Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
Department of Psychology, Rhodes College, Memphis, TN, USA.
Nat Neurosci. 2023 Sep;26(9):1595-1602. doi: 10.1038/s41593-023-01414-4. Epub 2023 Aug 24.
Odor perception is inherently subjective. Previous work has shown that odorous molecules evoke distributed activity patterns in olfactory cortices, but how these patterns map on to subjective odor percepts remains unclear. In the present study, we collected neuroimaging responses to 160 odors from 3 individual subjects (18 h per subject) to probe the neural coding scheme underlying idiosyncratic odor perception. We found that activity in the orbitofrontal cortex (OFC) represents the fine-grained perceptual identity of odors over and above coarsely defined percepts, whereas this difference is less pronounced in the piriform cortex (PirC) and amygdala. Furthermore, the implementation of perceptual encoding models enabled us to predict olfactory functional magnetic resonance imaging responses to new odors, revealing that the dimensionality of the encoded perceptual spaces increases from the PirC to the OFC. Whereas encoding of lower-order dimensions generalizes across subjects, encoding of higher-order dimensions is idiosyncratic. These results provide new insights into cortical mechanisms of odor coding and suggest that subjective olfactory percepts reside in the OFC.
嗅觉感知本质上是主观的。先前的研究表明,有气味的分子会在嗅觉皮层中引发分布式活动模式,但这些模式如何映射到主观的嗅觉感知上尚不清楚。在本研究中,我们从 3 名个体(每位个体 18 小时)中收集了对 160 种气味的神经影像学反应,以探究个体嗅觉感知背后的神经编码方案。我们发现,眶额皮层(OFC)的活动不仅可以代表气味的粗略感知,还可以代表气味的精细感知,而在梨状皮层(PirC)和杏仁核中,这种差异则不那么明显。此外,实施感知编码模型使我们能够预测新气味的嗅觉功能磁共振成像反应,这表明编码的感知空间的维度从 PirC 到 OFC 逐渐增加。虽然较低阶维度的编码可以跨个体概括,但高阶维度的编码是个体特有的。这些结果为嗅觉编码的皮质机制提供了新的见解,并表明主观嗅觉感知存在于 OFC 中。