Several factors determine when, and how, neurons discharge in response to acoustic stimuli.
Chief among these are the types of synaptic inputs elicited. IPSPs are the fastest means to excite or inhibit, respectively, cortical neurons. Integration of EPSPs and IPSPs determine if neurons do, or do not, discharge, and temporal and spatial summation of inputs play an important role. Thus, bursts of excitatory inputs are more likely to excite cortical neurons than an equal number of inputs discharging at longer intervals, due to the effects of nonlinear summation. Conversely, IPSPs can inhibit primarily by two mechanisms, hyperpolarizing and shunting.