The Brain Through a Systems Architect's Eyes

Distributed processing, feedback, prediction and state are often better engineering metaphors than a single CPU because brain activity is massively parallel and…

I approach the brain with an occupational habit: I want to draw boxes and arrows. That habit is useful because architecture forces questions about state, boundaries, interfaces, resources and failure. It is dangerous because natural systems were not designed to respect our diagrams.

The brain is a living network of neurons and glia embedded in a body. Its activity depends on sensory input, internal physiology, past learning, neuromodulation and continuous interaction with muscles and organs.

Where does state live?

Software gives us the expectation that important state should have an owner. Natural systems often distribute state across structure, concentrations, relationships and history. A snapshot can therefore tell us less than the process that produced it.

Where are the interfaces?

Distributed processing, feedback, prediction and state are often better engineering metaphors than a single CPU because brain activity is massively parallel and recurrent.

Engineered interfaces are declarations. Natural boundaries are often material: membranes, tissues, ecological borders, channels, gradients or social conventions. They can leak, adapt and participate in the behavior they constrain.

What is the failure model?

A CPU executes explicit instruction sets on a deliberately designed architecture. Brains grow, metabolize, rewire, learn, recover and degrade through physical changes to the network.

Failure analysis is useful because normal operation hides assumptions. A healthy component can coexist with an unhealthy whole. A local optimization can damage the larger system. Robustness at one level can create fragility at another.

History is part of the architecture

Cajal's neuron doctrine helped reveal individual nerve cells; electrophysiology and imaging later exposed brain dynamics across many scales.

In a designed system, legacy structure may be accidental baggage. In an evolved or historically accumulated system, legacy structure can be the reason the current architecture exists at all. The path is not documentation around the system; sometimes it is part of the system.

The zoom test

A good architectural description should survive zooming. Going down a level should reveal mechanisms capable of implementing the higher-level pattern. Going up should reveal regularities that justify discussing the larger entity in its own vocabulary.

The brain is matter that can build models of other things and, apparently, models of itself.

What does a physical network need to model before a point of view appears?

Reading trail

These links are starting points for the scientific and historical ideas. The systems interpretation, analogies and conclusions here are my own.