O'Callaghan Georgia, O'Dowd Alan, Simões-Franklin Cristina, Stapleton John, Newell Fiona N
Trinity College Institute of Neuroscience, School of Psychology, Trinity College Dublin, Dublin, Ireland.
Front Integr Neurosci. 2018 Jun 7;12:24. doi: 10.3389/fnint.2018.00024. eCollection 2018.
We investigated the neural underpinnings of texture categorisation using exemplars that were previously learned either within modalities (visual training and visual test) or across modalities (tactile training and visual test). Previous models of learning suggest a decrease in activation in brain regions that are typically involved in cognitive control during task acquisition, but a concomitant increase in activation in brain regions associated with the representation of the acquired information. In our study, participants were required to learn to categorise fabrics of different textures as either natural or synthetic. Training occurred over several sessions, with each fabric presented either visually or through touch to a participant. Pre- and post-training tests, in which participants categorised visual images only of the fabrics, were conducted during a functional magnetic resonance imaging (fMRI) scan. Consistent with previous research on cognitive processes involved in task acquisition, we found that categorisation training was associated with a decrease in activation in brain regions associated with cognitive systems involved in learning, including the superior parietal cortex, dorsal anterior cingulate cortex (dACC), and the right dorsolateral prefrontal cortex (DLFC). Moreover, these decreases were independent of training modality. In contrast, we found greater activation to visual textures in a region within the left medial occipital cortex (MOC) following training. There was no overall evidence of an effect of training modality in the main analyses, with texture-specific regional changes associated with both within- (visual) and cross- (touch) modal training. However, further analyses suggested that, unlike categorisation performance following within-modal training, crossmodal training was associated with bilateral activation of the MOC. Our results support previous evidence for a multisensory representation of texture within early visual regions of the cortex and provide insight into how multisensory categories are formed in the brain.
我们使用先前在模态内（视觉训练和视觉测试）或跨模态（触觉训练和视觉测试）学习的范例，研究了纹理分类的神经基础。先前的学习模型表明，在任务习得过程中，通常参与认知控制的脑区激活会减少，但与习得信息表征相关的脑区激活会相应增加。在我们的研究中，参与者被要求学习将不同质地的织物分类为天然或合成。训练分几个阶段进行，每种织物以视觉或触觉方式呈现给参与者。在功能磁共振成像（fMRI）扫描期间，进行了训练前和训练后的测试，参与者仅对织物的视觉图像进行分类。与先前关于任务习得中涉及的认知过程的研究一致，我们发现分类训练与与学习相关的认知系统脑区激活减少有关，包括顶上叶皮质、背侧前扣带回皮质（dACC）和右侧背外侧前额叶皮质（DLFC）。此外，这些减少与训练模态无关。相比之下，我们发现训练后左侧枕叶内侧皮质（MOC）内的一个区域对视觉纹理有更大的激活。在主要分析中，没有总体证据表明训练模态有影响，纹理特异性区域变化与模态内（视觉）和跨模态（触觉）训练都有关。然而，进一步分析表明，与模态内训练后的分类表现不同，跨模态训练与MOC的双侧激活有关。我们的结果支持了先前关于皮质早期视觉区域内纹理多感官表征的证据，并为大脑中多感官类别如何形成提供了见解。
