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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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Published in: | Nature (London) 2000-08, Vol.406 (6799), p.995-998 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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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. |
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ISSN: | 0028-0836 1476-4687 |
DOI: | 10.1038/35023171 |