Enhanced neural plasticity in monkey TE compared to TEO during learning of a feature-ambiguous visual categorization task

Primates can rapidly categorize images by visual feature similarity. We previously showed that inferior temporal cortex (IT) subregions TEO and TE contribute to visual categorization to differing extents. To investigate the neural plasticity underlying visual categorization, we recorded simultaneously from both areas while two male monkeys learned a visual categorization task. Category specificity and generalization are initially stronger in TEO than in TE but increase with learning only in the TE neuronal population, whose neural representations correlate with behavioral performance. TE and TEO can contribute complementary, partially independent category information. However, TEO does not add learning-relevant variance across days. TE exhibits greater categorical enhancement for correct than error trials compared with TEO. Single-neuron analyses revealed that TE category selectivity strengthens with learning, primarily through enhanced encoding of one category. Combined with lesion evidence, our results suggest that TE plasticity likely plays a more fundamental role in supporting visual category learning.

灵长类动物可通过视觉特征相似度快速对图像进行分类。我们此前的研究表明，颞下回（inferior temporal cortex, IT）的两个亚区TEO与TE在视觉分类任务中发挥的作用程度存在差异。为探究支撑视觉分类的神经可塑性机制，我们在两只雄性猕猴完成视觉分类任务学习的过程中，同时记录了这两个脑区的神经活动。在学习初期，TEO的类别特异性与泛化能力均强于TE；但仅在TE的神经元群体中，上述两项指标会随学习进程提升，且该脑区的神经表征与行为表现存在相关性。TE与TEO可提供互补且部分独立的类别信息，但在多日训练过程中，TEO并未引入与学习相关的神经变异。相较于TEO，TE在正确试次中的类别增强效应显著强于错误试次。单神经元分析结果显示，TE的类别选择性随学习进程增强，这一过程主要通过强化对单一类别的编码实现。结合损毁实验证据，本研究结果表明，TE的神经可塑性可能在支撑视觉类别学习中发挥更为核心的作用。