Comparison of multi-subject ICA methods for analysis of fMRI data

Erik Barry Erhardt, Srinivas Rachakonda, Edward J. Bedrick, Elena A. Allen, Tülay Adali, Vince D. Calhoun

Research output: Contribution to journalArticlepeer-review

559 Scopus citations


Spatial independent component analysis (ICA) applied to functional magnetic resonance imaging (fMRI) data identifies functionally connected networks by estimating spatially independent patterns from their linearly mixed fMRI signals. Several multi-subject ICA approaches estimating subject-specific time courses (TCs) and spatial maps (SMs) have been developed, however, there has not yet been a full comparison of the implications of their use. Here, we provide extensive comparisons of four multi-subject ICA approaches in combination with data reduction methods for simulated and fMRI task data. For multi-subject ICA, the data first undergo reduction at the subject and group levels using principal component analysis (PCA). Comparisons of subject-specific, spatial concatenation, and group data mean subject-level reduction strategies using PCA and probabilistic PCA (PPCA) show that computationally intensive PPCA is equivalent to PCA, and that subject-specific and group data mean subject-level PCA are preferred because of well-estimated TCs and SMs. Second, aggregate independent components are estimated using either noise-free ICA or probabilistic ICA (PICA). Third, subject-specific SMs and TCs are estimated using back-reconstruction. We compare several direct group ICA (GICA) back-reconstruction approaches (GICA1-GICA3) and an indirect back-reconstruction approach, spatio-temporal regression (STR, or dual regression). Results show the earlier group ICA (GICA1) approximates STR, however STR has contradictory assumptions and may show mixed-component artifacts in estimated SMs. Our evidence-based recommendation is to use GICA3, introduced here, with subject-specific PCA and noise-free ICA, providing the most robust and accurate estimated SMs and TCs in addition to offering an intuitive interpretation.

Original languageEnglish (US)
Pages (from-to)2075-2095
Number of pages21
JournalHuman Brain Mapping
Issue number12
StatePublished - Dec 2011
Externally publishedYes


  • Back-reconstruction
  • Brain
  • Dual regression
  • FMRI
  • Functional
  • Group ICA
  • ICA
  • Independent component analysis
  • Spatio-temporal regression

ASJC Scopus subject areas

  • Anatomy
  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Clinical Neurology


Dive into the research topics of 'Comparison of multi-subject ICA methods for analysis of fMRI data'. Together they form a unique fingerprint.

Cite this