I just got into neuroscience like a couple of months ago, but I can't, for the life of me, figure this out. Wouldn't it take a humongous amount of action-potentials in, for example, the thalamus for a small number of neurons to fire at the opposite end of the brain in the frontal cortex? Also, usually, signals travel from the cortex back to the thalamus, so is it possible for signals to get boosted in some way? It just seems there wouldn't be enough action-potentials for there to be any circuitry in the brain.
Edit: My thought process is very mathematical, and I didn't think about temporal summation when thinking about this, but let's say, for example, that it takes 4 APs to fire a single neuron. That would mean that y = x/4, with y being the amount of output APs and x being the amount of input APs. Let's say that 100 million neurons need to fire to reach the end of the frontal cortex. That would mean you'd need 400 million input APs in total to reach the end of the frontal cortex. That seems like a lot, but while typing this, I feel like my grasp of some of the more basic aspects of neuroscience isn't really that great. I'm self-teaching so maybe that has something to do with it.