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The relative metabolic demand of inhibition and excitation

By using the ( 14 C)2-deoxyglucose method 1 , inhibition has been shown to be a metabolically active process at the level of the synapse 2 , 3 . This is supported by recent results from magnetic resonance spectroscopy that related the changes in neuroenergetics occurring with functional activation t...

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Bibliographic Details
Published in:Nature (London) 2000-08, Vol.406 (6799), p.995-998
Main Authors: Waldvogel, Daniel, van Gelderen, Peter, Muellbacher, Wolf, Ziemann, Ulf, Immisch, Ilka, Hallett, Mark
Format: Article
Language:English
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Summary:By using the ( 14 C)2-deoxyglucose method 1 , inhibition has been shown to be a metabolically active process at the level of the synapse 2 , 3 . This is supported by recent results from magnetic resonance spectroscopy that related the changes in neuroenergetics occurring with functional activation to neurotransmitter cycling 4 . However, inhibitory synapses are less numerous and strategically better located than excitatory synapses, indicating that inhibition may be more efficient, and therefore less energy-consuming, than excitation. Here we test this hypothesis using event-related functional magnetic resonance imaging in volunteers whose motor cortex was inhibited during the no-go condition of a go/no-go task, as demonstrated by transcranial magnetic stimulation. Unlike excitation, inhibition evoked no measurable change in the blood-oxygenation-level-dependent signal in the motor cortex, indicating that inhibition is less metabolically demanding. Therefore, the ‘activation’ seen in functional imaging studies probably results from excitation rather than inhibition.
ISSN:0028-0836
1476-4687
DOI:10.1038/35023171