Functional anatomy of dominance for speech comprehension in left handers vs right handers
NeuroImage. 1998-07-01; 8(1): 1-16
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1. Neuroimage. 1998 Jul;8(1):1-16.
Functional anatomy of dominance for speech comprehension in left handers vs right
Tzourio N(1), Crivello F, Mellet E, Nkanga-Ngila B, Mazoyer B.
(1)Groupe d’Imagerie Neurofonctionnelle, UPRES EA 2127 Université de Caen and CEA
LRC 13, Caen, France.
In order to study the functional anatomy of hemispheric dominance for language
comprehension we compared the patterns of activations and deactivations with PET
and H(2)15O during a story-listening task in two groups of normal volunteers
selected on the basis of their handedness. The reference task was a silent rest.
The results showed asymmetrical temporal activations favoring the left hemisphere
in right handers (RH) together with Broca’s area and medial frontal activations.
A rightward lateralization of deactivations located in the parietal and inferior
temporal gyrus was also observed. In left handers (LH) the temporal activations
were more symmetrical as were the parietal and inferior frontal deactivations.
Broca’s area and medial frontal gyrus activations were present in LH. The direct
comparison of RH and LH activations revealed larger activations in the left
superior temporal, in particular in the left planum temporale and temporal pole
of RH, while LH activated an additional right middle temporal region. Individual
analysis of LH differences images superimposed on individual MRI planes
demonstrated an important variability of functional dominance, with two LH
leftward lateralized, two symmetrical, and one showing a rightward lateralization
of temporal activations. There was no relationship between functional dominance
and handedness scores. These results are in accordance with data from aphasiology
that suggest a greater participation of the right hemisphere in language
processing in LH. In addition, the presence of bilateral deactivations of the
dorsal route could support the assumption that LH ambilaterality concerns, in
addition to language, other cognitive functions such as visuospatial processing.
PMID: 9698571 [Indexed for MEDLINE]