Bookheimer S Y, Zeffiro T A, Blaxton T A, Gaillard P W, Theodore W H
Epilepsy Research Branch, NINDS, National Institutes of Health, Bethesda, MD, USA.
Neurology. 2000 Oct 24;55(8):1151-7. doi: 10.1212/wnl.55.8.1151.
To identify automatic speech tasks that reliably demonstrate increased regional cerebral blood flow (rCBF) in Broca's and Wernicke's areas of the cortex using PET.
Localizing language with direct cortical stimulation mapping requires that patients have a stable baseline on tests that engage eloquent cortex. For dysphasic patients or younger children, automatic speech tasks such as counting are often used in lieu of more complex language tests. Evidence from both lesion and neuroimaging studies suggests that these tasks may not adequately engage language cortices. In this study, we examined rCBF during automatic oromotor and speech tasks of varying complexity to identify those eliciting increased CBF in Broca's and Wernicke's areas.
Eight normal volunteers underwent PET during rest, tongue movements, and three automatic speech tasks: repeating a phoneme sequence, repeating the months of the year, and reciting a memorized prose passage. Images were averaged across subjects and compared across tasks for regional localization and laterality.
Whereas all activation tasks produced increased relative CBF in brain regions that correlated with articulation and auditory processing, only the two tasks that used real words (versus phonemes) showed left-lateralized rCBF increases in posterior superior temporal lobe (Wernicke's area), and only the prose repetition task produced left lateralized activity in Broca's area.
Whereas automatic speech typically does not engage language cortex, repeating a memorized prose passage showed unambiguous activation in both Broca's and Wernicke's areas. These results caution against the use of common automatic speech tasks for mapping eloquent cortex and suggest an alternative task for those with poor language abilities or acquired dysphasia who cannot perform standardized language tests reliably.
利用正电子发射断层扫描（PET）识别能可靠显示大脑皮层布洛卡区和韦尼克区局部脑血流量（rCBF）增加的自动言语任务。
通过直接皮层刺激映射来定位语言功能，要求患者在涉及明确皮层的测试中有稳定的基线。对于言语障碍患者或年幼儿童，常使用诸如数数等自动言语任务来替代更复杂的语言测试。来自病变和神经影像学研究的证据表明，这些任务可能无法充分激活语言皮层。在本研究中，我们在不同复杂程度的自动口面部运动和言语任务过程中检测rCBF，以识别那些能引起布洛卡区和韦尼克区脑血流量增加的任务。
8名正常志愿者在静息状态、舌头运动以及三项自动言语任务（重复音素序列、重复一年中的月份、背诵一段记忆的散文段落）期间接受PET检查。对受试者的图像进行平均，并在不同任务间比较区域定位和脑区偏侧化情况。
虽然所有激活任务均使与发音和听觉处理相关的脑区相对脑血流量增加，但只有两项使用真实词汇（而非音素）的任务显示颞上叶后部（韦尼克区）rCBF呈左侧化增加，且只有散文重复任务在布洛卡区产生左侧化激活。
虽然自动言语通常不会激活语言皮层，但背诵一段记忆的散文段落显示在布洛卡区和韦尼克区均有明确激活。这些结果提醒人们不要使用常见的自动言语任务来映射明确皮层，并为那些语言能力差或患有获得性言语障碍而无法可靠完成标准化语言测试的人提出了一种替代任务。
