A Model of Cooperative Effect of AMPA and NMDA Receptors in Glutamatergic Synapses

Glutamatergic synapses play a pivotal role in brain excitation. The synaptic response is mediated by the activity of two receptor types (AMPA and NMDA). In the present paper we propose a model of glutamatergic synaptic activity where the fast current generated by the AMPA conductance produces a local depolarization which activates the voltage- and $[Mg^{2+}]$-dependent NMDA conductance. This cooperative effect is dependent on the biophysical properties of the synaptic spine which can be considered a high input resistance specialized compartment. Herein we present results of simulations where different values of the spine resistance and of the $Mg^{2+}$ concentrations determine different levels of cooperativeness between AMPA and NMDA receptors in shaping the post-synaptic response.