Social information is thought to be processed by a specific set of neural circuits often referred to as the ‘social brain’ The figure shows localization in human brains of the relevant temporo-parietal junction orbitofrontal cortex in lateral (top) and medial (bottom) views.
Santiesteban et al. now show that low levels of direct current stimulation of the temporoparietal junction region improves control of self-other representations. (The electrical stimulation is two saline-soaked surface sponge electrodes driven by a battery driven constant low current stimulator). Here is their summary, followed by the abstract:
-OFC neurons respond to social visual stimul
-OFC neurons differentiate between socially defined classes of images
-OFC neurons signal the value of social information for making decisions
-More OFC neurons convey social information than fluid reward magnitude.
Primate evolution produced an increased capacity to respond flexibly to varying social contexts as well as expansion of the prefrontal cortex [1,2]. Despite this association, how prefrontal neurons respond to social information remains virtually unknown. People with damage to their orbitofrontal cortex (OFC) struggle to recognize facial expressions [3,4], make poor social judgments [5,6], and frequently make social faux pas [7,8]. Here we test explicitly whether neurons in primate OFC signal social information and, if so, how such signals compare with responses to primary fluid rewards. We find that OFC neurons distinguish images that belong to socially defined categories, such as female perinea and faces, as well as the social dominance of those faces. These modulations signaled both how much monkeys valued these pictures and their interest in continuing to view them. Far more neurons signaled social category than signaled fluid value, despite the stronger impact of fluid reward on monkeys’ choices. These findings indicate that OFC represents both the motivational value and attentional priority of other individuals, thus contributing to both the acquisition of information about others and subsequent social decisions. Our results betray a fundamental disconnect between preferences expressed through overt choice, which were primarily driven by the desire for more fluid, and preferential neuronal processing, which favored social computations.
