Question

Which statement about long-term potentiation (LTP) is false? A. During normal, low-level activity, the release of glutamate at the synapse activates only the AMPA receptors. B. NMDA receptors cannot ordinarily respond to glutamate because magnesium ions block the NMDA receptor's calcium ion channel. C. Strong stimulation of AMPA receptors depolarizes the postsynaptic membrane so much that the Mg2+ plug is driven from the central channels of the NMDA receptors. D. NMDA receptors are fully active only when 'gated' by a strong depolarization (via AMPA receptors) and the ligand calcium.

Answer 1

The correct answer is: D. NMDA receptors are fully active only when 'gated' by a strong depolarization (via AMPA receptors) and the ligand calcium.

NMDA receptors or N-methyl-D-aspartate receptors are ionotropic glutamate receptors.

Those receptors are inactive at the resting potential, because channel pore is blocked by magnesium ions, preventing ion flows through it. After the depolarization (AMPA receptor mediated) of the post-synaptic cell, the channel inhibition is released and thus NMDA receptor is activated. Also, the receptor is activated when glycine and glutamate bind to it.

When it is activated, the receptor channel allows the flow of cations K+, Na+ and Ca2+. The influx of Ca2+, which is secondary messenger, triggers intracellular signaling pathways.