Consciousness and Name-Form In the twelve nidanas in the dependent origination it is said that through ignorance arises constructive activities (Sankskara). I do understand that. But the fact that I am still having trouble understanding is how Sankara causes the consciousness to arise and how consciousness cause the name and form to arise.

I do understand that cause of name-form the consciousness arises as these two are very interdependent. But my question is as the above.


How does Sankskara cause consciousness to arise? 
How does consciousness cause the name-form to arise?
In my interpretation (which is a product of my own vipassana), the translation and interpretation of nidanas is a little different. I tend to think of nidanas in terms of developmental psychology:


Avidya is innate ignorance, so far so good.
Sankskara is "imprint that creates subsequent tendency to react in a certain way". Kind of like memory but at a lower organizational level. So when there is ignorance, the interaction of primordial nature with itself leaves traces, which, given enough repetitions, eventually accumulate into tendencies and expectations. 
These tendencies and expectations get progressively more robust and integrated until they connect into full-fledged continuous experience ('vijnana'). This experience is not reality itself though, but an interpretation/projection assembled from the tendencies and expectations.
Through the same process of accumulation of sankskaras (which remain the underlying fabric comprising the experience) the whole process keeps on maturing until some of the tendencies and expectations crystallize to the status of objects ('namarupa'). These objects are second-order constructs - the signs (nimitta) that make up the original experience are further interpreted up the chain of abstraction. 


So in my interpretation the twelve nidanas describe the natural process by which the primordially impersonal becomes (first aware and then) personal.