Physiologically evoked neuronal current MRI in a bloodless turtle brain: Detectable or not?

Document Type

Article

Publication Date

2009

Abstract

Contradictory reports regarding the detection of neuronal currents have left the feasibility of neuronal current MRI (ncMRI) an open question. Most previous ncMRI studies in human subjects are suspect due to their inability to separate or eliminate hemodynamic effects. In this study, we used a bloodless turtle brain preparation that eliminates hemodynamic effects, to explore the feasibility of detecting visually-evoked ncMRI signals at 9.4 T. Intact turtle brains, with eyes attached, were dissected from the cranium and placed in artificial cerebral spinal fluid. Light flashes were delivered to the eyes to evoke neuronal activity. Local field potential (LFP) and MRI signals were measured in an interleaved fashion. Robust visually-evoked LFP signals were observed in turtle brains, but no significant signal changes synchronized with neuronal currents were found in the ncMRI images. In this study, detection thresholds of 0.1% and 0.1° were set for MRI magnitude and phase signal changes, respectively. The absence of significant signal changes in the MRI images suggests that visually-evoked ncMRI signals in the turtle brain are below these detectable levels.

Publication Title

NeuroImage

Volume

47

Issue

4

First Page

1268

Last Page

1276

Comments

This article was published in NeuroImage, Volume 47, Issue 4, Pages 1268-1276.

The published version is available at http://dx.doi.org/10.1016/j.neuroimage.2009.06.017.

Copyright © 2009 Elsevier.

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