Variability of fMRI activation during a phonological and semantic language task in healthy subjects

Mohamed L. Seghier, François Lazeyras, Alan J. Pegna, Jean Marie Annoni, Ivan Zimine, Eugène Mayer, Christoph M. Michel, Asaid Khateb

Research output: Contribution to journalArticlepeer-review


Assessing inter-individual variability of functional activations is of practical importance in the use of functional magnetic resonance imaging (fMRI) in a clinical context. In this fMRI study we addressed this issue in 30 right-handed, healthy subjects using rhyme detection (phonologic) and semantic categorization tasks. Significant activations, found mainly in the left hemisphere, concerned the inferior frontal gyrus, the superior/middle temporal gyri, the prefrontal cortex, the inferior parietal lobe, the superior parietal lobule/superior occipital gyrus, the pre-central gyrus, and the supplementary motor area. Intensity/spatial analysis comparing activations in both tasks revealed an increased involvement of frontal regions in the semantic task and of temporo-parietal regions in the phonologic task. The frequency of activation analyzed in nine regional subdivisions revealed a high inter-subject variability but showed that the most frequently activated regions were the inferior frontal gyrus and the prefrontal cortex. Laterality indices, strongly lateralizing in both tasks, were slightly higher in the semantic (0.76 ± 0.19) than the phonologic task (0.66 ± 0.27). Frontal dominance indices (a measure of frontal vs. posterior left hemisphere dominance) indicated more robust frontal activations in the semantic than the phonologic task. Our study allowed the characterization of the most frequently involved foci in two language tasks and showed that the combination of these tasks constitutes a suitable tool for determining language lateralization and for mapping major language areas.

Original languageEnglish
Pages (from-to)140-155
Number of pages16
JournalHuman Brain Mapping
Issue number3
StatePublished - Nov 2004
Externally publishedYes


  • Functional magnetic resonance imaging
  • Left hemisphere lateralization
  • Rhyme detection
  • Semantic categorization

ASJC Scopus subject areas

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


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