6.3.4 Excitation and Inhibition

• What does excitation in synaptic transmission refer to?

  Likelihood of action potential
• Inhibitory neurotransmitters lead to postsynaptic hyperpolarization
• What is the threshold potential in synaptic transmission?

  Level needed for action potential
• The balance of excitation and inhibition determines whether an action potential is generated.
• Match the neurotransmitter with its effects:

  Glutamate ↔️ Increases action potential likelihood

  GABA ↔️ Decreases action potential likelihood
• What happens to the postsynaptic neuron's membrane during excitation?

  It depolarizes
• Glutamate receptors allow both $\text{Na}^{ + }$ and $\text{Ca}^{2 + }$ ions to flow in.
• Excitatory neurotransmitters increase the likelihood of firing an action potential by depolarizing the postsynaptic neuron's membrane.
• Which ions are involved in the effects of glutamate?

  $\text{Na}^{ + }$ and $\text{Ca}^{2 + }$
• Steps leading to an action potential in synaptic transmission

  1️⃣ Excitatory neurotransmitters bind to receptors

  2️⃣ Postsynaptic neuron depolarizes

  3️⃣ Membrane potential reaches threshold

  4️⃣ Action potential is generated
• What is the effect of inhibition on the postsynaptic neuron's membrane?

  Hyperpolarization
• \text{GABA}</latex> binds to $\text{GABA}_{A}$ receptors, causing $\text{Cl}^{ - }$ ions to flow into the neuron, leading to hyperpolarization
• $\text{GABA}$ decreases the likelihood of an action potential.
• What is the primary effect of excitatory neurotransmitters on the postsynaptic neuron?

  Depolarization
• When $\text{Glutamate}$ binds to $\text{AMPA}$ receptors, $\text{Na}^{ + }$ and \text{Ca}^{2 + }</latex> ions flow into the neuron, causing depolarization
• What is the primary role of excitatory neurotransmitters in postsynaptic depolarization?

  Increase action potential likelihood
• The neurotransmitter Glutamate binds to AMPA and NMDA receptors.
• Which ions flow into the neuron when Glutamate binds to AMPA and NMDA receptors?

  \text{Na}^{ + }</latex> and $\text{Ca}^{2 + }$
• Excitation in synaptic transmission depolarizes the postsynaptic neuron's membrane.
• What is the primary effect of inhibition in synaptic transmission?

  Hyperpolarization of the membrane
• The neurotransmitter GABA binds to $\text{GABA}_{A}$ receptors.
• Which ion flows into the neuron when GABA binds to $\text{GABA}_{A}$ receptors?


  $\text{Cl}^{ - }$
• Inhibition in synaptic transmission hyperpolarizes the postsynaptic neuron's membrane.
• Which ion flows into the neuron when GABA binds to $\text{GABA}_{A}$ receptors?


  $\text{Cl}^{ - }$
• Inhibition in synaptic transmission occurs through hyperpolarization
• GABA binding to $\text{GABA}_{A}$ receptors makes the inside of the neuron more negative.
• What is the effect of excitation on the likelihood of an action potential?

  Increases likelihood
• Steps leading to postsynaptic depolarization

  1️⃣ Presynaptic neuron releases neurotransmitters

  2️⃣ Neurotransmitters bind to receptors

  3️⃣ Ion channels open, allowing positive ions to enter

  4️⃣ Depolarization occurs, increasing action potential likelihood
• \text{Glutamate}</latex> binds to $\text{AMPA}$ receptors, allowing $\text{Na}^{ + }$ to flow into the neuron, causing depolarization
• Inhibitory neurotransmitters reduce the likelihood of an action potential.
• Which ions exit the neuron during hyperpolarization caused by GABA?

  $\text{K}^{ + }$
• Hyperpolarization makes it more difficult for the neuron to reach the threshold for an action potential
• Steps leading to postsynaptic depolarization by excitatory neurotransmitters

  1️⃣ Presynaptic neuron releases neurotransmitters

  2️⃣ Neurotransmitters bind to receptors

  3️⃣ Ion channels open, allowing positive ions to enter

  4️⃣ Depolarization occurs, increasing action potential likelihood
• What is the effect of $\text{Glutamate}$ binding to $\text{AMPA}$ receptors on the postsynaptic neuron?


  Depolarization
• The efflux of $\text{K}^{ + }$ ions leads to hyperpolarization of the postsynaptic neuron.
• What happens when glutamate binds to AMPA receptors?

  $\text{Na}^{ + }$ ions flow in
• Inhibitory neurotransmitters hyperpolarize the postsynaptic neuron.
• What ion flows into the postsynaptic neuron when GABA binds to $\text{GABA}_{A}$ receptors?


  \text{Cl}^{ - }</latex>
• Match the neurotransmitter type with its effect on the postsynaptic neuron:

  Excitatory ↔️ Increases likelihood of action potential

  Inhibitory ↔️ Decreases likelihood of action potential
• Steps of temporal summation

  1️⃣ Rapid succession of potentials at one synapse

  2️⃣ Combined effect exceeds threshold

  3️⃣ Action potential is triggered