Document Detail


Nonlinearities in rapid event-related fMRI explained by stimulus scaling.
MedLine Citation:
PMID:  17113788     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Because of well-known nonlinearities in fMRI, responses measured with rapid event-related designs are smaller than responses measured with spaced designs. Surprisingly, no study to date has tested whether rapid designs also change the pattern of responses across different stimulus conditions. Here we report the results of such a test. We measured cortical responses to a flickering checkerboard at different contrasts using rapid and spaced event-related fMRI. The relative magnitude of responses across contrast conditions differed between rapid and spaced designs. Modeling the effect of the rapid design as a scaling of stimulus strength provided a good account of the data. The data were less well fit by a model that scaled the strength of responses. A similar stimulus scaling model has explained effects of neural adaptation, which suggests that adaptation may account for the observed difference between rapid and spaced designs. In a second experiment, we changed the stimulus in ways known to reduce neural adaptation and found much smaller differences between the two designs. Stimulus scaling provides a simple way to account for nonlinearities in event-related fMRI and relate data from rapid designs to data gathered using slower presentation rates.
Authors:
Genevieve M Heckman; Seth E Bouvier; Valerie A Carr; Erin M Harley; Kristen S Cardinal; Stephen A Engel
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2006-11-17
Journal Detail:
Title:  NeuroImage     Volume:  34     ISSN:  1053-8119     ISO Abbreviation:  Neuroimage     Publication Date:  2007 Jan 
Date Detail:
Created Date:  2006-12-04     Completed Date:  2007-02-13     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  9215515     Medline TA:  Neuroimage     Country:  United States    
Other Details:
Languages:  eng     Pagination:  651-60     Citation Subset:  IM    
Affiliation:
UCLA Department of Psychology, Franz Hall 1282a, Los Angeles, CA 90095, USA.
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological
Adult
Brain / physiology*
Female
Humans
Magnetic Resonance Imaging / methods*
Male
Models, Neurological*
Photic Stimulation
Grant Support
ID/Acronym/Agency:
EY11862/EY/NEI NIH HHS; MH015795/MH/NIMH NIH HHS; R01 EY011862-05/EY/NEI NIH HHS; RR00865/RR/NCRR NIH HHS; RR12169/RR/NCRR NIH HHS; RR13642/RR/NCRR NIH HHS
Comments/Corrections

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