(b) Attention

Author and date	Stimuli	Task	ACC activations	Findings
Gu and Han (2007) [38]	Images or cartoons of hands in pain or no pain.	Attend to pain cues or count hands in image.	aMCC	Greater functional connectivity to left inferior frontal cortex (top-down regulation) during vicarious pain. Pain-related activation in aMCC eliminated when attention was withdrawn from pain.
Gu et al. (2010) [35]	Images of limbs in pain or no pain.	Judge if it is painful or not painful and laterality.	aMCC	No difference in activation between painful and nonpainful stimuli or judgment types. Increased functional connectivity during vicarious pain with visual attention areas and anterior insula.
Fan and Han (2008) [49]	Images or cartoons of hands in pain or no pain.	Attend to pain cues or count hands in image.		Early differentiation between pain and no pain.