Regional Differences in the Coupling between Resting Cerebral Blood Flow and Metabolism may Indicate Action Preparedness as a Default State

Section of Neuropsychiatry, Department of Psychiatry and the Philadelphia Veterans Administration Medical Center, University of Pennsylvania, Philadelphia, PA 19104-4283, USA.
Cerebral Cortex (Impact Factor: 8.67). 07/2008; 19(2):375-82. DOI: 10.1093/cercor/bhn087
Source: PubMed


Although most functional neuroimaging studies examine task effects, interest intensifies in the "default" resting brain. Resting conditions show consistent regional activity, yet oxygen extraction fraction constancy across regions. We compared resting cerebral metabolic rates of glucose (CMRgl) measured with 18F-labeled 2-fluoro-2-deoxy-D-glucose to cerebral blood flow (CBF) 15O-H2O measures, using the same positron emission tomography scanner in 2 samples (n = 60 and 30) of healthy right-handed adults. Region to whole-brain ratios were calculated for 35 standard regions of interest, and compared between CBF and CMRgl to determine perfusion relative to metabolism. Primary visual and auditory areas showed coupling between CBF and CMRgl, limbic and subcortical regions--basal ganglia, thalamus and posterior fossa structures--were hyperperfused, whereas association cortices were hypoperfused. Hyperperfusion was higher in left than right hemisphere for most cortical and subcallosal limbic regions, but symmetric in cingulate, basal ganglia and somatomotor regions. Hyperperfused regions are perhaps those where activation is anticipated at short notice, whereas downstream cortical modulatory regions have longer "lead times" for deployment. The novel observation of systematic uncoupling of CBF and CMRgl may help elucidate the potential biological significance of the "default" resting state. Whether greater left hemispheric hyperperfusion reflects lateral dominance needs further examination.

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Available from: Joel H Greenberg, Oct 01, 2015
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    • "Thus, rather than arousal independently modulating valuation processes, it is the interaction of arousal and valence which seems to produce valuation biases. This fits with the neural and physiological literature highlighting the role of arousal in modulating attention to particular stimuli and action preparedness (Schutter et al., 2008; Gur et al., 2009), hence our proposal it may contribute to probabilistic expectancy biases (see section Probabilistic Computation). Based on this literature, we suggest this generally speaks against an independent effect of arousal on valuation processes. "
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    Frontiers in Human Neuroscience 09/2013; 7:508. DOI:10.3389/fnhum.2013.00508 · 2.99 Impact Factor
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    • "Increased oxygen consumption resulting from energetic impairment (lactate production, elevated lactate/pyruvate ratio) and neuronal excitation due to sustained glutamate release could increase cerebral perfusion to correct this oxygen and energy deficit. This, however, requires an intact coupling between metabolism and perfusion [50], which is known to be disturbed after severe TBI [34] and during sedation/anaesthesia [51]. "
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