How long does a spiking signal last?
Effective integration time of a typical neuron is in the order of 10-100 ms. You might want to look into this classic paper (read it with a critical mindset):


Shadlen, M. N. and Newsome, W. T. (1994). Noise, neural codes and cortical organization. Curr. Opin. Neurobiol., 4:569-579.


Or some biophysics book like:


Biophysics of Computation by Christof Koch