Size vs. Connectivity

Does brain size matter when it comes to function? Are larger brains correlated with better function? From what I got from the reading, it seems like, in many cases, it isn’t necessarily the overall size of the brain, but rather, the sizes of different specified regions that can be correlated with enhanced abilities (like the example of Einstein’s abnormally large inferior parietal lobe and enhanced visual/mathematical abilities).

However, Seung’s information on autism contradicts the idea that larger equals better. He points out that individuals with autism tend to have larger heads – in particular, they have larger frontal lobes. Interestingly, the frontal lobe happens to be where many social and linguistic behaviors are located (pg. 19) – and these are two of the biggest areas of difficult for most people with autism. I wanted to see what else Seung/Connectome had to say about autism; I found a section in which he states that too many connections might be made within the frontal lobe, but that not enough connections are made between the frontal lobe and other parts of the brain (pg. 112). The last part of that especially makes sense with his “brain as a factory” analogy, and how “adding more workers could actually reduce output by disrupting the workflow” (pg. 34). Thus, autism seems to be a good example of “performance (depending) less of the number of neurons and more on how they are organized” (pg. 34).

(Interestingly, some suspect that Einstein may have been on the autism spectrum – but that’s a whole different topic.)

The results of hemispherectomies are also convincing evidence (to me) that size is not necessarily an accurate measure of ability and function. It is also very convincing evidence of remapping, and even of how children’s brains are more plastic than adults’. I was wondering, does that mean that children’s brains are not as lateralized as adults (or, at least, not as specialized)? When I looked it up, I found that most studies (including this one) said that younger children actually have more lateralized brains than adults (at least, in terms of language). However, this study does suggest that, when it comes to language anyways, children’s brains are less rigidly specialized than adults.

So, this may be an obvious point, but to me, it seems like connectivity is much more important and more useful than size when talking about the function of the brain.

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2 Comments (+add yours?)

  1. Melissa
    Feb 18, 2013 @ 14:18:42

    Great entry, Eliza, seems very pro-connectome. Do you find yourself also hesitating to embrace it as the source of who you are?

    Reply

  2. Czarina Evangelista
    Feb 20, 2013 @ 23:21:15

    I was very interested in the part that mentioned autism too! Many autistic people are very intelligent (and I believe I learned in Intro to Psych that all, except for one, savants are autistic), which supports that idea that brain size is linked with intelligence. It is really difficult to identify something that can accurately measure intelligence since the entire brain is involved in brain function.

    Reply

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