Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium.
Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium
J Neurosci. 2018 Apr 11;38(15):3689-3707. doi: 10.1523/JNEUROSCI.1587-17.2018. Epub 2018 Mar 14.
Neurophysiological data obtained in primates suggests that merely observing others' actions can modulate activity in the observer's motor cortices. In humans, it has been suggested that these multimodal vicarious responses extend well beyond the motor cortices, including somatosensory and insular brain regions, which seem to yield vicarious responses when witnessing others' actions, sensations, or emotions (Gazzola and Keysers, 2009). Despite the wealth of data with respect to shared action responses in the monkey motor system, whether the somatosensory and insular cortices also yield vicarious responses during observation of touch remains largely unknown. Using independent tactile and motor fMRI localizers, we first mapped the hand representations of two male monkeys' primary (SI) and secondary (SII) somatosensory cortices. In two subsequent visual experiments, we examined fMRI brain responses to (1) observing a conspecific's hand being touched or (2) observing a human hand grasping or mere touching an object or another human hand. Whereas functionally defined "tactile SI" and "tactile SII" showed little involvement in representing observed touch, vicarious responses for touch were found in parietal area PFG, consistent with recent observations in humans (Chan and Baker, 2015). Interestingly, a more anterior portion of SII, and posterior insular cortex, both of which responded when monkeys performed active grasping movements, also yielded visual responses during different instances of touch observation. Common coding of one's own and others' actions, sensations, and emotions seems to be widespread in the brain. Although it is currently unclear to what extent human somatosensory cortices yield vicarious responses when observing touch, even less is known about the presence of similar vicarious responses in monkey somatosensory cortex. We therefore localized monkey somatosensory hand representations using fMRI and investigated whether these regions yield vicarious responses while observing various instances of touch. Whereas "tactile SI and SII" did not elicit responses during touch observation, a more anterior portion of SII, in addition to area PFG and posterior insular cortex, all of which responded during monkeys' own grasping movements, yielded vicarious responses during observed touch.
在灵长类动物身上获得的神经生理学数据表明，仅仅观察他人的动作就可以调节观察者运动皮层的活动。在人类中，有人认为这些多模态的替代反应远远超出了运动皮层，包括躯体感觉和脑岛区域，当观察他人的动作、感觉或情绪时，这些区域似乎会产生替代反应（Gazzola 和 Keysers，2009）。尽管猴子运动系统中关于共享动作反应的数据丰富，但在观察触摸时，躯体感觉和脑岛皮层是否也会产生替代反应，在很大程度上仍然未知。使用独立的触觉和运动 fMRI 定位器，我们首先绘制了两只雄性猴子初级（SI）和次级（SII）躯体感觉皮层的手部代表区。在随后的两个视觉实验中，我们检查了 fMRI 大脑对（1）观察同类动物的手被触摸或（2）观察人手抓握或仅仅触摸物体或另一只人手的反应。虽然功能定义的“触觉 SI”和“触觉 SII”在手部触摸的代表中几乎没有参与，但在顶下小叶（PFG）区域发现了触摸的替代反应，这与最近人类的观察结果一致（Chan 和 Baker，2015）。有趣的是，SII 的更靠前部分和后脑岛，在猴子进行主动抓握运动时都有反应，在不同的触摸观察实例中也产生了视觉反应。对自己和他人的动作、感觉和情绪的共同编码似乎在大脑中广泛存在。虽然目前尚不清楚人类躯体感觉皮层在观察触摸时会产生多大程度的替代反应，但猴子躯体感觉皮层中是否存在类似的替代反应知之甚少。因此，我们使用 fMRI 定位了猴子的躯体感觉手部代表，并研究了这些区域在观察各种触摸实例时是否会产生替代反应。虽然“触觉 SI 和 SII”在触摸观察期间没有产生反应，但 SII 的更靠前部分，除了 PFG 区域和后脑岛，这些区域在猴子自己的抓握运动中都有反应，在手部观察期间产生了替代反应。
