Language and spatial attention can lateralize to the same hemisphere in healthy humans.
BACKGROUND
Disorders of language classically occur after left brain lesions, and disorders of spatial attention after right brain lesions. It is unclear whether the hemispheric dissociation of functions is a fixed pattern of brain organization.


OBJECTIVE
The authors determined whether lateralization of language and lateralization of spatial attention also dissociate in people with atypical (i.e., right hemispheric) language dominance.


METHODS
The authors selected 10 subjects with typical, i.e., left hemispheric, and 10 with atypical, i.e., right hemispheric, language representation on a random basis from a sample of 326 healthy volunteers examined with functional transcranial Doppler sonography (fTCD) for language dominance. In these subjects, hemispheric lateralization of cerebral perfusion during a line bisection task was determined with fTCD.


RESULTS
The authors found a dissociation between dominance for language and spatial attention in all but four subjects. In the latter subjects, there was a significant lateralization to the right hemisphere for both tasks. The four subjects showed normal intellectual, linguistic, and spatial performance, with normal EEG and MRI scans of the brain.


CONCLUSIONS
Even in the absence of brain pathology, the same hemisphere can be dominant in control of both language and spatial attention.
Flöel
A
A
Department of Neurology, University of Münster, Germany. floeel@uni-muenster.de
Knecht
S
S
Lohmann
H
H
Deppe
M
M
Sommer
J
J
Dräger
B
B
Ringelstein
E B
EB
Henningsen
H
H
D000328:Adult; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000098:blood supply / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D009949:Orientation / Q000502:physiology*; D011932:Reading; D012016:Reference Values; D012660:Semantics; D017585:Ultrasonography, Doppler, Transcranial; D014705:Verbal Behavior / Q000502:physiology*