Question

Use the drop-down menus to indicate whether each of the following scenarios would likely lead to LTP or LTD at a glutamatergic synapse that contains both AMPA and NMDA receptors: [Select] 1 pulse/sec tetanic stimulation of presynaptic neurons [Select] Activation of kinases [Select] A weak influx of calcium [Select] More NMDA receptors with NR2A (open for less time) than NR2B subunits

a) LTP, LTD, LTP, LTD
b) LTD, LTP, LTD, LTP
c) LTP, LTP, LTD, LTD
d) LTD, LTD, LTP, LTP

Answer 1

Long-term Potentiation (LTP) strengthens synaptic connections by increasing the number of AMPA receptors, while Long-term Depression (LTD) weakens synaptic connections by removing AMPA receptors.

Step-by-step explanation:

Long-term Potentiation (LTP) is a persistent strengthening of a synaptic connection. LTP is based on the Hebbian principle: cells that fire together wire together. One mechanism involves NMDA receptors, which are normally blocked by magnesium ions. When depolarization occurs, calcium ions can enter the postsynaptic cell and initiate a signaling cascade that results in the insertion of more AMPA receptors into the postsynaptic membrane. This strengthens the synapse and makes the postsynaptic neuron more likely to fire in response to neurotransmitter release.

On the other hand, Long-term Depression (LTD) is a long-term weakening of a synaptic connection. It can occur when there is a low firing rate of the presynaptic neuron, resulting in a weak influx of calcium through the NMDA receptors. This activates a different signaling cascade that leads to the removal of AMPA receptors from the postsynaptic membrane, making the postsynaptic neuron less responsive to neurotransmitter release.