When the glutamate molecule binds to a glutamate receptor embedded on the membrane of the receiving nerve cell, the receptor opens channels in the membrane that allow calcium ions to flow into the cell. The influx of charge causes a voltage to build up across the cell membrane, and the nerve cell fires, passing the signal on to the next nerve cell. Frequent stimulation can cause new connections to grow between the neurons, so glutamate plays a fundamental role in thought, learning and memory. It is possible to have too much of a good thing, however. Glutamate at high concentrations acts as an excitotoxin -a compound that kills cells by literally exciting them to death.
Excess glutamate keeps the gates that allow calcium ions across the cell membrane open too long.
Calcium ions flood into the cell, causing it fire uncontrollably. The neuron swells and eventually bursts. The damage cascades to nearby neurons because the damaged and ruptured neurons release their glutamate and other excitatory amino acids, overstimulating nearby cells. This excitotoxic cascade is thought to play an important role in brain injury and neurodegenerative diseases. Domoic acid's structure is obviously similar to glutamic acid.