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Psyc 211 > Lecture 16- Learning And Memory Prt 1 > Flashcards

Lecture 16- Learning And Memory Prt 1 Flashcards

1
Q

What is learning?

A

The process by which some experiences change our nervous system, which in turn changes our behaviour.

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2
Q

What are memories?

A

They are the changes effectuated in our nervous system from different experiences.

Memories are transient or durable, explicit or implicit, personal or impersonal.

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3
Q

What is the process of accessing memories called

A

Memory retrieval

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4
Q

What does it mean to say that the brain is plastic?

A

It means that it is easily changed, easily molded to take any shape. It’s constantly changing in response to the environment.

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5
Q

What is neuronal plasticity?

A

It’s the ability of the nervous system to change and adapt. It’s physical changes in the brain. It’s the cellular basis of long-term memory.

(Ex: a protein changes place or there are more proteins in one place)

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6
Q

What is the intrinsic excitability?

A

It’s the number of axon potentials that neurons exhibit in response to an influx of positive current.

The more there are leak channels and gated channels, the more a neuron has intrinsic excitability.

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7
Q

What is the synaptic strength?

A

It’s the amount of positive (or negative) current that enters the postsynaptic neuron when a presynaptic cell has an action potential

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8
Q

What is synaptic plasticity?

A

It’s the change in the strength of the synaptic connection between two neurons (presynaptic and postsynaptic)

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9
Q

Where is long-term memory probably store?

A
  • Intrinsic excitability
  • Synaptic strenght
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10
Q

How is intrinsic excitability determined?

A

By the type and number of ion channels (leak channels and voltage-gated channels) expressed by neurons.

With more ion channels, a neuron has more action potentials or if there is less potassium leak channel, neuron becomes excitable quicker

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11
Q

What are enduring changes in synaptic strength referred to?

A
  • Long term potentiation (LTP)
    ————- If neuron becomes stronger

-Long term depression (LTD)
————- If neuron becomes weaker

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12
Q

What probably changed in a cell if sending a small amount of energy to a cell creates a bigger subthreshold EPSP after LTP induction?

A

The synaptic plasticity (the strength of the neuron)

The neuron is probably stronger and hence fires quicker

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13
Q

What are some examples of things that could have changed in a neuron to increase the synaptic plasticity?

A
  • increase in amount of voltage-gated calcium channels on the presynaptic membrane —> more vesicles released following an action potential
  • increase in amount of neurotransmitter receptors which influences the sensitivity of the postsynaptic cell to neurotransmitters
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14
Q

What is an aplysia?

A

-invertebrate sea slug with simple nervous system.
-has a large gill for respiration
-has a siphon that expels water

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15
Q

What happens if the siphon of the aplysia is touched?

A
  • it will withdraw reflexively.
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16
Q

What happens if the gill of the aplysia is touched lightly over and over again?

A
  • the magnitude of the reflex will reduce until the Aplysia completely ignores the stimulus
  • it learns that this stimulus is harmless and learns to ignore it
    -ex of habituation
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17
Q

What is habituation?

A

The reduced physiological or behavioural responding to a repeated stimulus

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18
Q

What is sensitization?

A

It’s the increased sensitivity to a stimulus

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19
Q

In the aplysia, if you touch the gill the 18th time compare to the 1st time, does it depolarizes the same amount?

A

YES

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20
Q

What are the effects of continued slight touch on the siphon of the aplysia?

A
  • it still depolarizes the same amount
  • Its excitability is reduced. This produces fewer action potentials
  • the synaptic connection is not weakened between the sensory and motor neurons
  • the motor neurons still as excitable.
  • the gill is still as sensitive to an action potential in the motor neuron as before
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21
Q

What are brain slices used for?

A
  • we slice parts of the brain of animals to study it under the microscope while it is still alive.
  • Cell excitability and synaptic strength can be measured this way
    -We can still excite neurons even if they are cut and no longer connected to the rest of the brain
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22
Q

What happens fo we block all synaptic activity?

A

The cells will express tons of neurotransmitter receptors. They get desperate to receive any kind of input and will make their chances higher of detecting any neurotransmitter. Neurons really adapt to the environment to bring the cell back into a healthy treshold.

23
Q

Why are some synapses really big and others very small?

A

We think it’s because the bigger ones are activated very often.

24
Q

Explain the deep neural network.

A

It is a neural net used in artificial intelligence for pattern recognition. It is made with an input and output layer as well as many hidden layers.

25
Q

What do the deep neural nets have to recognize the patterns?

A
  • Structure: number of nodes and layers as well as how each node gets activated
  • Objective function: the goal we want to give it
  • Learning function: method of adjusting the strength of each connection to better achieve the objective function
26
Q

What is long-term potentiation? (LTP)

A
  • it’s an increase in the strength of the connection between two neurons
    -increase in synaptic strength.
    -often initiated on the postsynaptic side (increase in neurotransmitter receptors)
27
Q

How is long-term potentiation (LPT) achieved by researchers?

A

-Repeated high frequency stimulation of the inputs to a neuron
-100 hz (100 times in 1 second), then wait a couple seconds
-repeated 4 times

28
Q

What is long-term depression (LTD)?

A
  • decrease in the strength of the connection between two neurons
    -decrease in synaptic strength
  • often initiated on the postsynaptic side (less neurotransmitter receptors)
  • but sometimes caused by less calcium influx per action potential (presynaptic —> number of neurotransmitter released decreased)
29
Q

How is long-term depression caused by researchers?

A
  • Persistent low frequency stimulation of the inputs to a quiet neuron.
    -1 hz stimulation for 10 minutes
30
Q

What is the difference between the occurrence of LTP or LTD?

