  We study the effect that the heterogeneity present among the elements of an
ensemble of coupled excitable neurons have on the collective response of the
system to an external signal. We have considered two different interaction
scenarios, one in which the neurons are diffusively coupled and another in
which the neurons interact via pulse-like signals. We found that the type of
interaction between the neurons has a crucial role in determining the response
of the system to the external modulation. We develop a mean-field theory based
on an order parameter expansion that quantitatively reproduces the numerical
results in the case of diffusive coupling.
