Now that we know what the nervous system is made of (e.g. neurons), what does that say about the relationship between the brain and behavior?

Being a member of the camp that does believe that the brain is behavior, I think that the interrelationship of the neurons to each other in such vast numbers reaffirms the claim that brain is behavior. Since we are talking about 1000000000000 neurons in the body, the combinations of pathways the the neurons can transmit from input to terminal output (is there such a thing) in incredible. These vast pathways can help to explain both random and predictible reactions.

The combination of both seemingly random behaviors like bouncing your knee up and down while typing on a computer along with predictible behaviors like blinking when an eyelash falls in your eye helps to display the complex workings of the neuron relationships. Why are there some occasions that are so unpredictible and other the are so? Does it have to do with a longer pathway between boxes in the system that allows for more variance in responses?

Another question: Are there biochemical explanations for the manner in which neurons display their output? For example, if you wake up in a rosebush (bear with me here) being stuck with thorns, the reaction may ternd to be of pain and surprize and you will tend to your wounds. But if you are running after your dog that got off of your leash and you run through the same rosebush and sustain the same physical injuries, will the reaction be the same, or do you continue chasing after Fido?

Nice question. We'll get to it (though in a different situation, less poetic). And the prior thoughts interesting too. I'm not sure bouncing your knee is so much "unpredictable" as usually unnoticed by you (I suspect your roommate can predict it). But the more general question, why are some things more predictable, others less so, remains. And probably doesn't have its explanation in pathway length (though that's a good starting hypothesis): there are some pretty short pathway length but variable behaviors. PG