Lecture 16 - Cellular Learning and Memory

Question 1

What percentage of the population is affected by insomnia regularly?

Answer 1

Insomnia affects 9% of the population regularly.

Question 1

What are some potential consequences of untreated insomnia?

Answer 1

Untreated insomnia can lead to fatigue, concentration issues, mood disturbances, and increased health risks like heart disease.

Question 2

What is Fatal Familial Insomnia?

Answer 2

Fatal Familial Insomnia is a rare, progressive insomnia due to neurodegeneration, leading to hallucinations, delirium, coma, and eventual death.

Question 3

Which brain regions are primarily affected in Fatal Familial Insomnia?

Answer 3

The thalamus, hypothalamus, and brainstem are primarily affected.

Question 4

What are non-REM parasomnias?

Answer 4

Non-REM parasomnias are sleep disorders that occur during non-REM sleep or sleep-wake transitions, such as sleepwalking and sleep talking.

Question 5

What are sleep terrors, and who are they more common in?

Answer 5

Sleep terrors involve sudden waking with intense fear and panic behaviors, with no memory of the episode, and are more common in individuals with PTSD.

Question 6

What is REM Sleep Behavior Disorder (RBD)?

Answer 6

RBD is characterized by the absence of muscle paralysis during REM sleep, allowing individuals to act out their dreams, potentially causing self-harm or injury to others.

Question 7

How is REM Sleep Behavior Disorder associated with neurodegenerative diseases?

Answer 7

RBD is often linked to conditions like Parkinson’s disease and may have a genetic component.

Question 8

What is the definition of learning?

Answer 8

Learning is the process of acquiring new information.

Question 9

How is memory defined?

Answer 9

Memory is the ability to store and retrieve information.

Question 10

What are the two types of memory?

Answer 10

The two types of memory are explicit memory, which is consciously recalled (e.g., facts and events), and implicit memory, which is automatic and unconscious (e.g., skills and habits).

Question 11

What is neuronal plasticity?

Answer 11

Neuronal plasticity is the brain’s ability to adapt and change in response to experiences.

Question 12

What does intrinsic excitability refer to?

Answer 12

Intrinsic excitability refers to how responsive a neuron is to incoming signals, measured by the number of action potentials it generates.

Question 13

What is synaptic strength?

Answer 13

Synaptic strength refers to the strength of connections between neurons, which can be altered through learning.

Question 14

What are presynaptic changes in synaptic plasticity?

Answer 14

Presynaptic changes involve modifications in neurotransmitter release, including the number of vesicles, neurotransmitter quantity, and release frequency.

Question 15

What is habituation in the context of non-associative learning?

Answer 15

Habituation is the decreased response to a repeated, harmless stimulus.

Question 16

Provide an example of habituation of reflexes.

Answer 16

An example is the sea slug (Aplysia) showing reduced gill withdrawal reflex after repeated harmless touches.

Question 17

What occurs during long-term habituation?

Answer 17

Long-term habituation involves structural changes, such as physical growth in synapses, where the presynaptic side may store more vesicles and the postsynaptic side may develop more receptors.

Question 18

What is Long-Term Potentiation (LTP)?

Answer 18

Long-Term Potentiation (LTP) is a long-lasting increase in synaptic strength, typically induced by high-frequency stimulation (100 Hz).

Question 19

What is Long-Term Depression (LTD)?

Answer 19

Long-Term Depression (LTD) is a long-lasting decrease in synaptic strength, typically induced by low-frequency stimulation (1 Hz).

Question 20

How does high-frequency stimulation induce LTP?

Answer 20

High-frequency stimulation increases synaptic strength by causing action potentials in the postsynaptic neuron, leading to the insertion of more AMPA receptors into the postsynaptic membrane.

Question 21

How does low-frequency stimulation induce LTD?

Answer 21

Low-frequency stimulation weakens synaptic strength due to insufficient excitation of the postsynaptic neuron, which leads to the removal of AMPA receptors from the postsynaptic membrane.

Question 22

What role do NMDA receptors play in LTP and LTD?

Answer 22

NMDA receptors allow calcium entry into the postsynaptic cell. In LTP, a large and brief calcium influx activates signaling pathways that enhance synaptic strength. In LTD, a smaller and sustained calcium influx activates protein phosphatases that weaken synaptic strength.

Question 23

What are AMPA receptors and how do they contribute to synaptic plasticity?

Answer 23

AMPA receptors mediate fast synaptic transmission by allowing sodium ions to enter the postsynaptic neuron. In LTP, more AMPA receptors are inserted into the postsynaptic membrane, strengthening the synapse. In LTD, AMPA receptors are removed, weakening synaptic transmission.

