Long-term potentiation (LTP) in the hippocampus requires initial activation of AMPA receptors followed by relief of Mg²⁺ block from which receptor, enabling Ca²⁺ influx as the key trigger for synaptic strengthening?
- A Kainate receptor (GluK1-5 subunit-containing ionotropic glutamate receptor)
- B NMDA receptor (GluN1/GluN2 subunit-containing ionotropic glutamate receptor) ✓
- C GABAB receptor (metabotropic, Gi-coupled, reducing cAMP)
- D mGluR1 (metabotropic glutamate receptor Group I, Gq-coupled)
Explanation
LTP requires a coincidence detector: AMPA receptor activation provides initial depolarization that relieves the voltage-dependent Mg²⁺ block of the NMDA receptor channel. With both glutamate binding and membrane depolarization, the NMDA receptor conducts Ca²⁺ into the postsynaptic neuron. Ca²⁺ activates CaMKII (calcium/calmodulin-dependent protein kinase II), which phosphorylates AMPA receptors (increasing conductance) and triggers AMPA receptor trafficking to the synapse — increasing synaptic strength. This Hebbian plasticity mechanism is the cellular basis of declarative memory in the hippocampus.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.