Reciprocal suppression of regional cerebral blood flow during emotional versus higher cognitive processes: Implications for interactions between emotion and cognition

Brain mapping studies using dynamic imaging methods demonstrate areas where regional cerebral blood flow (rCBF) decreases, as well as areas where flow increases, during performance of various experimental tasks. Task specificity holds for both sets of cerebral blood flow changes (Delta CBF), respectively, providing the opportunity to investigate areas that become "deactivated" and "activated" in the experimental condition relative to the control state. Such data yield the intriguing observation that in areas implicated in emotional processing, such as the amygdala, the posteromedial orbital cortex, and the ventral anterior cingulate cortex, although flow increases as expected during specific emotion-related tasks, flow decreases during performance of some attentionally demanding, cognitive tasks. Conversely, in some of the areas that appear to subserve cognitive functions, such as the dorsal anterior cingulate and the dorsolateral prefrontal cortices, flow increases while performing attentionally demanding cognitive tasks, but decreases during some experimentally induced and pathological emotional states. Although the specific nature of such reciprocal patterns of regional Delta CBF remains unclear, they may reflect an important cross-modal interaction during mental operations. The possibility that neural activity is less active in areas required in emotional processing during some higher cognitive processes holds implications for the mechanisms underlying interactions between cognition and emotion. Furthermore, the possibility that neural activity in some cognitive-processing areas is suppressed during intense emotional states suggests mechanisms by which extreme fear or severe depression may interfere with cognitive performance.