Chan Jason S, van den Bosch Jasper J F, Theves Stephanie, Hardt Stefanie, Pflanz Patrick, Lötsch Jörn, Kaiser Jochen, Naumer Marcus J
Institute of Medical Psychology, Goethe-University of Frankfurt, Frankfurt am Main, Germany.
Multisens Res. 2014;27(3-4):225-46. doi: 10.1163/22134808-00002451.
The most common form of synaesthesia is grapheme-colour synaesthesia. However, rarer forms of synaesthesia also exist, such as word-gustatory and olfactory-gustatory synaesthesia, whereby a word or smell will induce a specific. In this study we describe a single individual (LJ) who experiences a concurrent olfactory stimulus when presented with congruent visual images. For some visual stimuli, he perceives a strong and automatic olfactory percept, which has existed throughout his life. In this study, we explore whether his experiences are a new form of synaesthesia or simply vivid imagery. Unlike other forms of synaesthesia, the concurrent odour is congruent to the visual inducer. For example, a photograph of dress shoes will elicit the smell of leather. We presented LJ and several control participants with 75 images of everyday objects. Their task was to indicate the strength of any perceived odours induced by the visual images. LJ rated several of the images as inducing a concurrent odour, while controls did not have any such percept. Images that LJ reported as inducing the strongest odours were used, along with colour-matched control images, in the context of an fMRI experiment. Participants were given a one-back task to maintain attention. A block-design odour localizer was presented to localize the piriform cortex (primary olfactory cortex). We found an increased BOLD response in the piriform cortex for the odour-inducing images compared to the control images in LJ. There was no difference in BOLD response between these two stimulus types in the control participants. A subsequent olfactory imagery task did not elicit enhanced activity in the piriform cortex in LJ, suggesting his perceptual experiences may not be based on olfactory imagery.
最常见的联觉形式是字形 - 颜色联觉。然而，也存在较罕见的联觉形式，如字词 - 味觉和嗅觉 - 味觉联觉，即一个单词或气味会引发一种特定的感觉。在本研究中，我们描述了一个个体（LJ），当呈现一致的视觉图像时，他会同时经历嗅觉刺激。对于某些视觉刺激，他会感知到一种强烈且自动产生的嗅觉感受，这种感受伴随他一生。在本研究中，我们探讨他的这些体验是一种新的联觉形式还是仅仅是生动的意象。与其他联觉形式不同，同时出现的气味与视觉诱导物是一致的。例如，一张皮鞋的照片会引发皮革的气味。我们向LJ和几位对照参与者展示了75张日常物品的图片。他们的任务是指出视觉图像所引发的任何感知到的气味的强度。LJ将几张图片评为引发了同时出现的气味，而对照参与者则没有任何此类感受。在功能磁共振成像（fMRI）实验中，使用了LJ报告引发最强气味的图片以及颜色匹配的对照图片。参与者被给予一个“1-back”任务以保持注意力。呈现一个组块设计的气味定位任务来定位梨状皮质（初级嗅觉皮质）。我们发现，与对照图片相比，LJ中引发气味的图片在梨状皮质中产生了增强的血氧水平依赖（BOLD）反应。对照参与者中这两种刺激类型之间的BOLD反应没有差异。随后的嗅觉意象任务在LJ的梨状皮质中并未引发增强的活动，这表明他的感知体验可能不是基于嗅觉意象。
