Physical Memory Coding: Storing Foraging History in Tube Diameters

Your blob does not store experience in a brain. It stores experience in architecture.

When routes carry sustained useful flow, tube diameters increase. When routes underperform, tubes shrink and disappear. The network becomes a physical log of what worked.

Memory as geometry

This is called morphological memory (memory represented by persistent structural change).

In Physarum, diameter is a key state variable. Wider channels tend to maintain higher conductance and attract future flow.

The feedback loop

1. Resource detection boosts local transport demand.
2. Flow increases in selected routes.
3. High-use routes reinforce.
4. Reinforcement makes those routes even more favorable.

At the same time, weak routes are demoted. Memory is produced by differential maintenance.

Why this changes future behavior

When the organism faces a new choice, existing high-conductance geometry biases traffic allocation. It does not start from a blank slate each cycle.

That is history-dependent behavior implemented without neurons.

Practical implications for experiments

If you reset geometry aggressively between trials, you erase a major memory channel. If you keep geometry intact, you are measuring both current cues and historical bias.

Both can be valid, but do not mix them without noting it in protocol.

Engineering analogy

The system resembles history-sensitive conductance components in electronics. Route resistance depends on prior flow exposure.

This is one reason Physarum keeps informing decentralized adaptive-network design.

Related reading: External Spatial Memory, SMT Analysis, and Knowledge Transfer.