What is the key question regarding activity-induced LTP and LTD?
Click to see answer
Does it lead to the formation and elimination of synaptic connections?
Click to see question
What is the key question regarding activity-induced LTP and LTD?
Does it lead to the formation and elimination of synaptic connections?
What must circuits in the nervous system do to act as associative memories?
Dynamically interleave storage of new patterns with recall of old patterns.
What is temporal summation?
The process where multiple stimuli are applied in quick succession to produce a stronger response.
What is the typical distance of the space between the pre and post synaptic membrane of a synapse?
10 - 15 nm.
What relationship is being questioned between functional plasticity and structural plasticity?
Does functional plasticity lead to structural plasticity?
What happens to AMPA receptors after LTP induction?
They move to spines.
Who postulated the cellular and circuit-level mechanisms for associative memory?
Paulsen and Moser.
What happens if stimuli are too far apart in time during temporal summation?
No summation occurs.
Which areas of the mammalian hippocampus are referenced in the study of associative memory?
Areas CA3 and CA1.
Which study discusses the movement of AMPA receptors after LTP induction?
Shi et al., Science 284: 1811 (11 Jun 1999).
What is the significance of the hippocampus in associative memory?
It provides mechanisms for storing and recalling patterns.
What is summation in the context of synaptic transmission?
The fusion or summation of effects when many presynaptic excitatory terminals are stimulated simultaneously or a single terminal is stimulated repeatedly.
What is spatial summation?
Occurs when two subliminal stimuli reach the synapse one after another from two different presynaptic terminals.
What is temporal summation?
The process where multiple stimuli are applied in close succession, leading to a cumulative effect.
What is the effect of an inhibitory postsynaptic potential (IPSP) on the postsynaptic membrane?
It hyperpolarizes the postsynaptic membrane.
What is the trigger zone in a neuron?
The area where the action potential (AP) is initiated.
What is temporal summation?
Occurs when two or more subliminal stimuli are applied one after another at quicker intervals from one presynaptic terminal repeatedly.
What is Long Term Potentiation (LTP)?
A process where changes occur in the postsynaptic neuron, similar to Post-Tetanic Potentiation (PTP).
What is the main excitatory neurotransmitter in the brain?
Glutamate.
Which ion channels are involved in hyperpolarizing the postsynaptic membrane during an IPSP?
Cl– channels.
What happens when stimuli are closer in time during temporal summation?
They can lead to summation of postsynaptic potentials, even if each individual stimulus is below the threshold.
What type of synapse is Golgi Type I?
Axodendritic and excitatory.
What does the trigger zone initiate?
An action potential (AP).
What is presynaptic facilitation?
It is the process where an excitatory interneuron increases neurotransmitter release from a presynaptic neuron.
What role do LTP and PTP play in the brain?
They are involved in the learning and memory processes.
What are the two classes of ligand-gated ion channels that mediate glutamate response?
NMDA receptors and AMPA/kainate receptors.
Which option correctly describes the mechanism of an IPSP?
Hyperpolarizes the postsynaptic membrane by opening Cl– channels.
What type of synapse is Golgi Type II?
Axosomatic and inhibitory.
What is the significance of being below threshold in temporal summation?
It indicates that while individual stimuli do not trigger an action potential, their cumulative effect may still approach the threshold.
What role does the excitatory interneuron play in presynaptic facilitation?
It causes increased Ca++ influx into the presynaptic terminal.
Why is the trigger zone important?
It is crucial for the propagation of electrical signals in neurons.
What does Hebb's Postulate state?
When an axon of cell A excites cell B repeatedly, a growth process occurs that increases A's efficiency in firing B.
In which part of the brain has LTP been studied in greater detail?
The hippocampus region.
Which receptors mediate most of the change in membrane potential?
AMPA receptors.
What is the relationship between Spine & Shaft and synaptic type?
Spine & Shaft is axodendritic and excitatory.
