Faster, Smaller, Better: Does Physics Put an Upper Limit on Brain Efficiency?

From   Scientific American Magazine

Just as shrinking transistors makes computers more powerful, brains with smaller components could in principle pack in more power and become faster. The human neuron, however—and in particular, its long “tail,” called an axon—may already be at (or close to) their physical limit.

Axons are the nervous system’s telegraph wires, enabling neurons to form networks. When a neuron fires, it sends an electrical signal down its axon, which then stimulates other neurons. The signal travels down the axon by opening ion channels embedded in the cellular membrane, letting ions pass through. When enough ions cross a channel, they change the voltage across the membrane, which in turn causes the nearby channels to open, propagating the signal in a domino effect.

In principle, our brains could evolve to have thinner axons, which would save space so that more neurons and more axons could pack in. Thinner axons would also consume less energy.

 

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