Wiesmann M, Kopietz R, Albrecht J, Linn J, Reime U, Kara E, Pollatos O, Sakar V, Anzinger A, Fesl G, Brückmann H, Kobal G, Stephan T
Department of Neuroradiology, Ludwig Maximilian University Munich, Marchioninistrasse 15, 81377 Munich, Germany.
Neuroimage. 2006 Aug 1;32(1):293-300. doi: 10.1016/j.neuroimage.2006.03.022. Epub 2006 May 2.
In two previous fMRI studies, it was reported that eyes-open and eyes-closed conditions in darkness had differential effects on brain activity, and typical patterns of cortical activity were identified. Without external stimulation, ocular motor and attentional systems were activated when the eyes were open. On the contrary, the visual, somatosensory, vestibular, and auditory systems were activated when the eyes were closed. In this study, we investigated whether cortical areas related to the olfactory and gustatory system are also animated by eye closure without any other external stimulation. In a first fMRI experiment (n = 22), we identified cortical areas including the piriform cortex activated by olfactory stimulation. In a second experiment (n = 12) subjects lying in darkness in the MRI scanner alternately opened and closed their eyes. In accordance to previous studies, we found activation clusters bilaterally in visual, somatosensory, vestibular and auditory cortical areas for the contrast eyes-closed vs. eyes-open. In addition, we were able to show that cortical areas related to the olfactory and gustatory system were also animated by eye closure. These results support the hypothesis that there are two different states of mental activity: with the eyes closed, an "interoceptive" state characterized by imagination and multisensory activity and with the eyes open, an "exteroceptive" state characterized by attention and ocular motor activity. Our study also suggests that the chosen baseline condition may have a considerable impact on activation patterns and on the interpretation of brain activation studies. This needs to be considered for studies of the olfactory and gustatory system.
在之前的两项功能磁共振成像（fMRI）研究中，据报道，在黑暗环境下睁眼和闭眼状态对大脑活动有不同影响，并识别出了典型的皮质活动模式。在没有外部刺激的情况下，睁眼时眼球运动和注意力系统被激活。相反，闭眼时视觉、体感、前庭和听觉系统被激活。在本研究中，我们调查了在没有任何其他外部刺激的情况下，与嗅觉和味觉系统相关的皮质区域是否也会因闭眼而活跃起来。在第一个fMRI实验（n = 22）中，我们识别出了包括梨状皮质在内的受嗅觉刺激激活的皮质区域。在第二个实验（n = 12）中，躺在MRI扫描仪黑暗环境中的受试者交替睁眼和闭眼。与之前的研究一致，我们发现闭眼与睁眼对比时，在视觉、体感、前庭和听觉皮质区域双侧均有激活簇。此外，我们能够证明与嗅觉和味觉系统相关的皮质区域也会因闭眼而活跃起来。这些结果支持了这样一种假设，即存在两种不同的心理活动状态：闭眼时，一种以想象和多感官活动为特征的“内感受性”状态；睁眼时，一种以注意力和眼球运动活动为特征的“外感受性”状态。我们的研究还表明，所选择的基线条件可能对激活模式以及大脑激活研究的解释有相当大的影响。对于嗅觉和味觉系统的研究需要考虑这一点。
