16.22: Postsynaptic Potential (PSP)
Postsynaptic potential (PSP) refers to a change in the electrical potential of a neuron when neurotransmitters released by presynaptic neurons bind to postsynaptic receptors. This potential can either be excitatory, leading to depolarization and ultimately action potential generation, or inhibitory, leading to hyperpolarization and suppression of the postsynaptic neuron.
There are two types of receptors: ionotropic and metabotropic.
The ionotropic receptor is the membrane protein that has an ion channel and a neurotransmitter binding site to facilitate the ion flow in or out of the postsynaptic neuron and alter its membrane potential. A metabotropic receptor has a binding site but lacks the ion channel and acts through G protein.
The PSP generated by ionotropic receptors is either excitatory or inhibitory, depending on the type of ion moving through the channel. For example, an influx of positive ions (typically sodium) will cause depolarization and create an excitatory PSP, while an efflux of positive ions (like potassium) will produce a hyperpolarizing response due to increased negativity in the neuron, forming an inhibitory PSP.
An example of excitatory postsynaptic potential (EPSP) is found in the synapses of neurons in the central nervous system, where neurotransmitters such as acetylcholine, glutamate, and GABA are released to cause depolarization of the postsynaptic membrane and, ultimately, an action potential that propagates down the axon to its target cell. Inhibitory postsynaptic potentials (IPSPs) occur when inhibitory neurotransmitters such as glycine or GABA are released from a presynaptic neuron and cause hyperpolarization on the postsynaptic neuron, making it less likely for an action potential to be generated.
The PSP plays an important role in the functioning of neural circuits, allowing neurons to communicate with each other and ultimately coordinating the activity of a large network of neurons. PSPs help shape and modulate the output of a neuron in response to its inputs and are important for learning, memory formation, and information processing. In addition, PSPs are used as a readout measure in neuroscience studies, providing valuable insights into neural function. PSPs are essential for intercellular communication within the nervous system, allowing it to process and respond to external stimuli in an appropriate manner. By studying how postsynaptic potentials work at the cellular level, we can gain a better understanding of how neuronal networks operate to form complex behaviors.
Postsynaptic potentials are essential for information processing in the nervous system, and thus, it is important to understand how they work in order to better understand normal neurological functioning and diseases such as epilepsy or Parkinson's disease. By studying postsynaptic potentials, researchers can get a better insight into how neurons communicate with each other, allowing us to develop more effective treatments for these conditions.
