Neuroscience 2000 Abstract
| Presentation Number: | 309.6 |
|---|---|
| Abstract Title: | Neural correlate of blood oxygenation level dependent functional MRI. |
| Authors: |
Kim, D. S.*1
; Duong, T. Q.1
; Ronen, I.1
; Ugurbil, K.1
; Kim, S. G.1
1Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, |
| Primary Theme and Topics |
F. Sensory Systems - 79. Visual cortex: striate |
| Session: |
309. Visual cortex: striate--maps and imaging I Slide |
| Presentation Time: | Monday, November 6, 2000 2:15 PM-2:30 PM |
| Location: | Room 393 |
| Keywords: | fMRI, Orientation, Neural Correlate, Bold |
Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) has become a pivotal tool in localizing brain functions in vivo. However, despite its wide application in basic and clinical sciences, the electrophysiological basis of the BOLD signals remains elusive. Likewise, the precise spatial congruence between the foci of neuronal and BOLD activity remains controversial. The overall objective of this study is to define the neural correlate of BOLD by performing combined fMRI and single unit recordings in a single subject. We used a 4.7T horizontal bore scanner (Oxford, UK) to label the individual iso-orientation columns in cat primary visual cortex. Animal preparation and stimulation paradigms were similar to those of standard optical imaging experiments. A dense Cartesian grid phantom was placed on the exposed cortex for the fMRI and single-unit signal alignment. Typical MR parameters were: gradient-echo echo-planar images; TE=31ms; TR=0.5 sec; 64×64 or 128×128; FOV=2×2 cm2 (nominal in-plane resolutions of 300×300 or 150×150 μm2/pixel). The BOLD responses were separated into different temporal segments (e.g. early dip vs. late hemodynamic responses) for further comparison with single unit recording data. Following high-resolution fMRI studies, single unit studies were performed on the same animals. Electrodes were inserted into the cortex based on the BOLD functional maps with the guidance from a high-resolution image of the Cartesian grid phantom. The results of our preliminary studies demonstrate that combined measurements of fMRI and single unit responses could indeed be obtained from the same subject. Such a direct validation of BOLD fMRI in an animal system is imperative, as we move towards columnar-resolution BOLD fMRI in humans, where the means of a direct validation are evidently very limited.
Supported by NIH (NS38295, MH60724, MH57180, NS10930, RR08079).
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2000 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2000. Online.
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