Social Network Size Affects Neural Circuits in Macaques

• Published in: Science (American Association for the Advancement of Science) Vol. 334; no. 6056; pp. 697 - 700
• Main Authors: Sallet, J., Mars, R. B., Noonan, M. P., Andersson, J. L., O'Reilly, J. X., Jbabdi, S., Croxson, P. L., Jenkinson, M., Miller, K. L., Rushworth, M. F. S.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 04.11.2011; The American Association for the Advancement of Science; American Association for the Advancement of Science (AAAS)
• Subjects: Anatomical correlates of behavior; Animal cognition; Animals; Behavioral neuroscience; Behavioral psychophysiology; Biological and medical sciences; Brain; Circuits; Cognitive science; Comparative Analysis; Correlation; cortex; Cortexes; Dominance; Female; Fundamental and applied biological sciences. Psychology; Gray matter; Gyrus Cinguli - anatomy & histology; Gyrus Cinguli - physiology; Hierarchy, Social; Jacobians; Macaca; Magnetic Resonance Imaging; Male; Monkeys; Monkeys & apes; Nerve Net; Neural conduction; neural networks; Neural Pathways; Neurology; Organ Size; Prefrontal cortex; Prefrontal Cortex - anatomy & histology; Prefrontal Cortex - physiology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Social Behavior; Social Cognition; Social Environment; Social evolution; Social groups; Social networking; Social networks; Social structures; Temporal Lobe - anatomy & histology; Temporal Lobe - physiology; Temporal logic; Social group; Grey matter; Central nervous system; Monkey; Group size; Social network; Temporal cortex; Macaca mulatta; Prefrontal cortex; Encephalon; Vertebrata; Mammalia; Social dominance; Animal; Primates; Simioidea; Morphometry
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.1210027

It has been suggested that variation in brain structure correlates with the sizes of individuals' social networks. Whether variation in social network size causes variation in brain structure, however, is unknown. To address this question, we neuroimaged 23 monkeys that had been living in social groups set to different sizes. Subject comparison revealed that living in larger groups caused increases in gray matter in mid-superior temporal sulcus and rostral prefrontal cortex and increased coupling of activity in frontal and temporal cortex. Social network size, therefore, contributes to changes both in brain structure and function. The changes have potential implications for an animal's success in a social context; gray matter differences in similar areas were also correlated with each animal's dominance within its social network.