of cookies. You can view our terms and conditions for more information.

Modeling the Effects of Post-Traumatic Stress on Hippocampal Volume

Authors
Ms. Briana Marie Smith
University of Washington ~ Psychology
Madison Chiu
University of Washington, United States of America
Cher Yang
University of Washington Seattle ~ Psychology
Dr. Catherine Sibert
University of Groningen ~ Artificial Intelligence
Prof. Andrea Stocco
University of Washington ~ University of Washington
Abstract

Post-Traumatic Stress Disorder (PTSD) is a psychiatric disorder often characterized by the unwanted re-experiencing of a traumatic event through nightmares, flashbacks, and/or intrusive memories. This paper presents a neurocomputational model using the ACT-R cognitive architecture that simulates intrusive memory retrieval following a potentially traumatic event (PTE) and derives predictions about hippocampus volume observed in PTSD. Memory intrusions were captured in the ACT-R Bayesian framework by weighting the posterior probability with an emotional intensity term I to capture the degree to which an event was perceived as dangerous or traumatic. It is hypothesized that (1) Increasing the intensity I of a PTE will increase the odds of memory intrusions; and (2) Increased intrusions will result in a concurrent decrease in hippocampal size. A series of simulations were run and it was found that I had a significant effect on the probability of experiencing traumatic memory intrusions following a PTE. The model also found that I was a significant predictor of hippocampal volume reduction, where the mean and range of simulated volume loss match results of existing meta-analysis. The authors believe that this is the first model to both describe traumatic memory retrieval and provide a mechanistic account of changes in hippocampal volume, capturing one plausible link between PTSD and hippocampus size.

Discussion
New
Questions Last updated 3 years ago

Hi, thanks for your presentation, very nice work! I found the implementation and explanation of the model very clear. I have two questions: 1. You increased the probability of recalling the traumatic memory by including an intensity value to the activation. I'm wondering if there could also be a change in the recall probability due to changes in...

Dr. Maarten van der Velde 0 comments

very interesting stuff! I was wondering whether you also have empirical data to support this idea that hippocampal volume decreases due to PTSD. And if so: could it be that those with a smaller hippocampus are more predisposed to PTSD? In addition, I was wondering why you chose a multiplicative effect of traumatic memories rather than, say, an add...

Dr. Marieke Van Vugt 0 comments
Thank you! Questions Last updated 3 years ago

Hi Briana, Many thanks for your presentation! It was very clear, and the project is very interesting. I have a few follow-up questions for you: 1) I understand why you would want to add a constant bias I(m) to encode the emotional intensity of specific memories (which you added as log(I(m)) in the computation of the total activation). However, I a...

Mr. Pierre Gianferrara 0 comments
Thank you! Last updated 3 years ago

Thank you for viewing my presentation of "Modeling the Effects of Post-Traumatic Stress on Hippocampal Volume." Please comment with any questions, ideas, and suggestions you may have about this project--all input is welcome. I look forward to hearing from you, Briana Smith

Ms. Briana Marie Smith 0 comments
Cite this as:

Smith, B., Chiu, M., Yang, Y., Sibert, C., & Stocco, A. (2020, July). Modeling the Effects of Post-Traumatic Stress on Hippocampal Volume. Paper presented at Virtual MathPsych/ICCM 2020. Via mathpsych.org/presentation/219.