That’s a good reason why we sometimes feel stuck between impulse and logic.
asserted
we → ’ → impulse
New research from Georgia Tech challenges the popular notion of a primitive “lizard brain” sitting below a newer, rational brain.
asserted
research → challenge → brain
Instead, scientists suggest, it may have been a competition between fundamentally different ways of wiring neural circuits, with limited brain space forcing different systems to compete, which influenced brain evolution.
uncertain
which → suggest → evolution
Published in Science Advances, the study draws on comparisons of biological brains and experiments on artificial neural networks to suggest a new framework for understanding the evolution of intelligence.
asserted
study → publish → intelligence
The old model was devised in the 1950s and perceived the brain in evolutionary layers, with basic bodily functions at the bottom, followed by an emotion-driven reptilian brain and finally the complex neocortex associated with human reasoning.
asserted
model → devise → reasoning
But researchers now say this view is overly simplistic.
asserted
view → say → ?
The neocortex is involved in functions including vision, perception and reasoning.
asserted
neocortex → involve → vision
The so-called limbic system, often loosely described as the “reptilian brain,” is much more complicated.
asserted
system → call → brain
Its components play a role in memory, smell, navigation and emotional regulation and other functions.
asserted
components → play → memory
Rather than looking at the regions as separate structures, the Georgia Tech team examined how those regions change together across species.
asserted
regions → look → species
They discovered that if one part of the limbic system was relatively large, then other parts of the limbic system were likely to be larger as well.
asserted
parts → discover → system
At the same time, the neocortex generally occupied less of the brain.
asserted
neocortex → occupy → brain
That coordinated pattern suggests these regions may function as interconnected systems whose sizes shift together during evolution.
uncertain
sizes → suggest → evolution
This finding raised another question: what could drive this trade-off?
uncertain
what → raise → off
Perhaps the answer lies in the wiring of the brain before birth.
asserted
answer → lie → birth
Two different ways to wire a brain
Neocortical circuits often are arranged as spatial maps.
asserted
circuits → wire → maps
Adjacent parts of the body correspond to parts of the brain, and visual and auditory information can also be organized in terms of spatial relationships.
asserted
information → correspond → relationships
The limbic system goes the other route.
asserted
system → go → route
Its connections are more distributed, like a barcode, with specific patterns of neural activity representing complex information such as smells or memories.
asserted
connections → distribute → smells
To see if these differences were fundamental or just learned through experience, the researchers used artificial neural networks.
asserted
researchers → see → networks
Networks with localized connections performed well on vision, sound and touch tasks.
asserted
Networks → localize → tasks
Distributed wiring, meanwhile, was better suited to smell recognition and memory tasks.
asserted
wiring → distribute → tasks
An evolutionary struggle for brain space
The team then modeled how these two wiring strategies would compete for scarce neural resources.
asserted
strategies → model → resources
The system in an artificial environment that rewarded smell, grew while the simulated neocortex shrank.
asserted
neocortex → reward → smell
When vision became more important, the balance shifted.
asserted
balance → become → ?
The model shows differences seen in real animals.
asserted
model → show → animals
The nine-banded armadillo has a relatively large limbic system, which is heavily reliant on smell.
asserted
which → have → smell
Squirrel monkeys are highly visually dependent and their brains are dominated by the neocortex.
asserted
brains → dominate → neocortex
And in 182 species, the scientists saw evidence that evolution isn’t just adding new layers of intelligence.
asserted
evolution → see → intelligence
Instead, it may be allocating scarce neural real estate to whatever wiring strategy best suits an animal's surroundings.
uncertain
strategy → allocate → surroundings
What this could mean for AI
The finding could have implications beyond understanding the evolution of biology.
uncertain
finding → mean → biology
Contemporary artificial intelligence systems usually rely on large scale training data.
asserted
systems → rely → data
But biological brains start out with a lot of prewired architecture and then combine that built-in structure with experience.
asserted
brains → start → experience
Recreating some of that architecture in artificial neural networks could one day lead to artificial intelligence systems that learn with less data and consume less energy.
uncertain
that → recreate → energy
Thus, the research suggests an alternative view of intelligence, not as a simple hierarchy of ancient and modern brain regions, but as the result of an evolutionary balancing act between different ways of processing information.
uncertain
research → suggest → information
The "lizard brain" is a catchy metaphor, but the truth appears to be far more complicated.
asserted
truth → appear → ?
Evolution didn't just build a smarter brain on top of an older one.
asserted
Evolution → build → one
It may have been all the time negotiating what kind of wiring was worth the space.
uncertain
kind → negotiate → wiring
