CA3 projects Schaffer collaterals to apical dendrites in CA1. Individual pyramidal cells in the CA3 region have burst properties due to high densities of calcium channels in their proximal dendrites. Depolarization of the membrane may also trigger these bursts. Calcium entry into the cell causes more prolonged depolarization and increased action potentials. Usually curtailed by the hyperpolarizing local inhibition (due to the excitatory collateral system), this can lead to gradual recruitment of CA3 neurons and result in synchronized burst discharges. After hyperpolarization by calcium-dependent potassium conductance is also used as a method of controlling these bursts.