title: Strengthening of laterality of verbal and visuospatial functions during childhood and adolescence.
abstract: Cognitive functions in the child's brain develop in the context of complex adaptive processes, determined by genetic and environmental factors. Little is known about the cerebral representation of cognitive functions during development. In particular, knowledge about the development of right hemispheric (RH) functions is scarce. Considering the dynamics of brain development, localization and lateralization of cognitive functions must be expected to change with age. Twenty healthy subjects (8.6-20.5 years) were examined with fMRI and neuropsychological tests. All participants completed two fMRI tasks known to activate left hemispheric (LH) regions (language tasks) and two tasks known to involve predominantly RH areas (visual search tasks). A laterality index (LI) was computed to determine the asymmetry of activation. Group analysis revealed unilateral activation of the LH language circuitry during language tasks while visual search tasks induced a more widespread RH activation pattern in frontal, superior temporal, and occipital areas. Laterality of language increased between the ages of 8-20 in frontal (r = 0.392, P = 0.049) and temporal (r = 0.387, P = 0.051) areas. The asymmetry of visual search functions increased in frontal (r = -0.525, P = 0.009) and parietal (r = -0.439, P = 0.027) regions. A positive correlation was found between Verbal-IQ and the LI during a language task (r = 0.585, P = 0.028), while visuospatial skills correlated with LIs of visual search (r = -0.621, P = 0.018). To summarize, cognitive development is accompanied by changes in the functional representation of neuronal circuitries, with a strengthening of lateralization not only for LH but also for RH functions. Our data show that age and performance, independently, account for the increases of laterality with age.
authors.affiliation: Paediatric Neurology, Inselspital Children's University Hospital, University Bern, Bern, Switzerland.
authors.forename: Regula
authors.initials: R
authors.lastname: Everts
authors.forename: Karen
authors.initials: K
authors.lastname: Lidzba
authors.forename: Marko
authors.initials: M
authors.lastname: Wilke
authors.forename: Claus
authors.initials: C
authors.lastname: Kiefer
authors.forename: Michela
authors.initials: M
authors.lastname: Mordasini
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schroth
authors.forename: Walter
authors.initials: W
authors.lastname: Perrig
authors.forename: Maja
authors.initials: M
authors.lastname: Steinlin
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000254:growth & development*; D001931:Brain Mapping; D002648:Child; D003071:Cognition / Q000502:physiology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology; D014705:Verbal Behavior / Q000502:physiology*; D055815:Young Adult