Perspectives
The Nervous System Through a Systems Architect's Eyes
Networking language helps with topology, latency, propagation, synchronization and routing-like questions. It is especially useful for asking how local events influence a large connected…
I approach the nervous system 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.
Neurons maintain electrochemical gradients, generate action potentials and communicate through electrical and chemical synapses. Timing, connectivity, modulation, plasticity and circuit state all shape what a signal does.
Where does state live?
Neurons maintain electrochemical gradients, generate action potentials and communicate through electrical and chemical synapses. Timing, connectivity, modulation, plasticity and circuit state all shape what a signal does.
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?
Networking language helps with topology, latency, propagation, synchronization and routing-like questions. It is especially useful for asking how local events influence a large connected system.
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 neural spike is not an Ethernet packet with a universal payload. Its significance depends on which neuron fired, when, and how the receiving network is currently configured.
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
Studies of biological electricity led from nerves and action potentials to circuit-level and computational neuroscience.
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 nervous system blurs communication and computation because transmitting a signal can also modify the network that gives the signal meaning.
When does a network stop merely transmitting information and begin constructing a model of the world?
Reading trail
These links are starting points for the scientific and historical ideas. The systems interpretation, analogies and conclusions here are my own.