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Activation Patterns of Human Auditory Cortex by Various Sounds: A fMRI Study

以功能性磁振造影研究人類大腦聽覺皮質的活化模式

摘要


背景:顳葉在聽知覺處理上,隨著不同的刺激程度與強度,可在初級與次級聽知覺區域造成不同的活化模式,然而,此一功能性分區與不對稱性仍存有若干的爭議,此研究之目的為以多種音聲刺激來探討大腦聽覺相關皮質活化模式。 方法:以5名健康無聽覺障礙之年輕人為受測者,皆為慣用右手者,而且實驗前皆未接觸過實驗用之音聲刺激。多種音聲刺激分別為純音、寬頻噪音、海浪聲、交響樂、以及言語。兩耳接受聲音刺激之同時,進行高磁場系統(3.0T)功能性核磁共振造影檢查。 結果:根據活化的區域和訊號的變化值,雖然不同受試者之間有些微差異存在,不過,不同音聲刺激可得到特異的活化模式:純音活化範圍最小,只在兩側Heschl氏迴顯影,右側明顯大於左側。寬頻噪音與海浪聲音刺激,可得較廣之活化區域,其中,海浪聲音還可活化右側Heschl氏迴附近的上顳迴,以及左側Heschl氏迴後側的上顳迴區域。交響樂可高度活化右側整個上顳迴區與額下迴上區(pars opercularis),而左側強度較弱,主要在Heschl氏迴與前後側的上顳迴區域,還有額下迴上區。言語刺激部分,兩側的Heschl氏迴、上顳迴整區、上顳溝,甚至中顳迴皆被活化,不過左側略大於右側,此外,活化區域還會延伸至左側額下迴上區與上顳迴後區。 結論:非言語刺激主要活化右側大腦半球之聽覺相關皮質,而言語刺激主要活化左側。本研究結果支持上顳迴的前後側為分析複雜音聲刺激的特定區域。

並列摘要


BACKGROUND: Auditory processing by the temporal lobes may involve a functional segregation. However, debate continues concerning the functional asymmetry of auditory processing in humans under different stimulation conditions. The purpose of this study was to elucidate activation patterns of the human brain auditory associated cortices elicited by a serial of sounds. METHODS: Five healthy subjects with normal hearing participated. Five pre-recorded sound tracks were used: a pure tone, a wide-band white noise, sounds of ocean waves, part of Antonio Vivaldi's ”The Four Seasons” concerto No. 1 and a spoken, continuous discourse. Functional magnetic resonance imaging was performed while different sounds were presented binaurally. RESULTS: Characteristic activation patterns were elicited although variability was presented between subjects. Pure tone led to the weakest activation of Heschl's gyrus (HG), bilaterally, mainly on the right. Compared to pure tone, HG activation by white noise and ocean wave sounds was more intense. Ocean wave sounds activated the right superior temporal gyrus (STG) surrounding HG, and the left STG posterior to HG. Classical music activated the entire right superior temporal lobe and the pars opercularis of the inferior frontal gyrus (POIFG). The left HG, anterior and posterior parts of the STG, and the POIFG were weakly activated. Speech activated the entire STG, superior temporal sulcus, and middle temporal gyrus bilaterally, but slightly on the left, with extension toward the left inferior frontal gyrus and planum temporale. CONCLUSIONS: A lateralization for activation of the right by non-speech sounds and the left by speech was detected. Our results support the hypothesis that the anterior and posterior parts of the STG are responsible for complex sound analysis.

並列關鍵字

auditory perception brain mapping fMRI humans

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