Synaptic Plasticity and the Molecular Rules of Change · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Inputs that fire together wire together

Science · The Human Body · ages 19-21
Name ______________________   Date ____________

  1. Which receptor type works as the coincidence detector?

    • The type that needs chemical plus firing together
    • The type that needs neither condition
    • A pump that moves ions all day

  2. An input fires just before its target cell. What happens to that link?

    • It always weakens
    • Nothing ever changes
    • That link strengthens

  3. Lasting strengthening follows correlated firing and weakening follows reversed firing.

    Circle one:   True   False

  4. Both conditions hold and calcium floods in. What does that trigger?

    • A lasting upgrade of the link
    • Instant erasure of the cell
    • A new axon growing out

  5. You record a target spike first and the input just after. What do you predict?

    • It strengthens
    • It weakens
    • It stays exactly the same

  6. You find a strengthened link under the microscope. What changed?

    • Fewer spikes in the sender
    • A wider synaptic gap
    • More receiving spots in the membrane

  7. A classmate says any active input strengthens. Is that right?

    • No, quiet inputs that miss the window get weakened
    • Yes, every active input strengthens
    • Yes, timing never matters

  8. An input keeps arriving just after its target fires, day after day. What happens?

    • Strengthen it
    • Weaken it
    • Leave it unchanged
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Inputs that fire together wire together W1-mt_HldevO4Lzw-s1

  1. The type that needs chemical plus firing together · Only the double condition type lets calcium in, which marks coincidence.
  2. That link strengthens · Input just before the target fires means the input helped, so it earns strengthening.
  3. True · Correlated trains build lasting strengthening, reversed trains build lasting weakening.
  4. A lasting upgrade of the link · The calcium pulse signals that this input helped, so the link earns an upgrade.
  5. It weakens · Target before input means the input did not help cause the firing.
  6. More receiving spots in the membrane · Extra receiving spots make the same puff of chemical produce a bigger current.
  7. No, quiet inputs that miss the window get weakened · Only a real spike opens the window, and only inputs inside it earn the upgrade.
  8. Weaken it · Repeated reversed order is the classic recipe for lasting weakening.
Worksheet · LightMySky