Neuroscience 2000 Abstract
| Presentation Number: | 550.2 |
|---|---|
| Abstract Title: | Perfusion-based functional MRI of the cat visual cortex at columnar resolution: comparison with bold spatial specificity. |
| Authors: |
Duong, T. Q.*1
; Kim, D. S.1
; Kim, S. G.1
1Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, MN |
| Primary Theme and Topics |
F. Sensory Systems - 79. Visual cortex: striate |
| Session: |
550. Visual cortex: striate--maps and imaging II Poster |
| Presentation Time: | Tuesday, November 7, 2000 2:00 PM-3:00 PM |
| Location: | Hall G-J |
| Keywords: | Blood Flow, fMRI, BOLD, CBF |
We recently reported the successful use of the early-negative BOLD fMRI signal to map orientation columns in the cat visual cortex. However, the early-negative BOLD response can not be readily used for routine mapping of brain functions because of its low signal-to-noise combined with the need for high spatio-temporal resolution. In this study, we evaluated the feasibility of using perfusion-based fMRI to resolve columnar layouts in the same cat model and compared its spatial specificity with that of the conventional BOLD. The MRI perfusion-based signal is devoid of large draining venous vessels and is derived from a single physiological parameter without the convoluted susceptibility effect present in the BOLD signal. We hypothesized that perfusion-based fMRI is better suited to resolve columnar layouts as it is more spatially localized relative to the conventional BOLD signal. Perfusion-based and BOLD fMRI were performed on 6 cats. The visual stimulus consisted of drifting gratings of 4 orientations (identical but stationary gratings for the control period). Single-shot, echo-planar images at 4.7T were acquired using TR=3s, TE=31ms, TI=1.5s, matrix=64x64, FOV=18x18mm2 (280x280μm2), and 2-mm slice.
The stimulus-induced changes in perfusion were typically 20-30%. Perfusion-based maps were indeed devoid of large draining vessels and more spatially localized than the conventional BOLD maps. Repeated measurements yielded reproducible perfusion-based maps. The patterns of the perfusion-based maps were consistent with well-established columnar layouts. The perfusion-based functional maps of orthogonal orientation stimuli were spatially complementary and their percent changes showed orientation-specific selectivity. The key topological characteristics of the perfusion-based maps were consistent with those obtained in optical imaging studies. These results suggest that hemodynamic-based techniques can be used to localize individual columns if large draining-vessel contributions are eliminated. In contrast to the BOLD technique, perfusion-based fMRI can be readily carried out at low magnetic fields without loss of sensitivity and specificity because it is relatively field independent.
The stimulus-induced changes in perfusion were typically 20-30%. Perfusion-based maps were indeed devoid of large draining vessels and more spatially localized than the conventional BOLD maps. Repeated measurements yielded reproducible perfusion-based maps. The patterns of the perfusion-based maps were consistent with well-established columnar layouts. The perfusion-based functional maps of orthogonal orientation stimuli were spatially complementary and their percent changes showed orientation-specific selectivity. The key topological characteristics of the perfusion-based maps were consistent with those obtained in optical imaging studies. These results suggest that hemodynamic-based techniques can be used to localize individual columns if large draining-vessel contributions are eliminated. In contrast to the BOLD technique, perfusion-based fMRI can be readily carried out at low magnetic fields without loss of sensitivity and specificity because it is relatively field independent.
Supported by NIH (RR08079, NS10930, NS38295, MH60724).
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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