Table 1 Distinguishing features of depolarizations of action potentials and cortical spreading depression

Duration

1 ms

Up to 345.000 ms

Membrane conductance

Increased passage of specific ions Na+, K+, Ca++ through their ionic gradients

Complete loss of membrane resistance and ionic gradients across cell membrane

Functional consequence

Excitation

Loss of function, no reactivity of the cell membrane, prolonged silence

Signal transmission

Axonal hillock to synaptic release of neurotransmitters to active postsynaptic neuron

Release of neurotransmitters and K+ and other molecules from cell and contiguous spread to neighbor cells

Extracellular DC potential change

None

Up to 30 mV

Recovery period

After a few ms

Reappearance of spontaneous APs takes minutes, spontaneous EPSP/IPSPs improvement lasts hours