Differential Valuation and Learning From Social and Nonsocial Cues in Borderline Personality Disorder.

BACKGROUND: Volatile interpersonal relationships are a core feature of borderline personality disorder (BPD) and lead to devastating disruption of patients' personal and professional lives. Quantitative models of social decision making and learning hold promise for defining the underlying mechanisms of this problem. In this study, we tested BPD and control subject weighting of social versus nonsocial information and their learning about choices under stable and volatile conditions. We compared behavior using quantitative models. METHODS: Subjects (n = 20 BPD, n = 23 control subjects) played an extended reward learning task with a partner (confederate) that requires learning about nonsocial and social cue reward probability (the social valuation task). Task experience was measured using language metrics: explicit emotions/beliefs, talk about the confederate, and implicit distress (using the previously established marker self-referentiality). Subjects' weighting of social and nonsocial cues was tested in mixed-effect regression models. Subjects' learning rates under stable and volatile conditions were modeled (Rescorla-Wagner approach) and group × condition interactions tested. RESULTS: Compared to control subjects, BPD subject debriefings included more mentions of the confederate and less distress language. BPD subjects also weighted social cues more heavily but had blunted learning responses to (nonsocial and social) volatility. CONCLUSIONS: This is the first report of patient behavior in the social valuation task. The results suggest that BPD subjects expect higher volatility than control subjects. These findings lay the groundwork for a neurocomputational dissection of social and nonsocial belief updating in BPD, which holds promise for the development of novel clinical interventions that more directly target pathophysiology.

Individuals with Borderline Personality Disorder show larger preferred social distance in live dyadic interactions.

Personal space regulation is a key component of effective social engagement. Personal space varies among individuals and with some mental health conditions. Simulated personal space intrusions in Borderline Personality Disorder (BPD) reveal larger preferred interpersonal distance in that setting. These findings led us to conduct the first test of live interpersonal distance preferences in symptoms in BPD. With direct observation of subjects' personal space behavior in the stop-distance paradigm, we found a 2-fold larger preferred interpersonal distance in BPD than control (n = 30, n = 23). We discuss this result in context of known biology and etiology of BPD. Future work is needed to identify neural circuits underlying personal space regulation in BPD, individual differences in preferred interpersonal distance in relation to specific symptoms and relationship to recovery status.

New mechanisms in memory storage: piRNAs and epigenetics.

In recent years, a greater understanding has emerged of the role epigenetic mechanisms play in the brain, not only during development, but also in mature neurons involved in long-term memory. The identification of spatially and temporally tuned epigenetic modification of genetic loci during memory storage has revealed the remarkably input-responsive, target-specific, and long-term nature of epigenetic regulation, but the underlying mechanisms have remained elusive. New insight into these mechanisms has come from the study of small RNAs, which have emerged as regulators that can confer sequence specificity to DNA- and chromatin-modifying processes. We discuss advances in the elucidation of the epigenetic mechanisms involved in long-term memory, focusing on the role of small RNAs, and in particular piwi-interacting RNAs (piRNAs), in the epigenetic regulation underlying memory storage.