All types of graded potentials will result in small changes of either depolarization or hyperpolarization in the voltage of a membrane. ... Graded potentials summate at a specific location at the beginning of the axon to initiate the action potential, namely the initial segment.

Can graded potentials be excitatory or inhibitory?

They arise from the summation of the individual actions of ligand-gated ion channel proteins, and decrease over time and space. They do not typically involve voltage-gated sodium and potassium channels. These impulses are incremental and may be excitatory or inhibitory.

Can graded potentials sum together?

The signals forming a graded potential can sum or negate one another, increasing or decreasing the possibility of reaching threshold to cause an action potential. There can be temporal summation (over time) or spatial summation (more than one signal).