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Volume effect of localized injection in functional MRI and electrophysiology
Author(s) -
Aksenov Daniil P.,
Li Limin,
Iordanescu Gheorghe,
Miller Michael J.,
Wyrwicz Alice M.
Publication year - 2014
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.24996
Subject(s) - electrophysiology , neuroscience , stimulus (psychology) , magnetic resonance imaging , functional magnetic resonance imaging , resting state fmri , chemistry , medicine , psychology , psychotherapist , radiology
Purpose The local injection of neurotransmitter agonists and antagonists to modulate recorded neurons in awake animals has long been an important and widely used technique in neuroscience. Combined with functional magnetic resonance imaging (fMRI) and simultaneous electrophysiology, local injection enables the study of specific brain regions under precise modulations of their neuronal activity. However, localized injections are often accompanied by mechanical displacement of the tissue, known as volume effect (VE), which can induce changes in electrophysiological recordings as well as artifacts that are particular to fMRI studies. Methods We characterize the changes produced by VE in an agarose phantom as well as during stimulus‐evoked and resting‐state fMRI and simultaneously acquired electrophysiology in awake rabbits. Results Our results demonstrate that localized injection can produce significant intensity changes in fMRI data, even while effects on electrophysiological recordings are minimized. These changes are localized to the vicinity of the injection needle and diminish over time due to diffusion of the injected volume. Conclusion Sufficient time should be allowed for drug diffusion to ensure stable results, particularly for resting‐state fMRI experiments. Magn Reson Med 72:1170–1175, 2014. © 2013 Wiley Periodicals, Inc.