What is the result of increased Ca++ influx in the presynaptic terminal?
It leads to greater release of neurotransmitter substances.
What is habituation?
A decrease in response to certain stimuli that are not significant when applied repeatedly.
What can be studied in vitro from slices of the hippocampus?
The CA1 neurons using recording electrodes.
What processes in the adult brain are similar to activity-dependent developmental refinement of connections?
Learning and memory.
What is Post Tetanic Potentiation (PTP)?
A phenomenon where tetanic stimulation in the presynaptic neuron increases excitability to the postsynaptic membrane after a pause.
What is spatial summation?
The process where simultaneous input from two or more synapses contributes to reaching the threshold for action potential.
What happens to plasma membrane AMPA receptors during synaptic changes?
They are phosphorylated and become more active.
What is a synapse?
A junction between two neurons or a muscle where information is transmitted.
How does presynaptic facilitation affect the postsynaptic neuron?
It increases the excitability of the postsynaptic neuron.
What characterizes an axosomatic synapse?
It is not associated with shaft and spine and is inhibitory.
What is sensitization?
Prolonged occurrence of augmented postsynaptic response due to presynaptic facilitation.
In a sequence of synaptic transmission, which event occurs the earliest?
b. Opening of calcium channel in presynaptic neuron.
What happens during rapid, intense stimulation of presynaptic neurons?
It evokes action potentials in the postsynaptic neuron.
What is the resting potential?
The electrical charge difference across the neuronal membrane when the neuron is not actively firing.
What is required for spatial learning in the hippocampus?
Long-term potentiation (LTP).
What causes the increase in excitability in PTP?
An increase in Ca++ entry into the presynaptic neuron.
What happens when inputs from two synapses are above the threshold?
They can trigger an action potential due to spatial summation.
Is Cam KII the only relevant kinase in synaptic changes?
No, it is not the only relevant kinase.
What is the role of the presynaptic neuron?
It sends a message down its axon and across a synapse to another cell.
What mediates the changes leading to sensitization?
Calcium ions (Ca++), which affect adenylate cyclase and increase cAMP production.
What happens after the opening of calcium channels in presynaptic neurons?
a. Release of neurotransmitter from presynaptic neuron.
Which brain region is involved in fear conditioning and requires LTP?
Amygdala.
What does EPSP stand for?
Excitatory Postsynaptic Potential.
What is expected from the properties of synapses during stimulation?
Action potentials in the postsynaptic neuron.
What role does norepinephrine (NE) play in the brain?
It may cause either excitation or inhibition and is involved in arousal, dreaming, and mood.
What is the role of Acetylcholine at the neuromuscular junction (NMJ)?
It acts as an excitatory neurotransmitter by opening ligand-gated Na+ channels.
What type of stimulation leads to Post Tetanic Potentiation?
Tetanic stimulation.
What is the significance of simultaneous input in spatial summation?
It allows for the combined effects of multiple synaptic inputs to reach the threshold for neuronal firing.
What structural change may occur in dendrites during synaptic plasticity?
The dendrite may sprout new spines.
What is the function of the postsynaptic neuron?
It receives the message from the synapse.
What role does protein synthesis play in sensitization?
It is involved in the growth of pre- and postsynaptic neurons and their connections.
What is the role of voltage-gated sodium channels in synaptic transmission?
They open after calcium channels to propagate the action potential.
What is the function of an EPSP?
To depolarize the postsynaptic membrane, making it more likely to fire an action potential.
What accompanies LTP/LTD induction at synapses?
Structural changes.
What is synaptic plasticity?
The structural and functional changes in synapses due to repeated stimulation of neurons.
How does Acetylcholine function as an inhibitory neurotransmitter?
It acts via receptors linked to a G-protein.
What happens to the postsynaptic membrane after a pause following tetanic stimulation?
Its excitability increases.
What is the threshold in the context of synaptic input?
The minimum level of depolarization required to trigger an action potential.
