Functional Neuroimaging of the Social Regulation of Emotion in Schizophrenia

Negative symptoms in schizophrenia are characterized by deficits in normative experiences and expression of emotion. Social anhedonia (diminished pleasure from social experiences) is one negative symptom that may impact patients’ motivation to engage in meaningful social relationships. Past research has begun to examine the mechanisms that underlie social anhedonia, but it is unclear how this lack of social interest may impact the typically positive effects of social buffering and social baseline theory whereby social support attenuates stress. The present pilot study examines how social affiliation through hand holding is related to subjective and neural threat processing, negative symptoms, and social functioning. Twenty-one participants (14 controls; 7 schizophrenia) developed social affiliation with a member of the research staff who served as the supportive partner during the threat task. Participants displayed greater subjective benefit to holding the hand of their partner during times of stress relative to being alone or with an anonymous experimenter, as indicated by self-reported increased positive valence and decreased arousal ratings. When examining the effects of group, hand holding, and their interaction on the neurological experience of threat during the fMRI task, the results were not significant. However, exploratory analyses identified preliminary data suggesting that controls experienced small relative increases in BOLD signal to threat when alone compared to being with the anonymous experimenter or their partner, whereas the schizophrenia group results indicated subtle relative decreases in BOLD signal to threat when alone compared to either of the hand holding conditions. Additionally, within the schizophrenia group, more positive valence in the partner condition was associated with less severe negative symptoms, better social functioning, and more social affiliation, whereas less arousal was correlated with more social affiliation. Our pilot study offers initial insights about the difficulties of building and using social affiliation and support through hand holding with individuals with schizophrenia during times of stress. Further research is necessary to clarify which types of support may be more or less beneficial to individuals with schizophrenia who may experience social anhedonia or paranoia with others that may challenge the otherwise positive effects of social buffering and maintaining a social baseline.

Assessing the Oxidative History of Miller Range Martian Meteorites

Miller Range (MIL) Martian meteorites are oxidized nakhlites. Early studies attribute their oxidation to reduction-oxidation reactions involving assimilated sulfate. I utilize the sulfur isotope and major element composition of the MIL pairs to assess their oxidative history. MIL sulfides display an average sulfur isotope composition that is different from Nakhla sulfate and sulfide. The sulfur isotope differences produce a mixing array between juvenile sulfur and mass-independent sulfur signatures, indicating assimilation of anomalous sulfur into the melt. I estimate an fO2 of QFM (+3.5 ± 0.4) and a sulfur content of 360 ppm ± 12 – 1300 ppm ± 50. With these results, I test the hypothesis of sulfate assimilation through models of charge balance, isotope mixing, and degassing of sulfur bearing compounds. I conclude that sulfate assimilation was significant in the oxidation of the MIL pairs but, additional oxidants were assimilated.