A method to determine activation thresholds in fMRI paradigms

Stephan Arndt, Sherri Gold, Ted Cizadlo, Jie Zheng, James C. Ehrhardt, Michael Flaum

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Determining meaningful activation thresholds in functional magnetic resonance imaging (fMRI) paradigms is complicated by several factors. These include the time-series nature of the data, the influence of physiological rhythms (e.g. respiration) and vacillations introduced by the experimental design (e.g. cueing). We present an empirical threshold for each subject and each fMRI experiment that takes these factors into account. The method requires an additional fMRI data set as similar to the experimental paradigm as possible without dichotomously varying the experimental task of interest. A letter fluency task was used to illustrate this method. This technique differs from classical methods since the Pearson correlation probability values tabulated from statistical theory are not used. Rather, each subject defines his or her own set of threshold probability values for correlations. It is against these empirical thresholds, not Pearson's, that an experimental fMRI correlation is assessed.

Original languageEnglish
Pages (from-to)15-22
Number of pages8
JournalPsychiatry Research - Neuroimaging
Volume75
Issue number1
DOIs
StatePublished - Aug 8 1997
Externally publishedYes

Keywords

  • Brain imaging
  • Image analysis
  • Statistical methods

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