Neurophysiological investigation of the basis of the fMRI signal

Functional magnetic resonance imaging (fMRI) is widely used to study the operational organization of the human brain, but the exact relationship between the measured fMRI signal and the underlying neural activity is unclear. Here we present simultaneous intracortical recordings of neural signals and...

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Bibliographic Details
Published in:Nature (London) 2001-07, Vol.412 (6843), p.150-157
Main Authors: Logothetis, Nikos K, Pauls, Jon, Augath, Mark, Trinath, Torsten, Oeltermann, Axel
Format: Article
Language:English
Subjects:
Action Potentials
Analysis
Animals
Biological and medical sciences
Brain
Contrast Sensitivity
Electric properties
Electrodes
Electrophysiology
Fundamental and applied biological sciences. Psychology
General aspects. Models. Methods
Hemodynamics
Humanities and Social Sciences
Macaca mulatta
Magnetic Resonance Imaging
Methods
Monkeys & apes
multidisciplinary
Neurology
Neurons
Neurons - physiology
Neurophysiology
neurovascular system
NMR
Nuclear magnetic resonance
Oxygen
Oxygen - blood
Photic Stimulation
Science
Signal Processing, Computer-Assisted
Synaptic Transmission
Systems analysis
Vertebrates: nervous system and sense organs
Visual Cortex - physiology
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Summary:Functional magnetic resonance imaging (fMRI) is widely used to study the operational organization of the human brain, but the exact relationship between the measured fMRI signal and the underlying neural activity is unclear. Here we present simultaneous intracortical recordings of neural signals and fMRI responses. We compared local field potentials (LFPs), single- and multi-unit spiking activity with highly spatio-temporally resolved blood-oxygen-level-dependent (BOLD) fMRI responses from the visual cortex of monkeys. The largest magnitude changes were observed in LFPs, which at recording sites characterized by transient responses were the only signal that significantly correlated with the haemodynamic response. Linear systems analysis on a trial-by-trial basis showed that the impulse response of the neurovascular system is both animal- and site-specific, and that LFPs yield a better estimate of BOLD responses than the multi-unit responses. These findings suggest that the BOLD contrast mechanism reflects the input and intracortical processing of a given area rather than its spiking output.
ISSN:0028-0836
1476-4687
DOI:10.1038/35084005