The influence of noise on the dynamics of a two-dimensional neural map with self-sustained subthreshold oscillations is studied by numerical simulation. When the injected current is absent and the control parameter is located in the silence region, numerical results show that stochastic oscillations of the membrane potential can be induced by noise. Moreover, the coherence of such oscillations shows two maxima with the variation of the noise strength. The effect of control parameter on the dynamics of the system has also been investigated. Interestingly, it is found that the occurrence of coherence bi-resonance is closely associated with the distinct characteristics of the bifurcation of the deterministic dynamics.