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.
Nature, however, already seems to have made axons nearly as thin as they can be: any thinner, and the random opening of the channels would make axons too noisy, meaning that they would deliver too many signals when the neuron was not supposed to fire.
The problem is that ion channels are not precisely controllable. Instead, they open and close at random many times a second. Electrical signals only change the likelihood that they will open. In a typical axon the random opening of an ion channel does not have serious consequences, because the channel closes again before letting in too many ions (first animation).
If evolution made axons much thinner, however, the opening of a single ion channel would often create a spurious signal which then would travel down the axon. Too much of this noise would make the neuron unreliable.
— Davide Castelvecchi
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Add CommentI remember...perched in a Mesquite tree in my grandmother's back yard, leaning out more and more, intending to jump. Balanced precariously and knowing I was going to jump down from there, but afraid nonetheless, I waited. At last I jumped! But why at that precise time? A random axon firing upset the delicate balance I had put myself in. And now I know.
Reply | Report Abuse | Link to thisGlenk, You have a good theory but a more plausible one is that nature reminded you that your bladder was full and it was time to pee.
Reply | Report Abuse | Link to this'smaller is better' only works for myelinated (electrically insulated) axons. an adaptation of invertebrates is to increase the diameter of axons, effectively lowering the resistance of current flow within the axon, relative to the resistance across the membrane. cable theory explains this well: http://en.wikipedia.org/wiki/Cable_theory
Reply | Report Abuse | Link to thisit's nonlocal anyway.
Reply | Report Abuse | Link to thisHow can we compare brain with machine?We are human being there are limit for our efficiency,With some work our brain tried want some rest.Computer have no soul is made by iron as you put more strong chip in it show more efficiency.How can you put more stronger energy in brain?Another question some scientist are making so strong computer who can take brain`s place and human brain will be obsoleted.This is a nonsense statement.Can computer have thinking faculty ,creative mind? After all computer is machine what we feed them,instruct them it will give response to that contrary brain can create absolutely new idea, new devises computer have that power?Computer have more efficiency in his limit.
Reply | Report Abuse | Link to thisMaybe thinner axons tend to trigger too much accidental firing that requires additional corrective activities, which in turn rendering the whole idea of 'thinner axons' fruitless.
Reply | Report Abuse | Link to thisIn dealing with neural complexity and network functionality, I have invented a new thinking model called- Computational Spherical Modeling (CSM), which seems to provide a transformative new approach to study brains.
People can change the world simply by using their own energy said a Russian scientist. He asserted that thinking in a certain direction can have a positive or negative effect on the surrounding environment.
Reply | Report Abuse | Link to thishttp://goo.gl/btYUD
AHA! I like this 'explanation' for much of my own 'stupid', 'pointless' behavior in all those 77 years of an interesting but very frustrating 'LIFE'. It's why I am NOT rich OR famous and may DIE before my oldest Grandfather did (105). My younger croked at(69). So, WHAT does 'LUV' or'GOD' have to DO with it all? HOORAY for my 'FAT' neurons! Is this why I'm a 'Fathead?
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