[CBIAnnounce] REMINDER: MRI Users Group Meeting Presentation, Friday, February 20th at 4pm

Leela Nathan ln19 at nyu.edu
Wed Feb 18 11:44:40 EST 2004


Please join us in Room 815, Meyer on Friday, February 20th at 4:00PM for the
following presentation:

 

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High field BOLD fMRI: strengths and limitations for the visual
neuroscientist 

 

Presented by: Cheryl Olman, Post-doctoral fellow, Center for Magnetic
Resonance Research, University of Minnesota

 

For BOLD-based fMRI to provide useful information about neural function, the
BOLD signal must be directly related to underlying changes in neural
activity. A linear relationship between BOLD signal changes and cortical
activity averaged over large regions of cortex (> 1 square centimeter) is
commonly accepted. Does the spatial averaging inherent in the 

hemodynamic response impose a lower limit on the spatial scale at which we
can quantitatively link the BOLD response with neural activity? I will
describe several experiments investigating the spatial relationship between
visually evoked neural activity and the V1 BOLD response. Even at high field
(7T), the gradient echo BOLD signal is limited in spatial resolution,
although there is evidence for two components in this signal (from large and
small vessels), as well as the expected advantage of spin echo BOLD fMRI for
studies that require high spatial resolution. I have also been using Gabor
patches of different sizes, randomly distributed at different densities to
study the independent roles of spatial frequency and image feature density
in determining the magnitude of spatially distributed neural activity and
the resulting local (~ 1 square millimeter) and global (> 1 square
centimeter) V1 responses. These results, and the underlying model of V1
neural responses, make some interesting comments about the pitfalls of
studying only regionally averaged BOLD responses to complicated or
heterogeneous images.

 

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Refreshments will be served.

 

Leela Nathan-Waka

Administrative Coordinator

Center for Brain Imaging

6 Washington Place, 1st Fl.

New York, NY 10003

PH: 212-992-8749

FX: 212-995-4570

 

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