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Citation
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HERO ID
7796519
Reference Type
Journal Article
Title
Functional MRI of calcium-dependent synaptic activity: cross correlation with CBF and BOLD measurements
Author(s)
Duong, TQ; Silva, AC; Lee, SP; Kim, SG
Year
2000
Is Peer Reviewed?
1
Journal
Magnetic Resonance in Medicine
ISSN:
0740-3194
EISSN:
1522-2594
Volume
43
Issue
3
Page Numbers
383-392
Language
English
PMID
10725881
DOI
10.1002/(sici)1522-2594(200003)43:3<383::aid-mrm10>3.0.co;2-q
Web of Science Id
WOS:000085559100010
URL
http://
://WOS:000085559100010
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Abstract
Spatial specificities of the calcium-dependent synaptic activity, hemodynamic-based blood oxygenation level-dependent (BOLD) and cerebral blood flow (CBF) fMRI were quantitatively compared in the same animals. Calcium-dependent synaptic activity was imaged by exploiting the manganese ion (Mn++) as a calcium analog and an MRI contrast agent at 9.4 T. Following forepaw stimulation in alpha-chloralose anesthetized rat, water T1 of the contralateral forepaw somatosensory cortex (SI) was focally and markedly reduced from 1.99 +/- 0.03 sec to 1.30 +/- 0.18 sec (mean +/- SD, N = 7), resulting from the preferential intracellular Mn++ accumulation. Based on an in vitro calibration, the estimated contralateral somatosensory cortex [Mn++] was approximately 100M, which was 2-5-fold higher than the neighboring tissue and the ipsilateral SI. Regions with the highest calcium activities were localized around cortical layer IV. Stimulus-induced BOLD and CBF changes were 3.4 +/- 1.6% and 98 +/- 33%, respectively. The T1 synaptic activity maps extended along the cortex, whereas the hemodynamic-based activation maps extended radially along the vessels. Spatial overlaps among the synaptic activity, BOLD, and CBF activation maps showed excellent co-registrations. The center-of-mass offsets between any two activation maps were less than 200 microm, suggesting that hemodynamic-based fMRI techniques (at least at high field) can be used to accurately map the spatial loci of synaptic activity.
Keywords
electrical activity; forepaw somatosensory stimulation; cerebral blood flow; hemodynamic response
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