The effect of anxiety and hostility in silent mentation on localized cerebral glucose metabolism

Ten normal, wakeful, young (average age, 25.3 +/- 6.6 years) male subjects received positron emission tomographic (PET) scans 45 to 120 minutes after an infusion of D-[18 F]deoxyglucose in order to assess localized cerebral glucose metabolic rates during silent visual and other sensory imagery and cognitive mentation. The typescripts of the verbal reports, limited to 5 minutes, of this type of mentation (including free-associations to all the silent mental events), were blindly content-analyzed to provide objective measures of various kinds of anxiety and hostility. Many significant positive and negative correlations were found in medial cortical, lateral cortical, and subcortical gray matter, and white matter areas between the magnitude of the anxiety and hostility aroused in the silent mental processes and localized cerebral glucose metabolic rates. Clearly, energy consumption in the brain, as judged from localized glucose metabolic rates, is highly influenced by the quality and quantity of emotionally tinged private reveries and mental events occurring spontaneously within human subjects. Brain areas involved with the processing of language, sensation, cognition, memory, and emotional reactions appear to be involved especially in these significant correlations. The implications of such findings in the neurosciences and behavioral sciences are discussed.