Functional Neuroimaging Studies

Perhaps the most direct evidence of development of the anterior cingulate cortex and behavioral regulation comes from an fMRI study of children between the ages of 7 and 11 years and young adults. In that study, Casey showed an increase in MR signal intensity in the anterior cingulate cortex as a function of increased number of errors on a go-no go task (Fig. 4). This task required the subject to override a compelling response. Those individuals experiencing the most difficulty with this task showed increased activity in this region. However, in this study, only regions of the prefrontal cortex were examined; thus, again the question may be raised as to how specific this region is to behavioral regulation in children. Other regions including portions of the basal ganglia and projections to and from these regions may be likely candidates. Interestingly, this study demonstrated a dissociation of prefrontal regions from anterior cingulate cortex function, with ventral prefrontal regions correlating with accuracy and the anterior cingulate regions correlating with errors. Thus, whereas the anterior cingulate may index errors or response conflict, the

Figure 3 Reaction times during performance of an attention shifting task in children between the ages of 6 and 18 years as a function of the size of the anterior cingulate cortex.
Figure 4 Location, volume, and percent change in MR signal intensity as a function of the number of errors for the ventral prefrontal and anterior cingulate cortices.

ventral prefrontal region indexed the degree of conflict resolution on this task. A similar dissociation has been shown in dorsolateral prefrontal cortex and anterior cingulate cortex on a version of a Stroop task more recently by MacDonald and Carter at the University of Pittsburgh.

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Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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