A common cortical metric for spatial, temporal, and social distance.
Distance describes more than physical space: we speak of close friends and distant relatives, and of the near future and distant past. Did these ubiquitous spatial metaphors arise in language coincidentally or did they arise because they are rooted in a common neural computation? To address this question, we used statistical pattern recognition techniques to analyze human fMRI data. First, a machine learning algorithm was trained to discriminate patterns of fMRI responses based on relative egocentric distance within trials from one distance domain (e.g., photographs of objects relatively close to or far away from the viewer in spatial distance trials). Next, we tested whether the decision boundary generated from this training could distinguish brain responses according to relative egocentric distance within each of two separate distance domains (e.g., phrases referring to the immediate or more remote future within temporal distance trials; photographs of participants' friends or acquaintances within social distance trials). This procedure was repeated using all possible combinations of distance domains for training and testing the classifier. In all cases, above-chance decoding across distance domains was possible in the right inferior parietal lobule (IPL). Furthermore, the representational similarity structure within this brain area reflected participants' own judgments of spatial distance, temporal soon-ness, and social familiarity. Thus, the right IPL may contain a parsimonious encoding of proximity to self in spatial, temporal, and social frames of reference.
Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755.
Carolyn
C
Parkinson
Shari
S
Liu
Thalia
T
Wheatley
D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D001185:Artificial Intelligence; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000098:blood supply / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007600:Judgment / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D012929:Psychological Distance; D011930:Reaction Time; D013028:Space Perception / Q000502:physiology*; D011795:Surveys and Questionnaires; D055815:Young Adult
D010100:Oxygen
egocentric distance; inferior parietal lobule; multivoxel pattern analysis; psychological distance; social cognition; temporoparietal junction