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Regional differences in neurovascular coupling in rat brain as determined by fMRI and electrophysiology

Lookup NU author(s): Professor Andrew BlamireORCiD

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Abstract

Increases in neuronal activity induce local increases in cerebral perfusion However, our understanding of the processes underlying this neurovascular coupling remains Incomplete and, particularly, how these vary across the brain Recent work supports an important role for astrocytes in neurovascular coupling. in large part via activation of their metabotropic glutamate receptors (mGluR). Here, using a combination of functional magnetic resonance imaging (fMRI) and electrophysiology we demonstrate regional heterogeneity in the mechanisms underlying neurovascular coupling Direct electrical stimulation of the rat hindpaw sensorimotor cortex induces blood oxygenation level dependent (BOLD) and cerebral blood volume (CBV) fMRI responses in several anatomically distinct cortical and subcortical structures Following intraperitoneal administration of the type 5 mGluR antagonist, MPEP, both BOLD and CBV responses to cortical stimulation were significantly reduced, whilst the local field potential (LFP) responses remained largely constant. Spatially, the degree of reduction in fMRI responses varied between cortical and subcortical regions (primary cortex similar to 18% vs striatum similar to 66%), and also between primary and secondary cortical areas (similar to 18% vs similar to 55%). Similarly, greater decreases in response amplitude were seen in the contralateral secondary cortex (similar to 91%) and ipsilateral striatum (similar to 70%). compared to the primary cortex (similar to 44%) Following MPEP, a negative component of the BOLD and CBV responses became more apparent, suggesting that different mechanisms mediate vasodilatory and vasoconstrictory responses Interestingly, under baseline conditions the quantitative relationship between fMRI and LFP responses in cortical and subcortical regions was markedly different. Our data indicate that coupling between neuronal and fMRI responses is neither empirically nor mechanistically consistent across the brain. (C) 2010 Elsevier Inc. All rights reserved.

Publication metadata

Author(s): Sloan HL, Austin VC, Blamire AM, Schnupp JWH, Lowe AS, Allers KA, Matthews PM, Sibson NR

Publication type: Article

Publication status: Published

Journal: NeuroImage

Year: 2010

Volume: 53

Issue: 2

Pages: 399-411

Print publication date: 01/11/2010

ISSN (print): 1053-8119

ISSN (electronic): 1095-9572

Publisher: Academic Press

URL: http://dx.doi.org/10.1016/j.neuroimage.2010.07.014

DOI: 10.1016/j.neuroimage.2010.07.014

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