A commonly pursued goal in studying synaptic plasticity is to determine whether synaptic inputs undergo presynaptic and/or postsynaptic alterations following a stimulus and how these alterations affect the firing properties of the innervated neuron. In this chapter, we continue to discuss approaches that can be implemented to test presynaptic mechanisms of plasticity. In addition, we explain modifications that can occur in the postsynaptic cell affecting the intrinsic membrane excitability. Related to this, we discuss the voltage-gated channels that regulate the intrinsic membrane excitability and how these channels contribute to EPSP summation at the soma and back-propagating action potentials. We conclude this chapter with approaches that can be used to measure the intrinsic membrane excitability.