What is necessary for long-lasting changes in synaptic plasticity?
Gene expression.
What types of cells can form synapses?
Buttons and an axon, dendrite, soma, muscle cells, or secretory cells of glands.
What causes an EPSP?
The opening of ligand-gated Na+ channels and the entry of Na+ ions into the postsynaptic neuron.
What is presynaptic facilitation?
A type of synaptic plasticity that enhances neurotransmitter release from the presynaptic neuron.
What behaviors is dopamine associated with?
Emotional response, addictive behavior, and pleasurable experiences.
What is the purpose of priming vesicles in neuronal endings?
To prepare neurotransmitters for release upon stimulation.
Which amino acids are known for their powerful excitatory effects in the CNS?
Glutamate and Aspartate.
How can sensitization be reinforced?
By additional pairing of a noxious stimulus with the initial stimulus.
What does IPSP stand for?
Inhibitory Postsynaptic Potential.
What are neurotrophins required for in the brain?
Developmental refinement of connections and LTP induction.
What type of change occurs presynaptically during synaptic plasticity?
Something happens presynaptically, though specifics are not detailed.
What is Neuropeptide Y known for?
It includes enkephalin, endorphin, and dynorphin, which are natural painkillers.
What is the characteristic of the cleft at a synapse?
It is a microscopic cleft where information is transmitted across at high speed.
What is a contributing factor to EPSP besides Na+ entry?
Closure of K+ channels can also contribute to the EPSP.
Where is serotonin concentrated in the brain?
In the raphe nucleus.
What occurs when neurotransmitters bind to receptors?
They initiate postsynaptic potentials.
What percentage of synapses in the brain are influenced by Glutamate and Aspartate?
They have a powerful excitatory effect in most of the CNS and half of the synapses in the brain.
What is the function of an IPSP?
To hyperpolarize the postsynaptic membrane, making it less likely to fire an action potential.
What example is given for neurotrophins' role in developmental refinement?
Ocular dominance segregation.
How much stronger is enkephalin compared to morphine?
200 times stronger.
What does post tetanic potentiation (PTP) refer to?
A form of synaptic plasticity that occurs after a high-frequency stimulation, leading to increased neurotransmitter release.
What type of current is associated with EPSP?
A depolarizing current.
What is the law of forward in synapses?
One way conduction.
What functions is serotonin thought to be involved in?
Sensory perception, body temperature regulation, control of mood, appetite, and sleep.
How do EPSPs and IPSPs affect neuronal firing?
EPSPs increase the likelihood of firing, while IPSPs decrease it.
What is the function of GABA and Glycine in the CNS?
They are important inhibitory neurotransmitters that cause IPSP by opening Cl- channels.
What role does Substance P play in the nervous system?
It transmits pain-related input from peripheral pain receptors to the CNS.
What is long term potentiation (LTP)?
A lasting increase in synaptic strength following high-frequency stimulation.
What causes an IPSP?
A hyperpolarizing current due to the influx of Cl- or the exit of K+ ions.
What is a characteristic delay in synaptic transmission called?
Synaptic delay.
What type of neurotransmitters are ATP, ADP, and AMP?
Excitatory neurotransmitters in both the CNS and PNS.
What is the significance of time in relation to EPSP and IPSP?
The timing of EPSPs and IPSPs influences the overall excitability of the neuron and its ability to reach the threshold for firing.
How does Diazepam (Valium) affect GABA?
It enhances the action of GABA.
How does enkephalin affect Substance P?
Enkephalin suppresses the release of Substance P and participates in pain inhibition.
What is habituation in the context of synaptic plasticity?
A decrease in response to a repeated, benign stimulus.
How does an IPSP affect membrane potential?
It causes the membrane potential to become more negative.
What is temporal summation?
The process where multiple stimuli are received in close succession, leading to a cumulative effect on the postsynaptic potential.
What does EPSP stand for?
Excitatory Postsynaptic Potential.
What phenomenon occurs when synapses become less effective after prolonged use?
