Neuroscience 2005 Abstract
| Presentation Number: | 582.1 |
|---|---|
| Abstract Title: | Confirmation of iso-orientation maps in cat visual cortex revealed by functional MRI with optical imaging of intrinsic signals. |
| Authors: |
Fukuda, H.*1
; Moon, C.1
; Kim, S.1
1Dept. Neurobiol., Univ. of Pittsburgh, Pittsburgh, PA |
| Primary Theme and Topics |
Sensory and Motor Systems - Vision -- Visual cortex: Functional organization and circuitry |
| Session: |
582. Visual Cortex: Topography II Slide |
| Presentation Time: | Tuesday, November 15, 2005 8:00 AM-8:15 AM |
| Location: | Washington Convention Center - Room 144A |
| Keywords: | BLOOD VOLUME, ORIENTATION COLUMNS |
[Aim] Recent studies using functional magnetic resonance imaging (fMRI) have demonstrated the capability of mapping submillimeter-scale functional structures. However, the functional maps have not been evaluated by other conventional techniques. The purpose of this study was to compare iso-orientation maps obtained from fMRI to those with optical intrinsic signal (OIS) imaging in the same recording area.
[Methods] Orientation specific activation was measured with cerebral blood volume (CBV)-weighted fMRI and OIS imaging sequentially from the same anesthetized cat. An identical periodic visual stimulation (continuous full-field moving gratings of 8 orientations (10 s each) / period) was used in both measurements. CBV-weighted fMRI was performed at 9.4 Tesla with monocrystalline iron oxide nanoparticle (10 mg/kg MION) on a 2 x 2-cm area parallel to the marginal gyrus of one hemisphere. An imaging slice (128 x 128 pixels, 1 mm thickness) was positioned ~500 µm below the pial mater. The position of the imaging slice was determined based on cortical emerging veins with a three-dimensional venogram. A pial vascular pattern above the imaging slice was also obtained at higher resolution (256 x 256 pixels). After MRI experiments 570-nm OIS imaging was performed on the same imaging area as the fMRI. A frequency component at the stimulation cycle (80-s period) was extracted from the CBV signal to obtain iso-orientation maps. Based on pial vessel patterns the iso-orientation maps with fMRI and OIS were aligned manually.
[Results] Iso-orientation patches were only detected at the specific stimulation cycle (1/80 Hz). Although we were not able to achieve a perfect pial vessel alignment, the fMRI iso-orientation patches were well co-localized to the OIS patches. This suggests that the CBV-weighted fMRI with columnar resolution can be applied to brain regions without depth limitations.
[Acknowledgements] We thank Sung-Hong Park for MR venography and Michelle Tasker for animal preparation.
[Methods] Orientation specific activation was measured with cerebral blood volume (CBV)-weighted fMRI and OIS imaging sequentially from the same anesthetized cat. An identical periodic visual stimulation (continuous full-field moving gratings of 8 orientations (10 s each) / period) was used in both measurements. CBV-weighted fMRI was performed at 9.4 Tesla with monocrystalline iron oxide nanoparticle (10 mg/kg MION) on a 2 x 2-cm area parallel to the marginal gyrus of one hemisphere. An imaging slice (128 x 128 pixels, 1 mm thickness) was positioned ~500 µm below the pial mater. The position of the imaging slice was determined based on cortical emerging veins with a three-dimensional venogram. A pial vascular pattern above the imaging slice was also obtained at higher resolution (256 x 256 pixels). After MRI experiments 570-nm OIS imaging was performed on the same imaging area as the fMRI. A frequency component at the stimulation cycle (80-s period) was extracted from the CBV signal to obtain iso-orientation maps. Based on pial vessel patterns the iso-orientation maps with fMRI and OIS were aligned manually.
[Results] Iso-orientation patches were only detected at the specific stimulation cycle (1/80 Hz). Although we were not able to achieve a perfect pial vessel alignment, the fMRI iso-orientation patches were well co-localized to the OIS patches. This suggests that the CBV-weighted fMRI with columnar resolution can be applied to brain regions without depth limitations.
[Acknowledgements] We thank Sung-Hong Park for MR venography and Michelle Tasker for animal preparation.
Supported by McKnight Foundation, NIH NS44589 & EB003324
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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