neuron mechanics
The diagram (attachment) is self-explanatory.
Nevertheless, essentially the nerve impulse is a sudden rush of sodium ions. The rush then triggers the next few proteins to let in more ions. This process continues in a relay fashion until the pulse reaches the presynaptic membrane. As soon as the pulse passes an indicated area of proteins, they will immediately stop allowing sodium into the pathway. Then active transport kicks in via the sodium potassium pump and resets the nerve. This entire process occurs at about 100m/sec. (much slower than the speed of light).
For those of you that are curious about claims that nerves are electric well, here is the explination. The axon has positive ions on the outside and negative ions on the inside. This creates an electric potential. So then, why doesn’t the pulse travel at the speed of electricity? Well, the protein gates that keep the ions out have different ways of being activated, chemically, and electrically. The main pulse is mostly controlled by electrically activated proteins. However, they have a high "Tolerance.” That is, while they can "feel" the pulse coming via the weakened electric current, they do not activate until the pulse is near to them. Ultimately, the signal sent across the synaptic cleft is chemical. Thus, it would seem to be inefficient to keep changing the signal medium. However, there are some organisms that do have nerve that rely solely on electricity.
This electric method is fast but it does not integrate information well. Electric transmission across synapsises is very fast and can proceed in either direction. However, they are less common in vertebrates and other organisms that have complex nervous systems. First, electrical continuity between neurons does not allow temporal summation of synaptic inputs (one way that signals are integrated). Second, an effective electrical synapsis requires a larger area of contact between the cells. This makes it impossible to have thousands of connections coming from one cell (witch is common in vertebrates). Third, electrical synapses cannot be inhibitory (not allowing for complex brain chemistry); and fourth, there is little plasity (modifiability) of connections (much harder to learn). Essentially, all there good for if speed, but not so good for complexity.
The statistic I got for brain speed came from a friend of mine, ill try to contact him about his source whenever he is back from the holidays.
The question "do computer think faster than us?"
Well, yes and no. They are capable of transferring information faster than we are, and are faster at processing in a linear fashion. However, they are much slower when it comes to nonlinear systems and processing also known as thought. Simply computers "think" what we program them to. So yes, computers process linear equations faster than we process, but could never understand their environment (at least with current tech).
As far as either building or emulating a brain, I think we should start small. We should try to create something called a ganglion. A Ganglion is simply a small cluster of nerve cells that carry out a specific task. These tasks could be something simple like detecting danger then relaying the signal, of cause the creature to disengage itself from prey. This simple basis of neuro-networking would not allow the subsequent computers to gain emotions or anything and would be reacting on instinct. Thus it wouldn’t decide one day that it no longer likes the scientists and lock them out side the space craft... “HAL. Let me in”...
Another interesting thing to put to the test would be what the DNA says about creating a brain. I mean, it eventually has to do it some way or the other.