Which of the following is a likely mechanism for long-term...

Which of the following is a likely mechanism for long-term potentiation? a. When glutamate binds to postsynaptic AMPA receptors, it activates G proteins that trigger intracellular changes. b. When glutamate binds to NMDA receptors, it allows $\mathrm{Mg}^{2+}$ ions to enter the cell, which initiate intracellular changes. c. When sufficient glutamate is released by the presynaptic cell, it causes an increase in the number of AMPA receptors on the postsynaptic cell. d. When sufficient glutamate is released, both AMPA and NMDA receptors are activated, and NMDA receptors allow $\mathrm{Ca}^{2+}$ as well as $\mathrm{Na}^{+}$ to enter the cell, thus initiating intracellular changes. e. When both glutamate and acetylcholine are released together, they create a long-lasting depolarization of the postsynaptic cell.

Which of the following is a likely mechanism for long-term potentiation?
a. When glutamate binds to postsynaptic AMPA receptors, it activates G proteins that trigger intracellular changes.
b. When glutamate binds to NMDA receptors, it allows $\mathrm{Mg}^{2+}$ ions to enter the cell, which initiate intracellular changes.
c. When sufficient glutamate is released by the presynaptic cell, it causes an increase in the number of AMPA receptors on the postsynaptic cell.
d. When sufficient glutamate is released, both AMPA and NMDA receptors are activated, and NMDA receptors allow $\mathrm{Ca}^{2+}$ as well as $\mathrm{Na}^{+}$ to enter the cell, thus initiating intracellular changes.
e. When both glutamate and acetylcholine are released together, they create a long-lasting depolarization of the postsynaptic cell.

Key Concepts

Long-term Potentiation (LTP)

LTP is a long-lasting enhancement in signal transmission between two neurons that results from their synchronous stimulation. It is considered one of the major cellular mechanisms that underlies learning and memory, representing a form of synaptic plasticity where the strength of synaptic connections is modified over time.

NMDA Receptor Activation

NMDA receptors are a type of glutamate receptor that play a critical role in synaptic plasticity and memory function. Their activation requires both ligand binding and postsynaptic depolarization, which relieves a magnesium block. This unique property makes NMDA receptors key triggers in processes such as LTP, where they allow the influx of calcium ions that is essential for initiating intracellular signaling cascades.

Calcium Signaling

Calcium ions serve as a vital second messenger in neurons, linking receptor activation to long-term changes within the cell. The entry of calcium through NMDA receptors during synaptic activity activates various intracellular signaling pathways, which in turn can lead to synaptic modifications such as receptor trafficking and changes in gene expression, thereby contributing to the establishment of LTP.

AMPA Receptor Trafficking

AMPA receptors are another type of glutamate receptor involved in synaptic transmission. During LTP, an increase in the number and function of AMPA receptors at the postsynaptic membrane enhances synaptic strength. This receptor trafficking, or the insertion of more receptors into the membrane, is a crucial mechanism by which the efficacy of synaptic communication is augmented following activity-dependent signaling.

Transcript

00:01 Hello, everyone.

00:01 This is ricky, and today we're working on question number 10 from chapter 44.

00:06 And we'll be talking about long -term potentiation, or ltp.

00:11 And this question in particular emphasizes a coincidence detection in excitatory glutamate neurons.

00:30 And so there are two glutamate receptors that are important to keep in mind when we're talking about ltp in these types of excitatory neurons.

00:42 And those are ampa receptors and nmda receptors.

00:54 So they are both activate when bound to glutamate.

01:00 However, nmda receptors are plugged by magnesium in ions.

01:13 And nmda receptors also allow calcium influx, while amporeceptors are mostly sodium influx.

01:29 And so to open an nmda receptor, we need two things to happen simultaneously.

01:40 So opening receptors, we need glutamate to bind to the receptor.

01:53 And then we also need the membrane must be depolarized.

02:09 Because what we'll see happen is if this is our close -up of our cell membrane, and this is our nmda receptor, and here's our magnesium.

02:26 Plug.

02:30 So membrane and mda magnesium plus two.

02:44 When we depolarize the membrane, the inside of the membrane becomes more positive, or more positive charge builds up on the inside of the membrane.

02:59 And just for reference, this is extracellular...

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