• A single postsynaptic neuron can be like the cool kid in school: many (hundreds or thousands!) presynaptic neurons want to connect with it, especially in the brain.

🍔 Real-world example: Imagine a restaurant (our postsynaptic neuron) getting food deliveries (messages) from multiple delivery drivers (the presynaptic neurons). They all want to deliver their food to that one restaurant!

• One splash (excitatory neurotransmitter) from a single presynaptic neuron isn’t enough to make a big wave (action potential).
• To get a wave, you either need:
  • The same kid (presynaptic neuron) to keep splashing repeatedly.
  • Or a bunch of kids (several presynaptic neurons) to splash all at once.

🌊 Real-world example: To create a big wave in a pool, you either need one person making repeated jumps, or multiple people jumping in at once.

• When multiple splashes combine to make a wave, it’s called summation.
• But it’s not just about excitatory splashes. Some neurotransmitters are party-poopers (inhibitory neurotransmitters) and stop the wave from forming.
• It's a tug-of-war between excitatory and inhibitory neurotransmitters. For an action potential to happen, the excitatory side needs to pull much harder!

🎈 Real-world example: Think of a balloon race. Excitatory neurotransmitters are trying to inflate the balloon (reach threshold potential) while inhibitory neurotransmitters are letting air out. The balloon will only fly if it's more inflated than deflated.