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Long term potentiation and synaptic plasticity

Learn about synaptic plasticity and long-term potentiation, the physiological mechanism behind learning. Created by Carole Yue.

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  • hopper jumping style avatar for user Jacob Anderson
    If explained correctly, doesn't this fundamentally call into question that the the amplitude (the positive potential) of a neuronal spike does not change, only the frequency of firing alters.

    Maybe this is what Carol meant, but she says "the same pre-synaptic stimulated converts into a greater post synaptic potential".

    Is this an issue of lanuage or actually what happens -- the potential in the post synaptic cell is actually greater after long term potentiation.
    (11 votes)
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    • piceratops ultimate style avatar for user andrewac
      I believe she means that the pre-synaptic stimulus will lead to a greater depolarization in the dendrite/cell body of the post-synpatic neuron. Post-synpatic neurons need to be stimulated by many different pre-synaptic neurons in order to have enough depolarization at the axon hillock to fire an action potential. If the pre-synaptic neuron is able to produce a greater depolarization in the axon, it is more likely that the overall result of all the pre-synaptic neurons' activity on the post-synaptic neuron will be a depolarization at the axon hillock sufficient for action potential. The action potential itself will be the same amplitude.
      (25 votes)
  • leafers ultimate style avatar for user Justin
    Can using some psychoactive drugs increase LTP?
    (5 votes)
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    • mr pants purple style avatar for user Jake
      Taking a stimulant could make you more attentive to learning, and therefore make more connections when exposed to new information, so I would argue yes. Though each drug acts differently and also may impact LTP negatively in some ways.
      (4 votes)
  • blobby green style avatar for user Shrineil Patel
    This is more of a general question; how does LTP work in a individual with an addiction? Does tolerance negate the effect of LTP or are they mutually exclusive?
    (2 votes)
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    • hopper cool style avatar for user SofiyaMarkova
      Long term potentiation is like learning. Learning is more of a habit. Using the same pathway causes it to be more easily accessible and becomes easier to be done by default.
      So it keeps performing what generates that response. In a way the brain learns and so strengthens the pathway that corresponds to the addiction. Study -> do well on a test -> like the feeling of getting a good grade: therefore, will study again. It is a process of learning.
      The brain gets used to doing this, so habits develop. Ex. One was a good student because studied in high school. As they enter into university, their brain is used to the habit of studying, since it learned, so is able to follow through with the activity: maybe before bed they automatically remember to make a plan for the next day.
      Addictions are different:
      “Addiction cannot be controlled and requires professional help for modification”. It is more of a mental disorder where there is an imbalance with brain chemistry.
      (2 votes)
  • leaf green style avatar for user Julia Driscoll
    () how does the pre-synaptic neuron, after repeated stimulation, result in a greater post-synaptic potential if neurons exhibit the ALL or NONE effect?
    (2 votes)
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    • starky seedling style avatar for user Nick
      A few different ways:

      (1) the pre-synaptic neuron may cause release of more neurotransmitters per action potential
      (2) the post-synaptic neuron creates more receptors for the neurotransmitters to bind
      (3) the post-synaptic receptors become more sensitive to the incoming neurotransmitter (number of receptors does not change)
      (1 vote)
  • blobby green style avatar for user karenowusuamends
    So, in long term potentiation, one neuron becomes more sensitive to signals from another specific neuron?
    (1 vote)
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    • blobby green style avatar for user abdelkarimomar14
      Based on what I know, long-term potentiation occurs through:
      1.) The post-synaptic neuron becoming more sensitive to the stimulus from the pre-synaptic neuron (maybe by expressing more receptors to the NT released by the pre-synaptic neuron)

      2.) The pre-synaptic neuron releasing more of the stimulant (NT) into the synaptic cleft, which results in a higher likelihood that the post-synaptic neuron will be depolarized.

      Please feel free to correct me on this!
      (1 vote)

Video transcript

How do you learn? This is a tougher question than it seems. You might know that you learn by studying, for example, but what changes occur in your brain when you read a chapter for the first time or when you test yourself on your knowledge? You probably realize that your brain doesn't just grow new cells to store your memories, otherwise our heads would just get bigger and bigger. What does happen is that connections between neurons strengthen. This is called long-term potentiation, or LTP and it's one example of synaptic plasticity, which is the ability of synapses to change their strength. Let's look at this process in more detail. Neurons communicate using electrochemical signals, that means a combination of electricity and chemicals. When neurons communicate, they actually don't connect to each other directly, there's a junction in between called the synapse. So we have a pre-synaptic neuron, which is a neuron leading up to the synapse, and we have a post-synaptic neuron, which is the neuron immediately following the synapse. When the pre-synaptic neuron is stimulated, it releases neurotransmitters, or special chemicals which then bind to receptors on the post-synaptic neuron, opening channels to allow ions such as sodium and calcium to flow in. All neurons have a surrounding membrane and the interior has a different electrical charge than the exterior of the membrane. This difference in charges is called the neuron's potential. The number of ions that flow into the post-synaptic neuron affect that difference. This is how we measure the strength of the synapse, by how much the post-synaptic neuron's potential changes as a result of pre-synaptic stimulation. With repeated stimulation, the same level of pre-synaptic stimulation converts into <i>greater</i> post-synaptic potential. In other words, after the pre-synaptic neuron gets a lot of practice firing and sending signals to a specific post-synaptic neuron, it gets <i>better</i> at sending those signals, and will get better at opening the channels to allow more ions in. When this happens, we say that the synapse strength is increasing. When this increased strength lasts for a long time, meaning anywhere from a few minutes to many months, it's called long term potentiation. This is thought to be the physiological mechanism by which learning occurs. As synapses are strengthened and they retain that strength, we're able to more easily recall previous experiences.