Archive for 10/11/2009

fMRI Limitations And Criticism

10/11/2009 1 comment

FMRI-scan_sectie_85Fancy images, impressive results, but can we really trust the reports of the majority of the neuroimaging studies out there? Here’s a couple of papers discussing the limitations of fMRI that you can read, if you’re interested in learning more about this method:

1. a great review by Nikos K. Logothetis published in Nature a year ago. Here’s the abstract:

Here I give an overview of the current state of fMRI, and draw on neuroimaging and physiological data to present the current understanding of the haemodynamic signals and the constraints they impose on neuroimaging data interpretation. Functional magnetic resonance imaging (fMRI) is currently the mainstay of neuroimaging in cognitive neuroscience.
Advances in scanner technology, image acquisition protocols, experimental design, and analysis methods promise to push forward fMRI from mere cartography to the true study of brain organization. However, fundamental questions concerning the interpretation of fMRI data abound, as the conclusions drawn often ignore the actual limitations of the methodology.”

2. Professor D. Attwell questions the neural basis of functional brain imaging signals:

“The haemodynamic responses to neural activity that underlie the blood-oxygen-level-dependent (BOLD) signal used in functional magnetic resonance imaging (fMRI) of the brain are often assumed to be driven by energy use, particularly in presynaptic terminals or glia.However, recent work has suggested that most brain energy is used to power postsynaptic currents and action potentials rather than presynaptic or glial activity and, furthermore, that haemodynamic responses are driven by neurotransmitter-related signalling and not directly by the local energy needs of the brain. A firm understanding of the BOLD response will require investigation to be focussed on the neural signalling mechanisms controlling blood flow rather than on the locus of energy use.”

P.S: For an introduction to fMRI, visit fMRI 4 Newbies website.

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