Chapter 12 - Section 12.6 - Study Guide - Assess Your Learning Outcomes - Page 471: 2

Excitatory Postsynaptic Potentials (EPSPs) and Inhibitory Postsynaptic Potentials (IPSPs) are types of electrical changes in the membrane potential of a postsynaptic neuron that result from the activation of synapses. These potentials play a critical role in determining whether a neuron will generate an action potential (nerve impulse) and transmit information to other neurons. Here's the meaning and distinction between EPSPs and IPSPs: 1. Excitatory Postsynaptic Potential (EPSP): - Meaning: An EPSP is a temporary, localized depolarization of the postsynaptic neuron's membrane potential. - Mechanism: EPSPs are typically caused by the release of neurotransmitters (e.g., glutamate) from presynaptic neurons that bind to receptors on the postsynaptic membrane. This binding opens ion channels, allowing positively charged ions (usually sodium, Na+) to flow into the neuron. - Effect: EPSPs make the postsynaptic neuron's membrane potential less negative (closer to the threshold for firing an action potential). They increase the likelihood that the neuron will reach its action potential threshold and generate an action potential, thereby transmitting an excitatory signal. 2. Inhibitory Postsynaptic Potential (IPSP): - Meaning: An IPSP is a temporary, localized hyperpolarization of the postsynaptic neuron's membrane potential. - Mechanism: IPSPs are typically caused by the release of neurotransmitters (e.g., GABA or glycine) from presynaptic neurons that bind to receptors on the postsynaptic membrane. This binding opens ion channels, allowing negatively charged ions (usually chloride, Cl-) to enter or positively charged ions (potassium, K+) to leave the neuron. - Effect: IPSPs make the postsynaptic neuron's membrane potential more negative (further away from the threshold for firing an action potential). They decrease the likelihood that the neuron will reach its action potential threshold, preventing it from firing and transmitting an inhibitory signal. In summary, EPSPs and IPSPs are two types of postsynaptic potentials that influence the excitability of a neuron. EPSPs make it more likely for a neuron to fire an action potential and transmit an excitatory signal, while IPSPs make it less likely for a neuron to fire an action potential and transmit an inhibitory signal. The balance between these excitatory and inhibitory inputs determines whether a neuron will generate an action potential and, consequently, the flow of information in neural circuits.

Excitatory Postsynaptic Potentials (EPSPs) and Inhibitory Postsynaptic Potentials (IPSPs) are types of electrical changes in the membrane potential of a postsynaptic neuron that result from the activation of synapses. These potentials play a critical role in determining whether a neuron will generate an action potential (nerve impulse) and transmit information to other neurons. Here's the meaning and distinction between EPSPs and IPSPs: 1. Excitatory Postsynaptic Potential (EPSP): - Meaning: An EPSP is a temporary, localized depolarization of the postsynaptic neuron's membrane potential. - Mechanism: EPSPs are typically caused by the release of neurotransmitters (e.g., glutamate) from presynaptic neurons that bind to receptors on the postsynaptic membrane. This binding opens ion channels, allowing positively charged ions (usually sodium, Na+) to flow into the neuron. - Effect: EPSPs make the postsynaptic neuron's membrane potential less negative (closer to the threshold for firing an action potential). They increase the likelihood that the neuron will reach its action potential threshold and generate an action potential, thereby transmitting an excitatory signal. 2. Inhibitory Postsynaptic Potential (IPSP): - Meaning: An IPSP is a temporary, localized hyperpolarization of the postsynaptic neuron's membrane potential. - Mechanism: IPSPs are typically caused by the release of neurotransmitters (e.g., GABA or glycine) from presynaptic neurons that bind to receptors on the postsynaptic membrane. This binding opens ion channels, allowing negatively charged ions (usually chloride, Cl-) to enter or positively charged ions (potassium, K+) to leave the neuron. - Effect: IPSPs make the postsynaptic neuron's membrane potential more negative (further away from the threshold for firing an action potential). They decrease the likelihood that the neuron will reach its action potential threshold, preventing it from firing and transmitting an inhibitory signal. In summary, EPSPs and IPSPs are two types of postsynaptic potentials that influence the excitability of a neuron. EPSPs make it more likely for a neuron to fire an action potential and transmit an excitatory signal, while IPSPs make it less likely for a neuron to fire an action potential and transmit an inhibitory signal. The balance between these excitatory and inhibitory inputs determines whether a neuron will generate an action potential and, consequently, the flow of information in neural circuits.