title: Weak language lateralization affects both verbal and spatial skills: an fMRI study in 297 subjects.
abstract: The present study reappraised the relationship between hemispheric specialization strength and cognitive skills in a sample of 297 individuals including 153 left-handers. It additionally assessed the interaction with manual laterality factors, such as handedness, asymmetry of hand motor skills, and familial sinistrality. A Hemispheric Functional Lateralization Index (HFLI) for language was derived from fMRI. Through mixture Gaussian modeling, three types of language hemispheric lateralization were defined: typical (left hemisphere dominance with clear positive HFLI), ambilateral (no dominant hemisphere with HFLI values close to 0), and strongly-atypical (right-hemisphere dominance with clear negative HFLI values). Three cognitive scores were derived from 12 tests covering various aspects of verbal and spatial cognition. Compared to both typical and strongly-atypical participants, those ambilateral for language production had lower performances in verbal and non-verbal domains, indicating that hemispheric specialization and cognitive skills are related in adults. Furthermore, this relationship was independent from handedness and asymmetry for motor skills, as no interaction was observed between these factors. On the other hand, the relationship between familial sinistrality and cognitive skills tended to differ according to language lateralization type. In contrast to previous reports in children, in the present adult population, we found no linear correlation between HFLI and cognitive skills, regardless of lateralization type.
authors.affiliation: Université de Bordeaux, GIN, UMR 5296, F-33000 Bordeaux, France; CNRS, GIN, UMR 5296, F-33000 Bordeaux, France; CEA, GIN, UMR 5296, F-33000 Bordeaux, France. Electronic address: emmanuel.mellet@u-bordeaux.fr.
authors.forename: E
authors.initials: E
authors.lastname: Mellet
authors.affiliation: Université de Bordeaux, GIN, UMR 5296, F-33000 Bordeaux, France; CNRS, GIN, UMR 5296, F-33000 Bordeaux, France; CEA, GIN, UMR 5296, F-33000 Bordeaux, France.
authors.forename: L
authors.initials: L
authors.lastname: Zago
authors.affiliation: Université de Bordeaux, GIN, UMR 5296, F-33000 Bordeaux, France; CNRS, GIN, UMR 5296, F-33000 Bordeaux, France; CEA, GIN, UMR 5296, F-33000 Bordeaux, France.
authors.forename: G
authors.initials: G
authors.lastname: Jobard
authors.affiliation: Université de Bordeaux, GIN, UMR 5296, F-33000 Bordeaux, France; CNRS, GIN, UMR 5296, F-33000 Bordeaux, France; CEA, GIN, UMR 5296, F-33000 Bordeaux, France.
authors.forename: F
authors.initials: F
authors.lastname: Crivello
authors.affiliation: Université de Bordeaux, GIN, UMR 5296, F-33000 Bordeaux, France; CNRS, GIN, UMR 5296, F-33000 Bordeaux, France; CEA, GIN, UMR 5296, F-33000 Bordeaux, France.
authors.forename: L
authors.initials: L
authors.lastname: Petit
authors.affiliation: Université de Bordeaux, GIN, UMR 5296, F-33000 Bordeaux, France; CNRS, GIN, UMR 5296, F-33000 Bordeaux, France; CEA, GIN, UMR 5296, F-33000 Bordeaux, France.
authors.forename: M
authors.initials: M
authors.lastname: Joliot
authors.affiliation: Université de Bordeaux, GIN, UMR 5296, F-33000 Bordeaux, France; CNRS, GIN, UMR 5296, F-33000 Bordeaux, France; CEA, GIN, UMR 5296, F-33000 Bordeaux, France.
authors.forename: B
authors.initials: B
authors.lastname: Mazoyer
authors.affiliation: Université de Bordeaux, GIN, UMR 5296, F-33000 Bordeaux, France; CNRS, GIN, UMR 5296, F-33000 Bordeaux, France; CEA, GIN, UMR 5296, F-33000 Bordeaux, France.
authors.forename: N
authors.initials: N
authors.lastname: Tzourio-Mazoyer
mesh_terms: D000328:Adult; D005260:Female; D007839:Functional Laterality / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D009048:Motor Skills / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D055815:Young Adult
keywords: Cognitive skills; Familial sinistrality; Handedness; Hemispheric specialization