Fatigue.
What is an Aoxaxonic Synapse?
A type of synapse where an axon connects to another axon.
What is sensitization in synaptic plasticity?
An increased response to a stimulus following a strong or noxious event.
What are co-transmitters?
Other chemicals secreted with neurotransmitters that help regulate neurotransmitter action.
What triggers the release of inhibitory neurotransmitters?
The hyperpolarizing current associated with IPSP.
What effect does EPSP have on the postsynaptic cell?
It encourages the firing of the postsynaptic cell.
What happens when stimuli are closer in time during temporal summation?
They can combine to exceed the threshold for action potential generation.
What are the two types of summation in synaptic transmission?
Spatial and Temporal.
What is an Axodendritic Synapse?
A synapse where an axon connects to a dendrite.
Give an example of a co-transmitter.
VIP with acetylcholine or Neuropeptide Y with norepinephrine.
How does EPSP increase the likelihood of firing in the postsynaptic cell?
By opening channels for Na+ ions, making the cell's interior more positive.
What is the significance of exceeding the threshold in temporal summation?
It triggers an action potential in the postsynaptic neuron.
What is the term for multiple signals converging onto a single neuron?
Convergence.
What is an Axosomatic Synapse?
A synapse where an axon connects to a cell body (soma).
What does IPSP stand for?
Inhibitory Postsynaptic Potential.
What is the threshold in the context of synaptic transmission?
The minimum level of stimulation required to trigger an action potential.
What is the process called when a single neuron sends signals to multiple neurons?
Divergence.
What is a Dendrodendritic Synapse?
A synapse where dendrites connect to other dendrites.
What effect does IPSP have on the postsynaptic cell?
It discourages the firing of the postsynaptic cell.
What is the term for the area of a synapse that can respond to sub-threshold stimuli?
Subliminal fringe.
What is an Electrical Synapse?
A type of synapse that allows direct electrical communication between neurons.
How does IPSP decrease the likelihood of firing in the postsynaptic cell?
By opening K+ and Cl- channels, making the cell's interior more negative.
What phenomenon occurs when the effect of one synaptic input is reduced by another?
Occlusion.
What is a Chemical Synapse?
A synapse that uses neurotransmitters to transmit signals between neurons.
What is required for the postsynaptic cell to fire when IPSP is present?
More excitatory impulses than usual.
What is an Excitatory Synapse?
A synapse that increases the likelihood of the postsynaptic neuron firing an action potential.
What initiates the synaptic transmission process?
The Action Potential (AP) reaching the axon terminal.
What is an Inhibitory Synapse?
A synapse that decreases the likelihood of the postsynaptic neuron firing an action potential.
What happens when the Action Potential reaches the axon terminal?
Opening of voltage-gated Ca²⁺ channels in the presynaptic membrane terminal.
What is a Conjoint Synapse?
A synapse that involves multiple types of synaptic connections.
What occurs after the opening of voltage-gated Ca²⁺ channels?
Influx of Ca²⁺ ions from the extracellular fluid (ECF) into the axon terminal.
What is released from vesicles in the axon terminal?
Acetylcholine (Ach).
What happens to Acetylcholine after its release?
It passes through the synaptic cleft.
What forms when Acetylcholine binds to its receptors?
The Acetylcholine-Receptor (Ach-R) complex.
What is the result of the formation of the Ach-R complex?
Opening of ligand-gated Na⁺ channels in the postsynaptic membrane and influx of Na⁺ ions from ECF.
What develops as a result of Na⁺ influx in the postsynaptic membrane?
Excitatory Postsynaptic Potential (EPSP).
What happens after the development of EPSP?
Opening of ligand-gated Na⁺ channels in the axon hillock.
What occurs after Na⁺ influx in the axon hillock?
Development of Action Potential (AP).
What is the final outcome of the synaptic transmission process?
Spread of Action Potential through the axon of the postsynaptic membrane.
