Ghost resonance in a pool of heterogeneous neurons

We numerically study the subharmonic response of a heterogeneous pool of neurons
to a pair of independent inputs. The neurons are stimulated with periodic pulse
trains of frequencies f1 = 2 Hz and f2 = 3 Hz, and with inharmonic pulses whose
frequencies f1 and f2 are equally shifted an amount f. When both inputs are
subthreshold, we find that the neurons respond at a frequency equal to f2−f1 in the
harmonic situation (f = 0), that increases linearly with f in the inharmonic case.
Thus the neurons detect a frequency not present in the input; this effect is termed
“ghost resonance”. When one of the inputs is slightly suprathreshold the ghost
resonance persists, but responses related with the frequency of the suprathreshold
input also emerge. This behavior must be taken into account in experimental studies
of signal integration and coincidence detection by neuronal pools.