Title: Pittsburgh Talk
1Functional Magnetic Resonance Imaging and
Intrinsic Optical Imaging Signals Spatial
specificity to neuronally active site
Seong-Gi Kim
Brain Imaging Research Center, University of
Pittsburgh
Supported by NIH, McKnight Fdn, Keck Fdn
2Collaborators
Tim Duong Dae-Shik Kim Noam Harel Fuqiang
Zhao Sang-Pil Lee Ping Wang Tsukasa Nagaoka Eric
Cohen Hiro Fukuda
Costantino Iadecola Kamil Ugurbil Manabu
Tanifuji Bill Eddy
3Functional Brain Mapping ( gta few millimeters)
4Functional Brain Mapping (sub-millimeter)
3x3x3 mm3
Can we resolve cortical laminar and columnar
activity?
5Orientation Columns of Cat Visual Cortex (Area 18)
2-DG map
5 mm
(Lowel Singer, 1990)
6Spatial Specificity
- fMRI Responses
- Perfusion - CBF, CBV
- BOLD (dHb) Conventional gradient-echo and
spin-echo
- Intrinsic Optical Imaging Signals
7Conventional dHb-based (BOLD) fMRI of Cat Visual
Cortex
Cross Correlation Value
Midline (sagittal sinus)
1 mm
4.7T, GE BOLD
8Vascular structures in the striate cortex
Intracortical veins 80 120 ?m diameter 1 2
mm apart
From Duvernoy, HM. The Human Brain, Surface,
Three-dimensional Sectional Anatomy with MRI, and
Blood Supply. Springer-Verlag, 1999.
9To improve spatial specificity, signals from
large vessels should be minimized.
Is stimulation-induced perfusion response
widespread and diffused?
10Arterial Spin Labeling Perfusion fMRI
1 mm
0.8
CC
0.3
Midline (sagittal sinus)
FAIR w/ Single-Shot EPI 4.7 Tesla
Duong et al. PNAS, 2001
11 45o
135o
1 mm
Duong et al. PNAS, 2001
12CBF response is specific to cortical columns. How
about CBV?
Plasma CBV can be measured using MRI after
injection of contrast agent iron oxides.
13Spatial Specificity
- fMRI Responses
- Perfusion - CBF, CBV
- BOLD Conventional gradient-echo and spin-echo
- Intrinsic Optical Imaging Signals
14Orientation Columns obtained dHb-weighted Optical
Imaging
Vessels
1 mm
Columns
620 nm wavelength, differential image
15Spatiodynamics of dHb-weighted optical imaging
signals during single orientation stimulation
Anatomy
-1.0
0.0
0.5
1.0
1.5
2.0
3.0
3.5
4.0
4.5
5.0
5.5
Initial dip high spatial specificity lt- increase
in CMRO2 Later positive change poor spatial
specificity lt- increase in CBF
(Malonek Grinvald, Science, 1996)
16Column-specific dHb signal is relatively small,
regardless of positive or negative signal, when
neural activity-induced dHbs drain into
non-specific large veins. Only early portion
of the dip (before draining into large vessels)
is specific to a sub-millimeter resolution.
17Cerebral blood flow and volume control _at_
microvessels
Capillary/tissue-specific hemodynamic mapping
techniques can image sub-millimeter columnar and
laminar functional structures.
18Thank You