Comparing social cognitive,non-social cognitive,and resting brain activity in chimpanzees (Pan troglodytes).
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文摘
The evolution of the human brain and cognition represents a long-standing question of biological anthropology. Skillful interaction with others has been proposed as a primary mover behind increased intelligence in primates Dunbar 1998). This study explores the origins of the neural bases of social cognition in humans, asking whether human patterns of social cognitive brain function are unique to our species, or shared with chimpanzees Pan troglodytes). Using [18F]-fluorodeoxyglucose positron emission tomography, chimpanzee brain function was assessed during a social cognition task, a non-social cognition task, and at rest. Two primary aims are to assess the degree to which social cognitive brain function is similar to resting brain function in chimpanzees, and to examine the neural correlates of chimpanzee social cognition. Similar patterns of function to those of humans would suggest that these social cognitive networks were present in our last common ancestor. Conversely, if patterns of activation differ, these species may have diverged in this regard. Chimpanzees performed a match-to-sample task with videos depicting conspecific behaviors with varying social complexity. Functional neuroimaging data obtained during these task conditions were compared with data from a non-social condition and a resting condition. These conditions were compared both qualitatively and on a voxel-by-voxel basis using paired t-tests. Like the resting state, social cognition in chimpanzees activates cortical midline structures, including the precuneus, posterior cingulate, and medial prefrontal cortex. Social cognition also activates the insula and amygdala； higher levels of social complexity activate the ventral striatum. At rest, these areas are active to a greater degree. Whole brain averages of each condition examined independently show the same cortical midline areas of greatest activation across all conditions. Rest, however, produces a higher maximum activation and a wider spread of intensity. This study bolsters previous findings that the resting state in chimpanzees is characterized by similar patterns of brain activity as that of humans, with cortical midline structures highly active, and shows that these areas consistently deactivate in a variety of task conditions much like the human default network. Further, these data demonstrate similarity in brain function during social cognition and at rest in chimpanzees.