Synaptic Plasticity
The ability of synapses (connections between neurons) to strengthen or weaken over time in response to increases or decreases in their activity.
"Neurons that fire together wire together." That phrase, coined by Donald Hebb in 1949, captures the essence of synaptic plasticity. When two neurons fire simultaneously and repeatedly, the connection between them strengthens (long-term potentiation, or LTP). When a connection goes unused, it weakens (long-term depression, or LTD). This is the cellular mechanism underlying every skill you've ever learned and every fact you've ever memorized. It's also the biological basis of "use it or lose it" — skills you don't practice fade because the underlying synaptic connections weaken without regular activation.
Frequently Asked Questions
What is the difference between LTP and LTD?
Long-term potentiation (LTP) strengthens synaptic connections — it's the "wire together" part. Long-term depression (LTD) weakens them — it's the pruning mechanism that removes unused connections. Both are essential: LTP encodes new learning, while LTD clears out noise and sharpens relevant pathways. Together they sculpt your brain's circuitry based on experience.
Why does "use it or lose it" apply to cognitive skills?
Synaptic connections require regular activation to maintain their strength. When you stop practicing a skill, the underlying neural pathways weaken through LTD — the synaptic connections literally diminish. This is why consistent cognitive practice matters more than occasional intense sessions. Regular use keeps pathways strong.