Figure 5.

Plasticity of membrane excitability is not dependent upon NMDA receptors. A, In the presence of MK-801 intracellular (depicted here) or extracellular or high intracellular levels of Mg²⁺ to block NMDA receptors, TBF still caused a decrease of membrane excitability. B, Plotted over time, neither Mg²⁺ nor MK801 fully blocked TBF-induced reductions of membrane excitability. C, Blockade of NMDA receptors does not block changes of membrane properties caused by theta burst firing. When NMDA channels are blocked (in this instance with intracellular MK-801), theta burst firing still effectively reduces input resistance and membrane time constant.