Flavor pleasantness processing in the ventral emotion network

The ventral emotion network–encompassing the amygdala, insula, ventral striatum, and ventral regions of the prefrontal cortex–has been associated with the identification of emotional significance of perceived external stimuli and the production of affective states. Functional magnetic resonance imaging (fMRI) studies investigating chemosensory stimuli have associated parts of this network with pleasantness coding. In the current study, we independently analyzed two datasets in which we measured brain responses to flavor stimuli in young adult men. In the first dataset, participants evaluated eight regular off the shelf drinking products while participants evaluated six less familiar oral nutritional supplements (ONS) in the second dataset. Participants provided pleasantness ratings 20 seconds after tasting. Using independent component analysis (ICA) and mixed effect models, we identified one brain network in the regular products dataset that was associated with flavor pleasantness. This network was very similar to the ventral emotion network. Although we identified an identical network in the ONS dataset using ICA, we found no linear relation between activation of any network and pleasantness scores within this dataset. Our results indicate that flavor pleasantness is processed in a network encompassing amygdala, ventral prefrontal, insular, striatal and parahippocampal regions for familiar drinking products. For more unfamiliar ONS products the association is not obvious, which could be related to the unfamiliarity of these products.

腹侧情绪网络（ventral emotion network）涵盖杏仁核、岛叶、腹侧纹状体及前额叶皮层腹侧区域，此前被证实与感知外部刺激的情绪意义识别及情感状态生成相关。针对化学感应刺激的功能磁共振成像（fMRI）研究已将该网络的部分区域与愉悦度编码建立关联。本研究对两组独立数据集开展独立分析，两组数据集均测量了年轻成年男性对风味刺激的脑响应。第一组数据集内，受试者对8种常规市售饮用产品进行评估；第二组数据集内，受试者则评估了6种相对陌生的口服营养补充剂（ONS）。所有受试者均在品尝后20秒给出愉悦度评分。本研究采用独立成分分析（ICA）与混合效应模型，在市售产品数据集中识别出一个与风味愉悦度相关的脑网络，该网络与腹侧情绪网络高度相似。尽管在口服营养补充剂数据集的ICA分析中同样识别出了完全一致的脑网络，但本研究未发现该数据集中任一网络的激活水平与愉悦度评分存在线性关联。研究结果显示：对于熟悉的常规市售饮用产品，其风味愉悦度的加工涉及涵盖杏仁核、腹侧前额叶、岛叶、纹状体及海马旁回区域的脑网络；而针对相对陌生的口服营养补充剂，上述关联并不显著，这或与这类产品的陌生性相关。