Question

The NMDA receptor controls ______ and is normally blocked by ______.

a. a calcium channel; magnesium ions
b. a chloride channel; sodium ions
c. the presynaptic membrane potential; GABA
d. the inputs to the hippocampus; presynaptic inhibition
e. a potassium channel; magnesium ions

Answer 1

The NMDA receptor is a calcium channel that controls synaptic plasticity and is normally blocked by magnesium ions. The receptor is activated by glutamate binding, after depolarization removes inhibitory magnesium ions and allows calcium to enter the cell. This calcium influx can initiate long-term potentiation (LTP) or long-term depression (LTD).

Step-by-step explanation:

The NMDA receptor is a calcium channel that controls synaptic plasticity and is normally blocked by magnesium ions.

The NMDA receptor is activated by glutamate binding, but only after depolarization removes inhibitory Mg2+. Once the Mg2+ is removed, Ca²+ can enter the cell, leading to a rise in intracellular calcium concentration.

This calcium influx through NMDA receptors can initiate two forms of synaptic plasticity: long-term potentiation (LTP) and long-term depression (LTD). LTP leads to the insertion of more AMPA receptors into the postsynaptic membrane, while LTD results in the endocytosis of AMPA receptors.