spond during conflict trials. In fact the increase in reaction time (RT) 

 was about the same for the two species, but while humans rarely 

 made an error even after many hundreds of training trials, macaques 

 made errors at the rate of almost 25% on the conflict trials, sug- 

 gesting that their network for resolving conflict is not as efficient 

 (Washburn, 1994). We examined three conflict tasks, two of which 

 were suitable for children, using the same adults and MRI scanner 

 to determine areas of activation (Fan et al., 2003). We found that 

 all three tasks had a common focus in the anterior cingulate and, in 

 addition, all activated similar areas of the lateral prefrontal cortex. 

 The more dorsal area of the anterior cingulate has been shown to 

 be active primarily in cognitive tasks like the Stroop. However, 

 when tasks have a more emotional component they activate a more 

 ventral part of the cingulate (Bush et al., 2000). We have argued 

 that these two areas are involved in regulation of cognitive and 

 emotional networks (see fig. 3). 



Connectivity 



A possible difference between humans and other primates is in 

 their control of cognition and emotion, and may lie in the close 

 connectivity that the cingulate has to other parts of the brain. As 

 illustrated in figure 3, the dorsal part of the anterior cingulate is 

 involved in the regulation of cognitive tasks, while the more ventral 

 part of the cingulate is involved in regulation of emotion. One way 

 to examine this issue is to image the structural connections of dif- 

 ferent parts of the cingulate using diffusion tensor imaging. This 

 form of imaging uses the diffusion of water molecules in particular 

 directions due to the presence of myelinated fibers. Thus it provides 

 a way of examining the physical connections present in the brains 

 of people. Diffusion tensor imaging was carried out while people 

 performed a conflict-related task, and it was found that the dorsal 

 part of the anterior cingulate cortex (ACC) was connected to cortical 

 areas of the parietal and frontal lobes, while the ventral part of the 

 ACC had strong connections to subcortical limbic areas (Posner et 

 al., 2006). 



Comparative anatomical studies point to important differences in 



