Paper Info
Title
Analysis of oxygen metabolism implies a neural origin for the negative BOLD response in human visual cortex
Abstract
The sustained negative blood oxygenation level-dependent (BOLD) response in functional MRI is observed universally, but its interpretation is controversial. The origin of the negative response is of fundamental importance because it could provide a measurement of neural deactivation. However, a substantial component of the negative response may be due to a non-neural hemodynamic artifact. To distinguish these possibilities, we have measured evoked BOLD, cerebral blood flow (CBF), and oxygen metabolism responses to a fixed visual stimulus from two different baseline conditions. One is a normal resting baseline, and the other is a lower baseline induced by a sustained negative response. For both baseline conditions, CBF and oxygen metabolism responses reach the same peak amplitude. Consequently, evoked responses from the negative baseline are larger than those from the resting baseline. The larger metabolic response from negative baseline presumably reflects a greater neural response that is required to reach the same peak amplitude as that from resting baseline. Furthermore, the ratio of CBF to oxygen metabolism remains approximately the same from both baseline states (∼2:1). This tight coupling between hemodynamic and metabolic components implies that the magnitude of any hemodynamic artifact is inconsequential. We conclude that the negative response is a functionally significant index of neural deactivation in early visual cortex.
Year
DOI
Venue
2007
10.1016/j.neuroimage.2006.09.015
NeuroImage
Field
DocType
Volume
Hemodynamics,Brain mapping,Neuroscience,Visual cortex,Neural Inhibition,Psychology,Oxygenation,Cerebral blood flow,Stimulus (physiology),Magnetic resonance imaging
Journal
36
Issue
ISSN
Citations 
2
1053-8119
27
PageRank 
References 
Authors
2.03
7
3
Name
Order
Citations
PageRank
Brian N. Pasley1272.03
Ben A. Inglis2272.03
Ralph Freeman3272.37