A
  • its is determined by the number of times the synapse was activated combined with whether the postsynaptic neuron fired at those times
    -LTP —> the release of the transmitter has to be correlated with the depolarization of the postsynaptic cell which normally causes an action potential
    -LTD —> low frequency stimulation is not enough on its own to get the postsynaptic neuron to spike and create an action potential.
31
Q

How to create long term potentiation?

A
  • to strengthen a cell, you just have to stimulate the synapse of a cell while depolarizing the cell body.

-to weaken the cell, you stimulate the synapse without depolarizing the cell body.

32
Q

What is the NMDA receptor?

A
  • the coincidence detector
  • it is a glutamate receptor
    -when glutamate binds, it opens the pore of this receptor.
  • positive ions try to enter the cell
  • ## if the cell has a resting potential, mg+2 will try to enter but will clog the pore of the receptor.
33
Q

How to stop the mg+2 to stop clogging the NMDA receptor?

A
  • the cell membrane has to be depolarized.
    Mg+2 is no longer compelled to go in and calcium ions can come in the cell.
34
Q

By which two things is the NMDA receptor gated?

A
  • glutamate —> glutamate has to bind to the receptor in order for it to open
  • the membrane potential —> if the membrane is at resting potential of -40 mV and below, mg+2 will block the receptor and ca+2 will not be able to enter the cell. If the membrane is depolarized, mg+2 will no longer be compelled to enter the cell and the ca+2 will be able to enter the cell
35
Q

Why are NMDA receptors important in the field of neuroscience?

A
  • they are involved in every singe glutamate synapse in the brain
  • they play a large part in learning and memory
  • by controlling how much calcium gets in, this is the signal that determines whether synapses should become stronger or weaker
36
Q

Which two receptors do glutamate synapse have in the brain?

A
  • AMPA receptors
  • NMDA receptors
37
Q

What does the AMPA receptor do?

A

It’s a glutamate receptor.
It mediates most excitatory fast synaptic currents in the brain.
- ionotropic upon glutamate binding
- lets in sodium that depolarizes neuron

38
Q

How do the NMDA receptors strengthen the synapse and the neuron?

A
  • NMDA and AMPA are right next to each other. They both open with glutamate binding but NMDA is blocked by the mg+2.
  • NMDA will let calcium in only when the cell is about to spike or already spiking. The flow of calcium will send a signal to either strengthen or weaken the synapse.
  • current through the NMDA will directly make more AMPA receptors or less to either strengthen or weaken the synapse
39
Q

What is the CaMKII?

A
  • a key enzyme heavily expressed in neurons, dendrites, etc.
  • it is activated by calcium coming through the NMDA receptor
  • plays a role in the intracellular signalling cascade that establishes long term potentiation —> increasing the number of postsynaptic AMPA receptors
40
Q

What causes the growth of dentritic spines in synapses?

A
  • Long-term potentiation
41
Q

Which molecule can act as a retrogade messenger to promote LTP?

A

-Nitric oxide

42
Q

Can LTP also be expressed through changes in the presynaptic side of things?

A

-yes, but the postsynaptic neurons often initiate the process
-nitric oxide is released from postsynaptic membrane and is detected by the presynaptic membrane

43
Q

Can a 1000 Hz tone make you blink?

A
  • yes, the neuron in the auditory system is connected to blinking, but the synapse is very weak
  • synapse can be strengthened by classical conditioning by pairing a tone with a air puff
44
Q

Name the concept: the increase in synaptic strength that occurs in weak synapses when they are active right around the time when stronger inputs caused the postsynaptic neuron to spike

A

Associative long-term potentiation

45
Q

Describe Hebb’s rule

A
  • Hypothesis by Donald Hebb
  • Kind if overly simplified
  • Says that the cellular basis of learning involves the strengthening of synaptic connections that are active when the postsynaptic neuron fires an action potention
  • BASED ON THR FACT THAT THE CONNECTION EXISTED BEFORE
46
Q

How will a brain slice of the hypocampus affect LTP? (Long-term potentiation)

A
  • its very easy to induce synaptic plasticity
  • To demonstrate associative learning
  • There seems to be an area in the hippocampus where synaptic plasticity is so easy and synapses will strengthen or weaken super fast
  • they pair together top (weak) synapses and bottom (strong) synapses in the hippocampus.
47
Q

What is a dentritic spike?

A
  • it’s the depolarization of all dendrites when an action potential occurs in one dendrite.
  • this causes the chance for any synapse in all dendrites to strengthen
48
Q

Name the 4 types of learning

A
  • Perceptual learning
  • Motor learning
  • Relational learning
  • Stimulus-response learning
49
Q

Name the type of learning:
- Learning to recognize stimuli as distinct entities (ex: language$

A

Perceptual learning

50
Q

Name the type of learning:
- Learning to make skilled, choreographed movements. Procedural learning.

A

Motor learning

51
Q

Name the type of learning:
- Learning relationships among individual stimuli. Stimulus-Stimulus learning. This is what makes us the entire encyclopedia of our knowledge about the world

A

Relational learning

52
Q

Are perceptual learning and motor learning automatic?

A
  • some of these things are automatic, but you actually have to focus on it and put effort. This will make you get better at it very quickly. Ex: riding a bike. If you never try, never put any effort, you could really never learn how to ride a bike. The more you do it, the more you are good at it
53
Q

Name the type of learning:
-Learning to perform a particular behaviour when a particular stimulus is present. Includes classical and instrumental conditioning.

A

Stimulus-response learning

Psyc 211 (9 decks)

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