Metabolic brain pattern of sustained auditory discrimination.

Positron emission tomography of [18F]-2-fluorodeoxyglucose was used to assess the functional brain activity of normal subjects while performing auditory discrimination (CPT), while receiving an identical set of tones as in CPT, but with the instructions that they were background noise, or while at rest. The present study: (1) confirms earlier findings of an association between the functional activity of the right midprefrontal cortex and the performance of auditory discrimination, (2) localizes this increase in right prefrontal cortex activity to the middle prefrontal gyrus; and (3) provides a framework of specific testable hypotheses for the evaluation of the importance of certain limbic and paralimbic areas in the biological determination of sustained attention to be addressed in future studies. The framework accounts for the now confirmed finding that the middle cingulate has lower metabolic activity in CPT than at rest, and new findings of alterations in temporal lobe processing of tones in response to attention.