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Rezümékötet 2008. - vmtdk

Rezümékötet 2008. - vmtdk

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P L E N Á R I S T U D O M Á N Y O S Ü L É S S Z A K<br />

FUNCTIONAL MAGNETIC REZONANCE – fMRI AND ITS ROLE<br />

IN THE ANALYSIS OF BRAIN LATERALIZATION<br />

Author: Zsuzsanna KALMÁR 6 th year student<br />

Supervisor: Dr. József JANSZKY associate professor<br />

Institution: University of Pécs, Faculty of Medicine, Pécs<br />

Objective: Right-handedness and left-sided speech dominance is an unresolved mystery with unknown cause/effect<br />

relationship. Most studies suggest that the speech lateralization is related to a fundamental brain asymmetry: the<br />

right handedness may be secondary. We analyzed a possibility of an opposite cause/effect relationship: whether asymmetric<br />

hand usage can influence the speech lateralization.<br />

Methods: We determined speech lateralization by functional magnetic resonance imaging in 15 subjects whose<br />

upper limb (UL) had been injured at birth due to unilateral damage of brachial plexus. These subjects were able to<br />

use only one (the non-injured) UL perfectly.<br />

Results: We found that the severity of right-sided UL injury and dysfunction of hand usage correlated with the degree<br />

of left-to-right shift of speech lateralization. There was, however, not a complete switching of speech dominance.<br />

Interpretation: Right-sided UL injury can induce a left-to-right shift in speech lateralization, suggesting that hand<br />

usage can influence the speech dominance. These findings may contradict the broadly accepted theory of that handedness<br />

is a secondary phenomenon due to left-sided hemispheric dominance of speech. However, the cause/effect<br />

problem between asymmetric hand usage and speech dominance is not resolved in this study. Our findings may support<br />

the theory that gestures had a crucial role in human language evolution and is a part of the language system<br />

even today.<br />

Keywords: handedness, functional MRI, speech lateralization<br />

N Y O S D I Á K K Ö R I K O N F E R E N C I A<br />

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