Neuroscience 2002 Abstract
Presentation Number: | 325.10 |
---|---|
Abstract Title: | Neural correlate of functional MRI at columnar resolution. |
Authors: |
Toth, L. J.*1,2
; Ronen, I.2
; Ugurbil, K.2
; Kim, D. S.2
1Anat. & Neurobiol., Boston Univ. Sch. of Med., Boston, MA 2Ctr. Magnetic Resonance Rsrch., Univ. Minnesota Med. Sch., Minneapolis, MN |
Primary Theme and Topics |
Sensory Systems - Vision -- Striate visual cortex: Functional organization and circuitry |
Session: |
325. Visual cortex: functional organization Slide |
Presentation Time: | Monday, November 4, 2002 3:15 PM-3:30 PM |
Location: | Room 307A |
Keywords: | cerebral blood flow, BOLD, orientation column, single-unit |
Previously we demonstrated that the +BOLD signal is not sufficiently localized to view structures such as orientation domains in visual cortex. We now asked whether signals based on cerebral blood flow (CBF) could provide better spatial resolution. In the anesthetized cat, we measured CBF and neuronal responses subsequently at corresponding sites from the same animal. Visual stimuli consisted of high-contrast square-wave moving gratings of four orientations, 0.15 cyc/deg, 2Hz. MR parameters were: 4.7T / 31cm, 15-G/cm, 64x64 matrix; single-shot EPI, 2x2cm FOV, 2 mm thickness, TE/TR = 31ms / 0.5s.
Before MRI, the visual cortex was exposed (area 18, AP3=center). A MR-transparent grid and surface RF coil were mounted on the skull. Grid holes were filled with MR-opaque agar, and imaged for precise registration of recording sites with CBF maps. Single-unit responses were obtained for 20 cells in 2 hemispheres.
The power spectrum of single-orientation CBF maps showed a peak at 973 microns (as expected for orientation domains) selectively over area 18. Maps to orthogonal frequencies were spatially opponent. Orientation preference at each pixel was calculated from raw, normalized CBF maps. We observed a good correlation between orientation preference predicted from CBF and the measured orientation preference of single-units. These results suggest that we were able to successfully image orientation domains using CBF. We suggest that our CBF resolution is only limited by the image acquisition resolution of our magnet.
Before MRI, the visual cortex was exposed (area 18, AP3=center). A MR-transparent grid and surface RF coil were mounted on the skull. Grid holes were filled with MR-opaque agar, and imaged for precise registration of recording sites with CBF maps. Single-unit responses were obtained for 20 cells in 2 hemispheres.
The power spectrum of single-orientation CBF maps showed a peak at 973 microns (as expected for orientation domains) selectively over area 18. Maps to orthogonal frequencies were spatially opponent. Orientation preference at each pixel was calculated from raw, normalized CBF maps. We observed a good correlation between orientation preference predicted from CBF and the measured orientation preference of single-units. These results suggest that we were able to successfully image orientation domains using CBF. We suggest that our CBF resolution is only limited by the image acquisition resolution of our magnet.
Supported by NIH (RR08079), The Keck Foundation, The Whitaker Foundation, and NARSAD
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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