Plasticity & Stability
Practice stabilises connections and speeds familiar routes; less‑practised circuits stay more plastic and repurposable. It's a trade off---the more you practice something, the more infrastucture the brain will build to support it, which makes it harder to change later.
Neural connections change with use. There is an old adage, "neurons that fire together, wire together", and it's true that co‑activation of nerve cells strengthens links between them and sharpens how in-sync they are. Repetition consolidates the connections between so the circuit runs faster and more reliably. This means that a neural pathway---a mapping from input to output in the brain---becomes the path of least resistance the more often you run it.
This comes with a trade‑off though. A neural route that has been consolidated is, at least in the short term, less easy to change. The less practiced the circuit, the more plastic it's likely to be, and the easier it'll be to repurpose or alter.
The reason for this isn't just because the connections between neurons are stronger, but also because the brain builds additional infrastructure around the circuits it uses a lot. This infrastructure protects, nourishes, repairs, and improves the performance of the circuit, but obviously makes it more difficult to re‑wire---you need to change the wiring and the infrastructure supporting the wiring!
It’s a useful way to think about differences across development: adolescents famously have much less of this kind of support---this is what brain scientists mean when they say 'teenage brains are undeveloped'. As such, they tend to be more behaviourally flexible. Adults, on the other hand, tend to be more efficient, but equally, more inertial.
Now, because neural circuits are reused, consolidating one will influence others---strengthening those that share more segments and weakening those who might have relied on infrastructure that you're re-purposing. New routes will do best where infrastucture already exists to support it, and older and more established routes will be hard to change not just because of all the infrastructure it uses, but because of all the similar routes that keep that infrastructure in place.
How can you think with this?
These heuristics help you apply this neural system:
Ways to think with this
Practical ways to use this neural mechanism in understanding behaviour
WIP: Repetition makes the default sticky
Co-activation strengthens the connections between neurons, so the more often an input produces an output, the more likely that pathway is to run next time. This is useful for building skill and speed, but it also means the pathway becomes harder to change---you're not just fighting the connection strength, you're fighting all the infrastructure the brain has built to support it.
So what can you do? If you're trying to establish a new input-output mapping, expect to practise it many times before it becomes automatic. And if you're trying to change an old one, expect resistance. The old pathway isn't just a habit; it's a piece of infrastructure. Add the new route first, get it running reliably, then taper the old one. Don't try to delete and replace simultaneously.
WIP: Cheap action beats expensive revision
A consolidated pathway runs fast and costs little metabolically, which means acting on it is cheaper than stopping to revise it. This is why you can 'know better' and still do the thing---the system is optimised to minimise effort, and running the trained route is almost always cheaper than overriding it in the moment. The brain is lazy in a very literal sense: it defaults to the path of least resistance.
So what can you do? Don't rely on willpower in the moment. It's not that you lack discipline; it's that you're asking the system to take the expensive option when a cheap one is available. Instead, retrain the pathway in advance so the cheap option is the one you want. Make the desired behaviour automatic, and let the laziness work for you instead of against you.
WIP: Flexibility costs efficiency
The more you consolidate a pathway, the faster and more reliable it becomes, but also the less flexible. This is the trade-off: you can have speed and stability, or you can have plasticity and adaptability, but you can't have both in the same circuit at the same time. Adolescents are more flexible because their pathways haven't been stabilised yet; adults are more efficient because theirs have.
So what can you do? Match your expectations to the trade-off. If you need flexibility, maintain variation and avoid over-consolidating any single route. If you need reliability, practise until the pathway is stable. And if you're an adult trying to change a long-standing pattern, recognise that you're optimised for efficiency now, not exploration. Give yourself more time and margin than you think you need.
WIP: Consolidation extends beyond the target
When you consolidate a pathway, you're not just strengthening that one route---you're also strengthening the infrastructure that supports it, and that infrastructure is often shared with other pathways. This means practising one thing can inadvertently stabilise others that use the same segments, and changing one thing can destabilise its neighbours. The brain is economical; it reuses what it has.
So what can you do? Expect that changing one behaviour will affect others. Sometimes that's helpful---learning one skill improves related skills. Sometimes it's not---changing one habit destabilises others that were relying on the same infrastructure. Plan for spillover, and be ready to adjust other patterns that share resources with the one you're targeting.
Sources
- analects/repressed-memories.md
- analects/details-of-trauma.md
- analects/frontal-lobe-development.md
- analects/what-are-neurons.md