How does neural spiking begin in the fetus?

I'm interested in modeling human brain spiking activity. How does the very first spiking activity begin in the fetus?

I imagine all spiking activity is initiated by the senses and internal oscillators. Am I right? Or are there other initiators of spiking activity?

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See my answer to your other question for some insights into this. – Chuck Sherrington Mar 23 '12 at 8:28
@jonsca since the user seems unresponsive, I would suggest just explaining the relevant details of your other answer. It seems that the message there was along the lines of "neurons want to fire if conditions permit". – Artem Kaznatcheev Mar 28 '12 at 15:46
@JohnPick can you provide a reference for all spiking ceasing as described in point 2? – Artem Kaznatcheev Mar 28 '12 at 15:47
@ArtemKaznatcheev A reference for point 2? No. Perhaps a separate question is warranted to check if point 2 is valid. – John Pick Mar 28 '12 at 15:50
@JohnPick then don't include statements you don't know the validity of in your question unless they ARE your question. Without point 2 your question should be completely restated to only point 1, as "How does neural spiking begin in the fetus?" – Artem Kaznatcheev Mar 28 '12 at 15:54

Nice job with this one! I would have missed the tend to have their spontaneous firing resemble what their typical sensory production will look like in the future piece had I expanded on my other answer. – Chuck Sherrington Apr 29 '12 at 8:46