Louis Vinke^1,2, Francesca De Marneffe¹, Suhani Dheer¹, Baktash Babadi^1,2, Lee Cohen^1,2, Dan Fulford^3,4, Roger Tootell^2,5,6, Daphne Holt^1,2,6; ¹Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA, ²Harvard Medical School, Boston, MA, USA, ³Sargent College of Health and Rehabilitation Sciences, Boston University, Boston, MA, USA, ⁴Psychological and Brain Sciences, Boston University, Boston, MA, USA, ⁵Department of Radiology, Massachusetts General Hospital, Boston, MA, USA, ⁶Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital

The regulation and representation of personal space, defined as the space near the body into which others cannot intrude without eliciting discomfort, is a basic form of non-verbal social communication. Non-human primate neurophysiological studies and human fMRI studies have identified a frontoparietal-subcortical network of brain areas that responds to intrusions into this space. However, the modulation of this network when responding to threatening versus rewarding stimuli remains unclear. Thus, here we investigated whether activation within this personal space monitoring network is sensitive to the emotional valence of the intruding stimulus. 3T fMRI data were collected for 60 healthy control individuals (mean age: 35.1 yrs; 44 females) while they viewed 3D face images which appeared to move towards or away from the subject and displayed one of three emotional expressions: neutral, angry, or happy. Significant activation to the approach vs. withdrawal conditions (the “looming” contrast) was observed within independently-defined personal space network areas (superior parietal, inferior parietal sulcus, and ventral/dorsal premotor cortices), with looming activation absent within early visual areas. When comparing responses to angry, happy and neutral face images, significant differences were observed within the ventral premotor area, with angry faces eliciting a stronger looming response compared to happy or neutral faces. The ventral premotor (vPM) area is particularly sensitive to the valence of personal space intrusions. The vPM may be recruited during preparation of defensive actions that aim to protect the face and body from incoming threats, as vPM stimulation has been shown to elicit defensive movements. Thus these findings are consistent with prior evidence for a central role of this neural system in the protection of the body from danger, and also have implications for investigations of clinical populations who maintain abnormal interpersonal distances while also having deficits in perception of non-verbal social cues (e.g., facial expressions).

Acknowledgements: R01MH127265, P41EB015896, Jeanne and Gerhard Andlinger Fund for Innovation at MGH