The anterior cingulate cortex (ACC), on the medial surface of the frontal lobes of the brain, is widely believed to be involved in the regulation of attention. Beyond this, however, its specific contribution to cognition remains uncertain. One influential theory has interpreted activation within the ACC as reflecting 'selection-for-action', a set of processes that guide the selection of environmental objects as triggers of or targets for action. We have proposed an alternative hypothesis, in which the ACC serves not to exert top-down attentional control but instead to detect and signal the occurrence of conflicts in information processing. Here, to test this theory against the selection-for-action theory, we used functional magnetic resonance imaging to measure brain activation during performance of a task where, for a particular subset of trials, the strength of selection-for-action is inversely related to the degree of response conflict. Activity within the ACC was greater during trials featuring high levels of conflict (and weak selection-for-action) than during trials with low levels of conflict (and strong selection-for-action), providing evidence in favour of the conflict-monitoring account of ACC function.

Objective-To examine abnormal patterns of frontal cortical-subcortical activity in response to emotional stimuli in euthymic individuals with bipolar disorder type I in order to identify trait-like, pathophysiologic mechanisms of the disorder. We examined potential confounding effects of total psychotropic medication load and illness variables upon neural abnormalities.Method-We analyzed neural activity in 19 euthymic bipolar and 24 healthy individuals to mild and intense happy, fearful and neutral faces.Results-Relative to healthy individuals, bipolar subjects had significantly increased left striatal activity in response to mild happy faces (p < 0.05, corrected), decreased right dorsolateral prefrontal cortical (DLPFC) activity in response to neutral, mild and intense happy faces, and decreased left DLPFC activity in response to neutral, mild and intense fearful faces (p < 0.05, corrected). Bipolar and healthy individuals did not differ in amygdala activity in response to either emotion. In bipolar individuals, there was no significant association between medication load and abnormal activity in these regions, but a negative relationship between age of illness onset and amygdala activity in response to mild fearful faces (p = 0.007). Relative to those without comorbidities, bipolar individuals with comorbidities showed a trend increase in left striatal activity in response to mild happy faces.Conclusions-Abnormally increased striatal activity in response to potentially rewarding stimuli and decreased DLPFC activity in response to other emotionally salient stimuli may underlie mood instabilities in euthymic bipolar individuals, and are more apparent in those with comorbid diagnoses. No relationship between medication load and abnormal neural activity in bipolar individuals suggests that our findings may reflect pathophysiologic mechanisms of the illness rather than medication confounds. Future studies should examine whether this pattern of abnormal neural activity could distinguish bipolar from unipolar depression. Bipolar disorder is one of the most debilitating illnesses worldwide (1). Bipolar disorder type I, in particular, is characterized by abnormalities in psychosocial and cognitive function as well as emotion and mood regulation that can persist outside of episodes of mania and depression, during remission (2-6), and likely reflect pathophysiologic mechanisms of the illness (7) that are not mood state dependant. The research agenda for DSM-V emphasizes a need to translate basic and clinical neuroscience findings into a new classification system for all psychiatric disorders based upon pathophysiologic and etiological processes (8,9). Examining neural system abnormalities in euthymic individuals with bipolar disorder type I during paradigms specifically designed to measure emotion processing is therefore a first stage toward identifying biomarkers of bipolar disorder that reflect pathophysiologic neural mechanisms of the disorder (10). These, in turn, can then be included in future diagnostic cl...

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In a brain imaging study of children learning algebra, it is shown that the same regions are active in children solving equations as are active in experienced adults solving equations. As with adults, practice in symbol manipulation produces a reduced activation in prefrontal cortex area. However, unlike adults, practice seems also to produce a decrease in a parietal area that is holding an image of the equation. This finding suggests that adolescents' brain responses are more plastic and change more with practice. These results are integrated in a cognitive model that predicts both the behavioral and brain imaging results.T he study reported here integrates behavioral methods, functional brain imaging (functional MRI), and cognitive modeling to study how children learn to solve equations. In particular, the children were solving equations like the following: 7x ϩ 1 ϭ 29. Past research with adult college students (1) modeled algebra equation solving by the interaction of three cognitive modules in the adaptive control of thought-rational (ACT-R) cognitive architecture (2, 3). There was an imaginal module that held a representation of the equation and performed imagined transformations on the equations. There was a retrieval module that retrieved algebraic rules and arithmetic facts in the solution of this equation. Finally, there was a manual module that programmed the output of the answer by the hand. A region in the left parietal cortex, which has been associated with imagery (4-6) and spatial processing (7) in other studies, was found to correspond to the imaginal module. A region in the left prefrontal cortex, which has been associated with retrieval in other studies (8)(9)(10)(11)(12)(13)(14), was found to correspond to the retrieval module. Finally, a region in the left motor and sensory cortices, which controls the right hand, was found to correspond to the manual module.After having identified these regions in algebra equation solving, we performed a series of experiments to determine whether they were specifically involved in algebra or were also involved in nonmathematical information-processing tasks (1,15,16). Similar involvement of these regions was found in a nonmathematical isomorph of algebra (artificial algebra) (1). Subsequent research (15), in which college students practiced the isomorph, found a speed-up that could be accounted for entirely in terms of reduced retrieval time. This finding was reflected in reduced activation in the prefrontal region of interest. There was not a comparable reduction in either the motor or parietal region.The present research addresses the question of whether the brain activation patterns observed from adults will be shown in children learning algebra. Specifically, do children who are just learning equation solving show activation of the same regions as in adults' algebra (1) and will their improvement be explained in terms of reduction just in the prefrontal retrieval region shown in adults' artificial algebra learning (15)? There is reason to suspect that we...