Graded potential

They arise from the summation of the individual actions of ligand-gated ion channel proteins, and decrease over time and space.

Graded potentials are usually produced in the dendrites of a neuron where voltage-gated channels are not present.

They are localized changes in the membrane potential in response to a stimuli, like neurotransmitters binding to receptor.

The transmitter diffuses across the synaptic cleft and activates ligand-gated ion channels that mediate the EPSP.

As with EPSPs, the amplitude of the IPSP is directly proportional to the number of synaptic vesicles that were released.