Functional anatomy of intrinsic alertness: evidence for a fronto-parietal-thalamic-brainstem network in the right hemisphere

Alertness, the most basic intensity aspect of attention, probably is a prer equisite for the more complex and capacity demanding domains of attention s electivity. Behaviorally, intrinsic alertness represents the internal (cogn itive) control of wakefulness and arousal; typical tasks to assess optimal levels of intrinsic alertness are simple reaction time measurements without preceding warning stimuli. Up until now only parts of the cerebral network subserving alertness have been revealed in animal, lesion, and functional imaging studies. Here, in a O-15-butanol PET activation study in 15 right-h anded young healthy male volunteers for this basic attention function we fo und an extended right hemisphere network including frontal (anterior cingul ate-dorsolateral cortical)-inferior parietal-thalamic (pulvinar and possibl y the reticular nucleus) and brainstem (ponto-mesencephalic tegmentum, poss ibly involving the locus coeruleus) structures, when subjects waited for an d rapidly responded to a centrally presented white dot by pressing a respon se key with the right-hand thumb. (C) 1999 Elsevier Science Ltd. All rights reserved.