Bidirectional signal exchanges and their mechanisms during joint attention interaction - A hyperscanning fMRI study.

Social interactions are essential to our daily life. We tested the hypothesis that social interactions during joint attention (JA) require bidirectional communication, each with a different mechanism. We used a novel multivariate functional connectivity analysis, which enables obtaining directed pathways between four regions at each time-frequency point, with hyper-scanning MRI data of real-time JA interaction. Constructing multiple "4-regional directed pathways" and counting the number of times, regions engaged in feedforward or feedback processes in the 'sender' or the 'receiver brains, we obtained the following. (1) There were more regions in feedforward than in feedback processes (125 versus 99). (2) The right hemisphere was more involved in feedforward (74 versus 33), while the left hemisphere in feedback (66 versus 51). (3) The dmPFC was more engaged in feedforward (73 versus 44) while the TPJ in both (49 versus 45). (4) The dmPFC was more involved in the sending processes (i.e. initiation of feedforward and feedback) while the TPJ in the receiving processes. (5) JA interaction was involved with high MRI frequencies (0.04-0.1 Hz), while continues interactions by low MRI frequencies (0.01-0.04 Hz). (6) Initiation and responding to JA (i.e. IJA and RJA) evolved with composite neural systems: similar systems for pathways that included the dmPFC, vmPFC and the STS, and different systems for pathways that included the TPJ, vmPFC, PCC and the STS. These findings have important consequences in the basic understanding of social interaction and could help in diagnose and follow-up of social impairments.

Neural responses to instructed positive couple interaction: an fMRI study on compliment sharing.

Love is probably the most fascinating feeling that a person ever experiences. However, little is known about what is happening in the brains of a romantic couple-the central and most salient relationship during adult age-while they are particularly tender and exchanging loving words with one another. To gain insight into nearly natural couple interaction, we collected data from N = 84 individuals (including N = 43 heterosexual couples) simultaneously in two functional magnetic resonance imaging scanners, while they sent and received compliments, i.e. short messages about what they liked about each other and their relationship. Activation patterns during compliment sharing in the individuals revealed a broad pattern of activated brain areas known to be involved in empathy and reward processing. Notably, the ventral striatum, including parts of the putamen, was activated particularly when selecting messages for the partner. This provides initial evidence that giving a verbal treat to a romantic partner seems to involve neural reward circuitry in the basal ganglia. These results can have important implications for the neurobiological mechanisms protecting and stabilizing romantic relationships, which build a highly relevant aspect of human life and health.

Deficient Amygdala Habituation to Threatening Stimuli in Borderline Personality Disorder Relates to Adverse Childhood Experiences.

BACKGROUND: Heightened amygdala response to threatening cues has been repeatedly observed in borderline personality disorder (BPD). A previous report linked hyperactivation to deficient amygdala habituation to repeated stimuli, but the biological underpinnings are incompletely understood. METHODS: We examined a sample of 120 patients with BPD and 115 healthy control subjects with a well-established functional magnetic resonance imaging emotional face processing task to replicate the previously reported amygdala habituation deficit in BPD and probed this neural phenotype for associations with symptom severity and early social risk exposure. RESULTS: Our results confirm a significant reduction in amygdala habituation to repeated negative stimuli in BPD (pFWE = .015, peak-level familywise error [FWE] corrected for region of interest). Post hoc comparison and regression analysis did not suggest a role for BPD clinical state (pFWE > .56) or symptom severity (pFWE > .45) for this phenotype. Furthermore, deficient amygdala habituation was significantly related to increased exposure to adverse childhood experiences (pFWE = .013, region of interest corrected). CONCLUSIONS: Our data replicate a prior report on deficient amygdala habituation in BPD and link this neural phenotype to early adversity, a well-established social environmental risk factor for emotion dysregulation and psychiatric illness.

State-Dependent Cross-Brain Information Flow in Borderline Personality Disorder.

Importance: Although borderline personality disorder (BPD)-one of the most common, burdensome, and costly psychiatric conditions-is characterized by repeated interpersonal conflict and instable relationships, the neurobiological mechanism of social interactive deficits remains poorly understood. Objective: To apply recent advancements in the investigation of 2-person human social interaction to investigate interaction difficulties among people with BPD. Design, Setting, and Participants: Cross-brain information flow in BPD was examined from May 25, 2012, to December 4, 2015, in pairs of participants studied in 2 linked functional magnetic resonance imaging scanners in a university setting. Participants performed a joint attention task. Each pair included a healthy control individual (HC) and either a patient currently fulfilling DSM-IV criteria for BPD (cBPD) (n = 23), a patient in remission for 2 years or more (rBPD) (n = 17), or a second HC (n = 20). Groups were matched for age and educational level. Main Outcomes and Measures: A measure of cross-brain neural coupling was computed following previously published work to indicate synchronized flow between right temporoparietal junction networks (previously shown to host neural coupling abilities in health). This measure is derived from an independent component analysis contrasting the time courses of components between pairs of truly interacting participants compared with bootstrapped control pairs. Results: In the sample including 23 women with cBPD (mean [SD] age, 26.8 [5.7] years), 17 women with rBPD (mean [SD] age, 28.5 [4.3] years), and 80 HCs (mean [SD] age, 24.0 [3.4] years]) investigated as dyads, neural coupling was found to be associated with disorder state (η2 = 0.17; P = .007): while HC-HC pairs showed synchronized neural responses, cBPD-HC pairs exhibited significantly lower neural coupling just above permutation-based data levels (η2 = 0.16; P = .009). No difference was found between neural coupling in rBPD-HC and HC-HC pairs. The neural coupling in patients was significantly associated with childhood adversity (T = 2.3; P = .03). Conclusions and Relevance: This study provides a neural correlate for a core diagnostic and clinical feature of BPD. Results indicate that hyperscanning may deliver state-associated biomarkers for clinical social neuroscience. In addition, at least some neural deficits of BPD may be more reversible than is currently assumed for personality disorders.