2-Minute Neuroscience: Synaptic Transmission

Scientific concepts / nature phenomena presented

• Neuronal communication via synapses

  • Neurons communicate at specialized structures called synapses.
  • A synapse is not a direct connection; it is separated by a microscopic gap called the synaptic cleft (described as < 40 nm; human hair ~75,000 nm).

• Presynaptic vs. postsynaptic neurons

  • Presynaptic neuron: the cell that initiates the signal.
  • Postsynaptic neuron: the cell that receives the signal.

• Chemical synaptic transmission

  • The presynaptic neuron releases neurotransmitters.
  • Neurotransmitters are stored in small membrane-bound sacs called vesicles.
  • Each vesicle can contain thousands of neurotransmitter molecules.

• Triggering release by electrical activity

  • An action potential excites the presynaptic neuron.
  • Excitation causes vesicle fusion with the presynaptic membrane and release of neurotransmitters into the synaptic cleft.

• Postsynaptic receptor binding and response

  • Neurotransmitters bind to receptors on the postsynaptic membrane.
  • This binding can:
    • Increase the likelihood the postsynaptic neuron will fire an action potential, or
    • Decrease the likelihood (i.e., inhibit firing).

• Termination of synaptic signaling

  • Neurotransmitter clearance mechanisms:
    • Diffusion: neurotransmitters drift away from the cleft.
    • Reuptake: neurotransmitters are taken back into the presynaptic neuron, where they can be recycled and reused.
    • Enzymatic breakdown: enzymes degrade neurotransmitters in the synaptic cleft, and the resulting parts are returned to the presynaptic neuron to rebuild neurotransmitter.

Methodology / process outline (step-by-step)

1. Action potential arrives at the presynaptic neuron
2. Vesicle fusion with presynaptic membrane
3. Neurotransmitter release into the synaptic cleft
4. Neurotransmitter binding to postsynaptic receptors
5. Postsynaptic effect:
   • increased or decreased probability of postsynaptic action potential
6. Neurotransmitter removal from the cleft by:
   • diffusion
   • reuptake
   • enzymatic degradation, followed by recycling of components

Researchers / sources featured

• No specific researchers or external sources are named in the provided subtitles.