The interaction between neurons in a neuronal network develops spontaneous electrical activities. But the effects of electromagnetic radiation on these activities have not yet been well explored. In this study, a ring of three coupled 1-dimensional Rulkov neurons is considered and then exposed to an electromagnetic eld (EMF) to investigate how its spontaneous activities might change regarding the EMF exposure. By employing the bifurcation analysis and time series, a comprehensive view of neuronal behavioral changes due to electromagnetic radiations is provided. It is demonstrated that exposure to these EMFs may inhibit chaotic neuronal behaviors when the neuronal network is supposed to develop a chaotic behavior spontaneously. In fact, EMFs completely eliminated the chaotic intrinsic behaviors of the neuronal loop. On the other hand, due to this exposure, the development of chaotic regimes is seen when the network is supposed to show regular spiking behaviors. Furthermore, it is observed that with weaker synaptic couplings, electromagnetic radiation inhibits and suppresses neuronal activities. On the whole, electromagnetic radiation may change the pattern of the spontaneous activities of neuronal networks in the brain according to synaptic strengths and initial states of the neurons.