[Does the individual adaptation of standardized speech paradigmas for clinical functional magnetic resonance imaging (fMRI) effect the localization of the language-dominant hemisphere and of Broca's and Wernicke's areas].
OBJECTIVE
Functional magnetic resonance imaging (fMRI) localizes Broca's area (B) and Wernicke's area (W) and the hemisphere dominant for language. In clinical fMRI, adapting the stimulation paradigms to each patient's individual cognitive capacity is crucial for diagnostic success. To interpret clinical fMRI findings correctly, we studied the effect of varying frequency and number of stimuli on functional localization, determination of language dominance and BOLD signals.


METHODS
Ten volunteers (VP) were investigated at 1.5 Tesla during visually triggered sentence generation using a standardized block design. In four different measurements, the stimuli were presented to each VP with frequencies of 1/1 s, (1/2) s, (1/3) s and (1/6) s.


RESULTS
The functional localizations and the correlations of the measured BOLD signals to the applied hemodynamic reference function (r) were almost independent from frequency and number of the stimuli in both hemispheres, whereas the relative BOLD signal changes (DeltaS) in B and W increased with the stimulation rate, which also changed the lateralization indices. The strongest BOLD activations were achieved with the highest stimulation rate or with the maximum language production task, respectively.


CONCLUSIONS
The adaptation of language paradigms necessary in clinical fMRI does not alter the functional localizations but changes the BOLD signals and language lateralization which should not be attributed to the underlying brain pathology.
Konrad
F
F
Abteilung Neuroradiologie, Neurologische Klinik, Universitätsklinikum Heidelberg.
Nennig
E
E
Ochmann
H
H
Kress
B
B
Sartor
K
K
Stippich
C
C
D000328:Adult; D001931:Brain Mapping; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D007839:Functional Laterality; D006439:Hemodynamics; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D013702:Temporal Lobe / Q000502:physiology*; D013997:Time Factors