Artikel
Language and its right hemispheric distribution in healthy brains
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Autoren
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Nico Sollmann
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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Bernhard Meyer
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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Florian Ringel
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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Sandro M. Krieg
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| Veröffentlicht: | 13. Mai 2014 |
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Gliederung
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Objective: Repetitive navigated transcranial magnetic stimulation (rTMS) is increasingly used for cortical language mapping. In contrast to direct cortical stimulation (DCS), this technique is also able to provide a map of the distribution of human language in the healthy brain due to ist non-invasive character. Since little is known about the right hemisphere language organization, this technique seems highly feasible for this question.
Method: Fifty healthy and right-handed volunteers underwent cortical language mapping of the right hemisphere by rTMS combined with an object naming task. All errors elicited by rTMS were identified via video analysis and strictly categorized into six different error groups (no response, hesitation, performance error, neologism, semantic error, phonological error). Afterwards, the frequency for each category was calculated and visualized by projecting the results into the cortical parcellation system (CPS). In addition, the individual pain during mapping sessions was measured by using a visual analogue scale (VAS).
Results: Clear language disturbances could be elicited by rTMS of the right hemisphere. Overall, 1,485 naming errors were elicited by 9,839 stimulation trains, which equals an error rate of 15.1%. In females, 5,116 stimulations were performed and 763 language errors of any kind were observed (14.9%). These were mainly located within the mPrG and vPrG. Within males, 4,723 stimulations elicited 722 language errors (15.3%), which were primarily located within middle precentral gyrus (mPrG), ventral precentral gyrus (vPrG), and middle superior temporal gyurs (mSTG).
Conclusions: Even in the non-dominant hemisphere, rTMS is able to cause language impairment, especially hesitation errors. The high rate of errors within mPrG and vPrG has to be regarded as motoric inhibition of speech rather than language. Yet, rTMS within mSTG actually causes impairment of language understanding, which might show us that the right mSTG is also strongly involved in sensory language function.
