Notes
Slide Show
Outline
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Efficient Design of Event-related fMRI Experiments with
M-sequences


Giedrius Buracas
Geoff Boynton
SNL-B, Salk Institute
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Rapid Event-related vs. Block Design
  • ER design is preferred for estimation of Hemodynamic Response (HDR) function, block design is preferred for detection of activation (Liu et al, 2001).


  • Randomized ER design may resolve activation induced by individual cognitive events, that are lumped together during block design experiments.


  • ER design might be necessary for studies that have to minimize habituation and expectation effects and for studies that are addressing these factors.
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ER-fMRI responses
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HDR estimation
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Maximum likelihood estimation
(e.g. Dale, 1999)
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Estimation efficiency
(expected accuracy of HDR estimate)
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Strategies for maximizing HDR estimation efficiency
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Conditions of Maximum
Estimation Efficiency
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Our strategy
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What are m-sequences
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Stochastic vs. m-sequence-governed event vectors
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M-sequence efficiency is hard to reach by random search
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Efficiency of random vs. m-sequences
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m-sequences for overlapping events
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m-sequences for non-overlapping events
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Real data
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Recipe
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 p.s.