·就人类而言，触觉是胎儿在子宫中第一个开始发挥作用的感官，大约在8周，胎儿的触觉就形成了。不同的部位对应着不同的大脑体感皮层的部位。而我们之所以能有意识地察觉到皮肤上特定位置的触感，是因为皮层里有一组特定神经元被激活了。在人的一生中，其触摸的脑图并不是固定不变的，其会随着人感官体验的变化而不断变化。

参考资料：

[1] Murphy M L M, Janicki-Deverts D, Cohen S. Receiving a hug is associated with the attenuation of negative mood that occurs on days with interpersonal conflict[J]. PloS one, 2018, 13(10): e0203522.

[2] Carter C S, Kenkel W M, MacLean E L, et al. Is oxytocin “nature’s medicine”?[J]. Pharmacological reviews, 2020, 72(4): 829-861.

[3] https://www.wired.com/story/the-neuroscience-of-why-you-could-really-use-a-hug-right-now/

[4] https://www.nytimes.com/1988/02/02/science/the-experience-of-touch-research-points-to-a-critical-role.html

[5] 《触感引擎》

[6] Thomas P A, Kim S. Lost touch? Implications of physical touch for physical health[J]. The Journals of Gerontology: Series B, 2021, 76(3): e111-e115.