Channels in the membrane of the neuron allow ions to flow between the inside and outside of the cell. of these, open only when certain electrical conditions are met.

The correct term to fill in the blank would be voltage dependent channels. Channels in the membrane of the neuron allow ions to flow between the inside and outside of the cell. of these, voltage dependent channels open only when certain electrical conditions are met. These channels are transmembrane proteins that are activated by the changes in the electrical potential near it. The electric potential would alter the conformation of the proteins which in turn would regulate the closing and opening of the channels. The change in the electric potential is called the depolarization. Most of these channels are ion-specific like for the ions, calcium, sodium, chloride and potassium. 

Where are they though?

It is platinum in the market value