Searching for a baseline: functional imaging and the resting human brain.
Functional brain imaging in humans has revealed task-specific increases in brain activity that are associated with various mental activities. In the same studies, mysterious, task-independent decreases have also frequently been encountered, especially when the tasks of interest have been compared with a passive state, such as simple fixation or eyes closed. These decreases have raised the possibility that there might be a baseline or resting state of brain function involving a specific set of mental operations. We explore this possibility, including the manner in which we might define a baseline and the implications of such a baseline for our understanding of brain function.
Gusnard
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DA
The Mallinckrodt Institute of Radiology, Washington University, St Louis, Missouri 63110, USA.
Raichle
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ME
Raichle
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ME
D001921:Brain / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D002560:Cerebrovascular Circulation / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008606:Mental Processes / Q000502:physiology; D008959:Models, Neurological; D010101:Oxygen Consumption; D014055:Tomography, Emission-Computed