Question 24

In the experiment setup, what is the difference between high-frequency and low-frequency stimulation?

Answer 24

High-frequency stimulation (100 Hz) strengthens synaptic connections by promoting LTP, while low-frequency stimulation (1 Hz) weakens synaptic connections by inducing LTD.

Question 25

How can the hypothesis about synaptic strengthening being dependent on membrane potential or action potentials be tested?

Answer 25

The hypothesis can be tested by stimulating neurons at high or low frequencies and observing whether the changes in synaptic strength are more dependent on membrane potential or the actual firing of action potentials in the postsynaptic neuron.

Question 26

If a scientist observes an increase in neurotransmitter release from the presynaptic neuron and more receptors on the postsynaptic membrane, which process are they likely observing: LTP or LTD?

Answer 26

They are likely observing LTP, as it involves both the increase in neurotransmitter release and the insertion of more receptors on the postsynaptic membrane.

Question 27

In a real-life scenario, if someone undergoes repeated exposure to a rewarding stimulus, what type of synaptic plasticity might occur?

Answer 27

Long-Term Potentiation (LTP) might occur, as repeated exposure to a rewarding stimulus could lead to increased synaptic strength and enhanced neural responses to the stimulus.

Question 28

Imagine a scenario where someone experiences a repeated failure to respond to a stimulus despite repeated exposure. What type of synaptic plasticity might this result in?

Answer 28

Long-Term Depression (LTD) might occur, as the lack of sufficient excitation from the stimulus could weaken synaptic strength over time.

Question 29

What is the role of calcium influx through NMDA receptors in the induction of LTP?

Answer 29

Calcium influx through NMDA receptors activates intracellular signaling pathways like CaMKII and PKC, which lead to the insertion of more AMPA receptors into the postsynaptic membrane, strengthening the synapse.

Question 30

How would the removal of AMPA receptors from the postsynaptic membrane affect synaptic strength?

Answer 30

The removal of AMPA receptors weakens synaptic strength by reducing the postsynaptic response to neurotransmitter release, contributing to LTD.

Question 31

What does high-frequency stimulation (100 Hz) induce in the postsynaptic neuron?

Answer 31

High-frequency stimulation induces depolarization of the postsynaptic neuron, which relieves the NMDA receptor block and allows calcium entry, triggering long-term potentiation (LTP).

Question 32

What is the effect of high-frequency stimulation on synaptic strength?

Answer 32

High-frequency stimulation strengthens the synapse by inserting additional AMPA receptors into the postsynaptic membrane, making the synapse more responsive to glutamate.

Question 33

How does low-frequency stimulation (1 Hz) affect synaptic strength?

Answer 33

Low-frequency stimulation leads to a smaller calcium influx through NMDA receptors, which activates protein phosphatases and results in the removal of AMPA receptors from the postsynaptic membrane, leading to long-term depression (LTD).

Question 34

What is long-term potentiation (LTP)?

Answer 34

Long-term potentiation (LTP) is the process by which repeated high-frequency stimulation strengthens synapses, making them more responsive to future stimuli.

Question 35

What is long-term depression (LTD)?

Answer 35

Long-term depression (LTD) is the process by which low-frequency stimulation weakens synapses by removing AMPA receptors from the postsynaptic membrane.

Question 36

How do NMDA receptors contribute to synaptic plasticity?

Answer 36

NMDA receptors act as coincidence detectors, requiring both glutamate binding and membrane depolarization to allow calcium ions to flow into the neuron, which strengthens synaptic connections.

Question 37

What is classical conditioning?

Answer 37

Classical conditioning is a learning process in which an animal learns to associate a neutral stimulus with a significant event, leading to a conditioned response (e.g., blinking when a tone is heard before a puff of air).

Question 38

How does classical conditioning differ from reflexive responses?

Answer 38

Reflexive responses are automatic reactions to stimuli that do not require learning, while classical conditioning involves learning associations between stimuli over time, leading to a conditioned response.

Question 39

In classical conditioning, how does a tone eventually trigger a blink in an animal?

Answer 39

Through repeated pairings of the tone with a puff of air, the synaptic connections between the tone-detecting neurons and the blink-controlling neurons strengthen, eventually causing the tone to trigger the blink response.

Question 40

What role do NMDA receptors play in classical conditioning?

Answer 40

NMDA receptors allow the synaptic connections between tone-detecting neurons and blink motor neurons to strengthen during repeated pairings, contributing to the learning process.

Question 41

What does it mean for NMDA receptors to be “coincidence detectors”?

Answer 41

NMDA receptors are called coincidence detectors because they require both glutamate binding to the receptor and the depolarization of the neuron’s membrane (removal of the magnesium block) to allow calcium influx.

