Eccles J C
Max-Planck-Institute for Brain Research, Frankfurt/Main, Federal Republic of Germany.
Proc Natl Acad Sci U S A. 1992 Aug 15;89(16):7320-4. doi: 10.1073/pnas.89.16.7320.
The hypothesis of the origin of consciousness is built upon the unique properties of the mammalian neocortex. The apical dendrites of the pyramidal cells bundle together as they ascend to lamina I to form neural receptor units of approximately 100 apical dendrites plus branches receiving hundreds of thousands of excitatory synapses, the collective assemblage being called a dendron. It is proposed that the whole world of consciousness, the mental world, is microgranular, with mental units called psychons, and that in mind-brain interaction one psychon is linked to one dendron through quantum physics. The hypothesis is that in mammalian evolution dendrons evolved for more effective integration of the increased complexity of sensory inputs. These evolved dendrons had the capacity for interacting with psychons that came to exist, so forming the mental world and giving the mammal conscious experiences. In Darwinian evolution, consciousness would have occurred initially some 200 million years ago in relation to the primitive cerebral cortices of evolving mammals. It would give global experiences of a surrounding world for guiding behavior beyond what is given by the unconscious operation of sensory cortical areas per se. So conscious experiences would give mammals evolutionary advantage over the reptiles, which lack a neocortex giving consciousness. The Wulst of the avian brain needs further investigation to discover how it could give birds the consciousness that they seem to have.
意识起源的假说建立在哺乳动物新皮层的独特属性之上。锥体细胞的顶端树突在向上延伸至第I层时聚集在一起,形成由大约100个顶端树突及其分支组成的神经受体单元,这些分支接收数十万的兴奋性突触,这个集合体被称为树突群。有人提出,整个意识世界,即精神世界,是由称为心理子的微小颗粒组成的,并且在脑-心相互作用中,一个心理子通过量子物理学与一个树突群相连。该假说认为,在哺乳动物的进化过程中,树突群进化是为了更有效地整合日益复杂的感觉输入。这些进化后的树突群有能力与后来出现的心理子相互作用,从而形成精神世界并赋予哺乳动物有意识的体验。在达尔文式的进化中,意识最初可能在大约2亿年前随着进化中的哺乳动物的原始大脑皮层而出现。它会提供周围世界的整体体验,以指导行为,而不仅仅是感觉皮层区域本身的无意识运作所提供的信息。因此,有意识的体验会使哺乳动物相对于缺乏能产生意识的新皮层的爬行动物具有进化优势。鸟类大脑的中脑视叶需要进一步研究,以发现它如何能赋予鸟类似乎具有的意识。