Biology subjects

Goldfarb, E. V.

Publications and source records attributed to Goldfarb, E. V..

3 recordsLinked to original sources

bioRxiv2026

Striatal habit system drives behavioral rigidity in PTSD

Core symptoms of posttraumatic stress disorder (PTSD) like safety seeking and avoidance have long been described as habitual. Although widespread theoretical accounts posit a relationship between these behaviors and striatal-mediated habits, or rigid stimulus-response (S-R) associations, this idea has yet to be tested. Here, we implement a new task design to investigate how S-R associations are acquired, how flexibly they can be remapped, and how sensitive they are to changes in outcome value for individuals with PTSD as compared to individuals who experienced trauma without developing PTSD (trauma-exposed controls; TC). We find that individuals with PTSD, compared to TC, exhibit several hallmarks of habitual behavior, including more rigid habit-like perseveration following response remapping, and, with more severe symptoms, continued perseveration following outcome devaluation. We also observe that the PTSD group acquired these S-R associations more slowly. Using functional magnetic resonance imaging, we find significant putamen engagement when learning S-R associations that was especially pronounced in PTSD and predicted later perseveration. Finally, computational models indicate that the PTSD group leveraged gradual trial-by-trial updating to learn and later update associations, whereas the TC group leaned more on a stable, consistent choice strategy, both of which explained later behavioral rigidity. In addition to distinguishing individuals with PTSD, these habit-related processes were also more pronounced for individuals with more severe symptoms. Together, these results provide the first empirical evidence for the role of habits in PTSD.

neuroscience↗

bioRxiv2025

Stress drives the hippocampus to prioritize statistical prediction over episodic encoding

The hippocampus plays a critical role in encoding individual experiences into episodic memory, while also detecting patterns shared across these experiences that allow us to anticipate future events via statistical learning. Acute stress is known to impact the hippocampus but may have opposite effects on these competing functions. That is, although stress impairs episodic encoding, it may instead enhance statistical learning. Using functional magnetic resonance imaging, we tested how stress influences the hippocampal pathways and subfields that support episodic encoding and statistical learning while participants performed a task that engaged both processes. Across several analyses, stress biased hippocampal processing in favour of statistical learning, suppressing pattern separation between events in the dentate gyrus and enhancing the representation of statistically predictive features. Furthermore, stress drove the hippocampal monosynaptic pathway to support statistical learning rather than episodic encoding during predictive situations. Together, these data suggest that acute stress elicits targeted, adaptive changes in hippocampal pathways which may facilitate predicting and responding to upcoming events.

neuroscience↗

bioRxiv2023

Hippocampal mechanisms support cortisol-induced memory enhancements

Stress can powerfully influence episodic memory, often enhancing memory encoding for emotionally salient information. These stress-induced memory enhancements stand at odds with demonstrations that stress and the stress-related hormone cortisol can negatively affect the hippocampus, a brain region important for episodic memory encoding. To resolve this apparent conflict and determine whether and how the hippocampus supports memory encoding under cortisol, we combined behavioral assays of associative memory, high-resolution functional magnetic resonance imaging (fMRI), and pharmacological manipulation of cortisol in a within-participant, double-blinded procedure. Hydrocortisone led to enhanced functional connectivity between hippocampal subregions, which predicted subsequent memory enhancements for emotional information. Cortisol also modified the relationship between hippocampal representations and memory: whereas hippocampal signatures of distinctiveness predicted memory under placebo, relative integration predicted memory under cortisol. Together, these data provide novel evidence that the human hippocampus contains the necessary machinery to support emotional memory enhancements under stress.

neuroscience↗