Question 42

How does calcium influx through NMDA receptors strengthen synaptic connections?

Answer 42

Calcium influx triggers intracellular processes that strengthen the synapse, making the connection more likely to fire in the future when the same stimulus is present.

Question 43

Why is synaptic plasticity important for learning and memory?

Answer 43

Synaptic plasticity allows synapses to change in response to activity, strengthening or weakening over time, which is crucial for forming and retaining memories.

Question 44

How can researchers study memory by manipulating NMDA receptors?

Answer 44

By removing NMDA receptors, researchers can observe whether a memory disappears, helping to identify the role of specific synapses and receptors in memory formation.

Question 45

How are memories stored in the brain?

Answer 45

Memories are stored in the strength of synapses; stronger synapses help retain learned responses.

Question 46

Why is it difficult to pinpoint a specific location for memory storage in the brain?

Answer 46

Memories are likely distributed across multiple synapses and neurons, making them part of complex networks, which complicates isolating a single memory location.

Question 47

What might happen if NMDA receptors are removed from an animal’s brain?

Answer 47

If NMDA receptors are removed, the animal may lose the ability to form certain types of memories, demonstrating the critical role these receptors play in memory formation.

Question 48

Imagine a person is exposed to a repeated tone before a puff of air. Over time, they begin blinking when they hear the tone alone. What process is responsible for this change?

Answer 48

The process responsible for this change is classical conditioning, where the animal learns to associate the tone (neutral stimulus) with the puff of air (significant event), leading to the conditioned blink response.

Question 49

What is Associative Long-Term Potentiation (Associative LTP)?

Answer 49

Associative Long-Term Potentiation (Associative LTP) is a process where weak synapses, activated simultaneously with stronger synapses, become stronger. This process helps the brain “learn” associations between stimuli.

Question 50

How does Associative LTP strengthen weak synapses?

Answer 50

When a weak synapse and a strong synapse are activated together, the weak synapse strengthens and eventually becomes capable of independently triggering a neuron’s action potential.

Question 51

What is Hebb’s Rule?

Answer 51

Hebb’s Rule, or “Fire together, wire together,” explains that when two neurons fire together, their synaptic connection becomes stronger, making future communication easier. This mechanism is central to learning and memory.

Question 52

How does Hebb’s Rule relate to learning?

Answer 52

Hebb’s Rule suggests that learning strengthens synaptic connections between neurons that fire simultaneously, improving their future communication and facilitating memory formation.

Question 53

What is the significance of the hippocampus in memory?

Answer 53

The hippocampus is essential for forming long-term memories, especially episodic memories, which involve recalling specific events. Damage to the hippocampus impairs the ability to form lasting, conscious memories.

Question 54

What role does the hippocampus play in learning?

Answer 54

The hippocampus plays a critical role in memory formation and the consolidation of long-term memories, particularly those formed from individual events.

Question 55

How are brain slice preparations used in studying LTP?

Answer 55

Brain slice preparations allow researchers to stimulate neurons in isolated brain tissue, enabling them to observe how synapses strengthen over time and study mechanisms of learning and memory, particularly in the hippocampus.

Question 56

What happens to synaptic strength with different patterns of stimulation?

Answer 56

Synaptic strength can increase or decrease depending on the patterns of stimulation. Strong and weak stimulation patterns are used in research to understand how synapses adapt and change in response to learning.

Question 57

How does paired stimulation contribute to Associative LTP?

Answer 57

Paired stimulation, where weak and strong stimuli are presented together repeatedly, strengthens the weak synapse, enabling it to trigger an action potential independently, demonstrating synaptic connection reinforcement.

Question 58

What role do NMDA receptors play in Associative LTP?

Answer 58

NMDA receptors facilitate Associative LTP by allowing calcium ions to enter the neuron when it is depolarized, triggering changes that strengthen the synapse and improve future signaling.

Question 59

How do dendritic spikes influence synaptic strength?

Answer 59

Dendritic spikes occur when a neuron is strongly stimulated, causing depolarization to travel through the dendrites. This depolarization can influence nearby synapses, strengthening them through calcium influx via NMDA receptors.

Question 60

What is synapse-specific strengthening?

Answer 60

Synapse-specific strengthening ensures that only the synapses involved in paired stimulation are strengthened, making the connection between neurons more efficient for future signaling, without affecting unrelated synapses.

Question 61

What would happen if paired stimulation didn’t occur during LTP?

Answer 61

Without paired stimulation, the weak synapse would not strengthen, and the learning process would be less efficient, as synaptic connections would not be optimized for future communication.