- The correct answer is Hebbian plasticity. This neurophysiological principle is often summarized by the phrase "cells that fire together, wire together."
- It describes the process where simultaneous activation of pre- and postsynaptic neurons strengthens the synaptic connection between them.
- When neurons are consistently activated at the same time, the efficiency of synaptic transmission is enhanced, leading to strengthening of the synapse.

- In contrast, homeostatic plasticity helps maintain overall neural activity within a functional range by scaling synaptic strengths up or down, but it is not specifically about simultaneous activation.

- Long-term potentiation (LTP) refers to a long-lasting enhancement in signal transmission between two neurons that results from their synchronous stimulation. While closely related and often considered a cellular mechanism underlying Hebbian plasticity, LTP is a specific phenomenon observed experimentally.

- Synaptic pruning is the process of eliminating weaker synaptic connections to refine neural circuits, which is different from the strengthening described in this question.

Thus, the principle describing the strengthening of synapses due to simultaneous neuronal activation is best captured by Hebbian plasticity.

Reference: Principles of Neural Science, 5th Edition, Chapter 19, Page 453