Excitatory postsynaptic potentials

Definition

Excitatory postsynaptic potentials (EPSPs) are changes in the membrane potential of a postsynaptic neuron that make it more likely to fire an action potential. This occurs when neurotransmitters bind to receptors on the postsynaptic membrane, leading to the influx of positively charged ions, such as sodium (Na+), which depolarizes the neuron. EPSPs play a crucial role in neural communication and are fundamental for information processing within neural networks, affecting how signals are integrated and how effectively neurons communicate with each other.

5 Must Know Facts For Your Next Test

1. EPSPs are graded potentials, meaning their amplitude can vary depending on the amount of neurotransmitter released and the number of receptors activated.
2. The summation of multiple EPSPs can lead to reaching the threshold potential, resulting in an action potential in the postsynaptic neuron.
3. EPSPs can be temporal or spatial; temporal summation occurs when multiple EPSPs arrive at a single neuron in quick succession, while spatial summation involves EPSPs from multiple neurons simultaneously.
4. The decay of EPSPs over time and distance is important for determining how signals are processed within neural networks.
5. Calcium ions (Ca2+) may also play a role in facilitating neurotransmitter release at synapses, indirectly influencing the generation of EPSPs.

Review Questions

• How do excitatory postsynaptic potentials contribute to the overall function of neural networks?
  • Excitatory postsynaptic potentials are crucial for the functioning of neural networks because they enhance the likelihood that a postsynaptic neuron will fire an action potential. By facilitating communication between neurons, EPSPs allow for the integration of incoming signals, enabling complex processing and response to stimuli. In networks, this means that multiple excitatory inputs can converge and influence decision-making processes, learning, and memory.
• Discuss the difference between excitatory postsynaptic potentials and inhibitory postsynaptic potentials regarding their roles in neuronal signaling.
  • Excitatory postsynaptic potentials increase the chances of a neuron firing by depolarizing its membrane potential, while inhibitory postsynaptic potentials decrease this likelihood by hyperpolarizing it. This balance between excitation and inhibition is essential for proper neuronal signaling and information processing. Together, these two types of potentials create a dynamic environment where neurons can finely tune their responses to various stimuli based on their excitatory and inhibitory inputs.
• Evaluate the significance of EPSPs in understanding neurological disorders related to synaptic transmission.
  • EPSPs are significant for understanding neurological disorders because abnormalities in their generation or integration can lead to conditions such as epilepsy or depression. In epilepsy, excessive excitatory activity can cause seizures, while in depression, altered synaptic transmission may impair normal signaling pathways. By studying EPSPs, researchers can gain insights into how these disorders disrupt normal brain function and explore potential therapeutic targets for restoring balance within neural circuits.

Related terms

action potential:

A rapid and temporary change in the membrane potential of a neuron, allowing for the transmission of electrical signals along the axon.

inhibitory postsynaptic potentials:

Changes in the membrane potential that make a postsynaptic neuron less likely to fire an action potential, typically due to the influx of negatively charged ions.

neurotransmitter: Chemical messengers released from presynaptic neurons that transmit signals across synapses to bind to receptors on postsynaptic neurons.