Why is the AMPA current over within a few milliseconds of glutamate release? · Grey Matter

Glutamate in the cleft reaches a high concentration for only about a millisecond before it diffuses away and is taken up by transporters, and AMPA receptors bind it with low affinity, so they let go quickly.

Why is the AMPA current over within a few milliseconds of glutamate release?

Glutamate in the cleft reaches a high concentration for only about a millisecond before it diffuses away and is taken up by transporters, and AMPA receptors bind it with low affinity, so they let go quickly. Those that stay bound close anyway within milliseconds by desensitising. The current therefore decays with a time constant of roughly one to a few milliseconds, and below a millisecond at some fast synapses onto interneurons. The brevity is what lets AMPA synapses carry precise timing, while the slower NMDA current beside them integrates over a hundred milliseconds or so.