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To further emphasize that having neural material focused on the appropriate functions is more important vs how much you have, here is a story about a guy whose

To further emphasize that having neural material focused on the appropriate functions is more important vs how much you have, here is a story about a guy whose brain is mostly hollow and filled with fluid, it probably did cause his IQ to be 75 and causes him weakness in his legs, but otherwise he lives a normal adult life more or less. https://www.newscientist.com/article/dn12301-man-with-tiny-brain-shocks-doctors/ https://www.newscientist.com/article/dn12301-man-with-tiny-b...

acchow 5y ago
Doesn't this demonstrate the opposite of what you were claiming?
- lacksconfidence 5y ago
  I feel like the quotes agree with parent: > “If something happens very slowly over quite some time, maybe over decades, the different parts of the brain take up functions that would normally be done by the part that is pushed to the side,” adds Muenke, who was not involved in the case.
- Ajedi32 5y ago
  Did you see the scans? The dude's head is practically empty (brain 55-75% smaller than normal) and nobody even noticed until he was 44 years old and got an MRI.
- divbzero 5y ago
  I think it’s that a priori you would expect a hollow brain to have a far more drastic effect and not allow for a mostly normal adult life.
  - pishpash 5y ago
    Why would you expect that, when a tiny insect can do pretty intelligent things? What "unexpected" things humans can do are probably all in the >75 IQ range.
gwern 5y ago
Volume != neurons. In any case, 75 is awful and is usually considered borderline retarded. (If you're tempted to respond with other cases of higher IQ, note that they are often retracted or unconfirmed and likely fraudulent in some way; see https://www.gwern.net/Hydrocephalus https://www.gwern.net/Hydrocephalus .)
- willmw101 5y ago
  >Volume != neurons Exactly. Most of the newer research on this topic suggests that it's neural connection complexity, and specifically frontal lobe volume, rather than overall brain size that determines intelligence or brain power. https://neuroscience.stanford.edu/news/ask-neuroscientist-does-bigger-brain-make-you-smarter https://neuroscience.stanford.edu/news/ask-neuroscientist-do... >Luckily, there is much more to a brain when you look at it under a microscope, and most neuroscientists now believe that the complexity of cellular and molecular organization of neural connections, or synapses, is what truly determines a brain’s computational capacity. This view is supported by findings that intelligence is more correlated with frontal lobe volume and volume of gray matter, which is dense in neural cell bodies and synapses, than sheer brain size. Other research comparing proteins at synapses between different species suggests that what makes up synapses at the molecular level has had a huge impact on intelligence throughout evolutionary history. So, although having a big brain is somewhat predictive of having big smarts, intelligence probably depends much more on how efficiently different parts of your brain communicate with each other.
- mattkrause 5y ago
  As a counterpoint, rats without a cortex can do...basically everything normal rats can do--except trim their toenails. The classic reference for this is Whitslaw's 1990 chapter "The decorticate rat". This thread has links to a copy, plus a bunch of related studies in humans and animals. https://twitter.com/markdhumphries/status/1071052762765541376 https://twitter.com/markdhumphries/status/107105276276554137...
  - heavenlyblue 5y ago
    Have you read the PDF given? The whole nail part is basically a single sentence in the paper. For example, decorticate rats are unable to escape narrow alleyways because they can not turn around due to their tonsils touching the walls and them being unable to ignore that feeling. Another example is that they take a few seconds vs (!) 5 minutes to groom themselves on average.

acchow 5y ago

Doesn't this demonstrate the opposite of what you were claiming?

lacksconfidence 5y ago
I feel like the quotes agree with parent: > “If something happens very slowly over quite some time, maybe over decades, the different parts of the brain take up functions that would normally be done by the part that is pushed to the side,” adds Muenke, who was not involved in the case.
Ajedi32 5y ago
Did you see the scans? The dude's head is practically empty (brain 55-75% smaller than normal) and nobody even noticed until he was 44 years old and got an MRI.
divbzero 5y ago
I think it’s that a priori you would expect a hollow brain to have a far more drastic effect and not allow for a mostly normal adult life.
- pishpash 5y ago
  Why would you expect that, when a tiny insect can do pretty intelligent things? What "unexpected" things humans can do are probably all in the >75 IQ range.

gwern 5y ago

Volume != neurons. In any case, 75 is awful and is usually considered borderline retarded. (If you're tempted to respond with other cases of higher IQ, note that they are often retracted or unconfirmed and likely fraudulent in some way; see https://www.gwern.net/Hydrocephalus https://www.gwern.net/Hydrocephalus .)

willmw101 5y ago
>Volume != neurons Exactly. Most of the newer research on this topic suggests that it's neural connection complexity, and specifically frontal lobe volume, rather than overall brain size that determines intelligence or brain power. https://neuroscience.stanford.edu/news/ask-neuroscientist-does-bigger-brain-make-you-smarter https://neuroscience.stanford.edu/news/ask-neuroscientist-do... >Luckily, there is much more to a brain when you look at it under a microscope, and most neuroscientists now believe that the complexity of cellular and molecular organization of neural connections, or synapses, is what truly determines a brain’s computational capacity. This view is supported by findings that intelligence is more correlated with frontal lobe volume and volume of gray matter, which is dense in neural cell bodies and synapses, than sheer brain size. Other research comparing proteins at synapses between different species suggests that what makes up synapses at the molecular level has had a huge impact on intelligence throughout evolutionary history. So, although having a big brain is somewhat predictive of having big smarts, intelligence probably depends much more on how efficiently different parts of your brain communicate with each other.
mattkrause 5y ago
As a counterpoint, rats without a cortex can do...basically everything normal rats can do--except trim their toenails. The classic reference for this is Whitslaw's 1990 chapter "The decorticate rat". This thread has links to a copy, plus a bunch of related studies in humans and animals. https://twitter.com/markdhumphries/status/1071052762765541376 https://twitter.com/markdhumphries/status/107105276276554137...
- heavenlyblue 5y ago
  Have you read the PDF given? The whole nail part is basically a single sentence in the paper. For example, decorticate rats are unable to escape narrow alleyways because they can not turn around due to their tonsils touching the walls and them being unable to ignore that feeling. Another example is that they take a few seconds vs (!) 5 minutes to groom themselves on average.